api rp 0555 process analyzers (2001)

Process Analyzers

API RECOMMENDED PRACTICE 555SECOND EDITION, NOVEMBER 2001ANSI/API RP 555-2001

Process Analyzers

Downstream Segment

API RECOMMENDED PRACTICE 555SECOND EDITION, NOVEMBER 2001ANSI/API RP 555-2001

SPECIAL NOTES

API publications necessarily address problems of a general nature. With respect to partic-ular circumstances, local, state, and federal laws and regulations should be reviewed.

API is not undertaking to meet the duties of employers, manufacturers, or suppliers towarn and properly train and equip their employees, and others exposed, concerning healthand safety risks and precautions, nor undertaking their obligations under local, state, or fed-eral laws.

Information concerning safety and health risks and proper precautions with respect to par-ticular materials and conditions should be obtained from the employer, the manufacturer orsupplier of that material, or the material safety data sheet.

Nothing contained in any API publication is to be construed as granting any right, byimplication or otherwise, for the manufacture, sale, or use of any method, apparatus, or prod-uct covered by letters patent. Neither should anything contained in the publication be con-strued as insuring anyone against liability for infringement of letters patent.

Generally, API standards are reviewed and revised, reaffirmed, or withdrawn at least everyfive years. Sometimes a one-time extension of up to two years will be added to this reviewcycle. This publication will no longer be in effect five years after its publication date as anoperative API standard or, where an extension has been granted, upon republication. Statusof the publication can be ascertained from the API Standards Department [telephone (202)682-8000]. A catalog of API publications and materials is published annually and updatedquarterly by API, 1220 L Street, N.W., Washington, D.C. 20005.

This document was produced under API standardization procedures that ensure appropri-ate notification and participation in the developmental process and is designated as an APIstandard. Questions concerning the interpretation of the content of this standard or com-ments and questions concerning the procedures under which this standard was developedshould be directed in writing to the general manager of the Standards Department, AmericanPetroleum Institute, 1220 L Street, N.W., Washington, D.C. 20005. Requests for permissionto reproduce or translate all or any part of the material published herein should also beaddressed to the general manager.

API standards are published to facilitate the broad availability of proven, sound engineer-ing and operating practices. These standards are not intended to obviate the need for apply-ing sound engineering judgment regarding when and where these standards should beutilized. The formulation and publication of API standards is not intended in any way toinhibit anyone from using any other practices.

Any manufacturer marking equipment or materials in conformance with the markingrequirements of an API standard is solely responsible for complying with all the applicablerequirements of that standard. API does not represent, warrant, or guarantee that such prod-ucts do in fact conform to the applicable API standard.

All rights reserved. No part of this work may be reproduced, stored in a retrieval system, or transmitted by any means, electronic, mechanical, photocopying, recording, or otherwise,

without prior written permission from the publisher. Contact the Publisher, API Publishing Services, 1220 L Street, N.W., Washington, D.C. 20005.

Copyright 2001 American Petroleum Institute

FOREWORD

API publications may be used by anyone desiring to do so. Every effort has been made bythe Institute to assure the accuracy and reliability of the data contained in them; however, theInstitute makes no representation, warranty, or guarantee in connection with this publicationand hereby expressly disclaims any liability or responsibility for loss or damage resultingfrom its use or for the violation of any federal, state, or municipal regulation with which thispublication may conflict.

Suggested revisions are invited and should be submitted to the Manager of Standardizationof the Downstream Segment, American Petroleum Institute, 1220 L Street, N.W., Washing-ton, D.C. 20005.

iii

CONTENTS

Page

Section A Process Analyzer Considerations

. . . . . . . . . . . . . . . . . . . 1

1 ANALYZER SELECTION DESIGN REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . 11.1 Economic Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2 Environmental and Safety Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.3 Application Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

2 SYSTEM DATA MANAGEMENT REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . 22.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22.2 Analog Transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22.3 Digital Transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22.4 Highway Link . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

3 ANALYZER SYSTEM CALIBRATION AND VALIDATION . . . . . . . . . . . . . . . . . 33.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33.2 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33.3 Validation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

4 SAMPLE CONDITIONING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64.2 Functions of a Sample System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64.3 Design Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

5 PREPACKAGED SYSTEMS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215.2 Advantages of Pre-packaged Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225.3 Total Systems Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

6 MAINTENANCE, TRAINING, INSTALLATION, INSPECTION, TESTING, AND STARTUP REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226.1 Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226.2 Training . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256.3 Installation and Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 276.4 Inspection and Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316.5 Commissioning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

7 SAFETY REQUIREMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 387.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 387.2 Samples Lines and Sample System Components . . . . . . . . . . . . . . . . . . . . . . . . 387.3 Electrical Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 387.4 Personal Safety. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 387.5 Maintenance Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

APPENDIX A REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Section B Safety and Environmental Considerations

. . . . . . . . 41

8 AREA SAFETY MONITORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 418.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

v

2 Area Monitoring for Toxic Gases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 428.3 Area Monitoring for Combustible Gas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 468.4 Area Monitoring for Fire and Smoke . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 478.5 Area Monitoring Sampling Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 518.6 Calibration, Startup, and Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

9 CONTINUOUS EMISSION MONITORING SYSTEMS . . . . . . . . . . . . . . . . . . . . . 549.1 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 549.2 Regulations and Monitoring Requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 549.3 Measurement Techniques Utilized in CEM Systems . . . . . . . . . . . . . . . . . . . . . 579.4 In-situ Analyzers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 589.5 Types of CEMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 589.6 Special Considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 599.7 Safety of CEM Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 599.8 Calibration of CEM Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 609.9 Maintenance of CEM Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

10 WASTEWATER AND WATER TREATMENT ANALYZERS. . . . . . . . . . . . . . . . 6010.1 Total Carbon (TC) and Total Organic Carbon (TOC). . . . . . . . . . . . . . . . . . . . . 6010.2 Total Oxygen Demand Wastewater Analyzers . . . . . . . . . . . . . . . . . . . . . . . . . . 6210.3 Turbidity Analyzers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6310.4 Residual Chlorine Analyzers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6610.5 Hydrocarbons-in-water Analyzers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6910.6 pH Measurements for Wastewater Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7010.7 Dissolved Oxygen in Wastewater Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7110.8 Water Treatment Analyzers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

APPENDIX B REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

Section C Spectroscopic Chemical Composition Analyzers

. 75

11 INFRARED SPECTROSCOPY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7511.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7511.2 Infrared Detectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7511.3 Infrared Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7711.4 Typical Infrared Application Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7811.5 Sampling Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

12 ULTRAVIOLET (UV) SPECTROSCOPY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7812.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7812.2 Measurement Principles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7912.3 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7912.4 Sampling Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7912.5 Installation, Safety, Startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

13 MASS SPECTROSCOPY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7913.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7913.2 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8113.3 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8213.4 Analyzer Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8213.5 Sampling Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8213.6 Safety Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

vi

7 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8213.8 Startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

14 X-RAY ABSORPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8214.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8214.2 Safety Concerns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8314.3 X-ray Absorption Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8314.4 Analyzer Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8314.5 Sampling Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8414.6 Calibration and Startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

15 ION MOBILITY SPECTROSCOPY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8415.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8415.2 Safety Concerns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8515.3 IMS Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8515.4 Analyzer Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8515.5 Sampling Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8515.6 Calibration and Startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

16 NUCLEAR MAGNETIC RESONANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8616.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8616.2 Typical NMR Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8916.3 Sampling Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

APPENDIX C REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

Section D Non-spectroscopic Chemical Composition Analyzers

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

17 GAS CHROMATOGRAPHS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9117.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9117.2 Utilization in Refineries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9217.3 Typical Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9217.4 Application Variables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9817.5 Simplified Chromatograph Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9917.6 Components of the Process Chromatograph. . . . . . . . . . . . . . . . . . . . . . . . . . . . 9917.7 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10917.8 Installation and Inspection of New Analyzer Installations . . . . . . . . . . . . . . . 11017.9 Initial Startup Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

18 MOISTURE ANALYZERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11218.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11218.2 Types of Moisture Analyzers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11218.3 Sampling Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11818.4 Calibration and Startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118

19 OXYGEN ANALYZERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12119.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12119.2 Types of Oxygen Analyzers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12219.3 Sampling Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12719.4 Safety Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128

vii

5 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12819.6 Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129

20 SULFUR ANALYZERS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12920.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12920.2 Measurement Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12920.3 Application Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13020.4 Analyzer Types and Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13020.5 Sample Preparation System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13620.6 Calibration and Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137

APPENDIX D REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139

Section E Physical Property Analyzers

. . . . . . . . . . . . . . . . . . . . . . . 141

21 POUR POINT ANALYZERS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14521.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14521.2 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14521.3 Principles of Pour Point Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14521.4 Operating Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14621.5 Sampling Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14721.6 Installation and Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147

22 CLOUD POINT AND FREEZE POINT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14822.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14822.2 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14822.3 Cloud Point General. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14822.4 Safety Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15122.5 Analyzer Location and Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15122.6 Utility Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15222.7 Sampling Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15222.8 Checking and Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15222.9 Typical Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153

23 DISTILLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15323.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15323.2 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15323.3 Types of Boiling Point Analyzers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15323.4 Typical Boiling Point Analyzer Specifications . . . . . . . . . . . . . . . . . . . . . . . . . 15823.5 Sampling Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15823.6 Installation and Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15823.7 Sample Material Problems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15823.8 Effluent Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159

24 FLASH POINT ANALYZERS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15924.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15924.2 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15924.3 Methods of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15924.4 Sampling Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16124.5 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16124.6 Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161

viii

VAPOR PRESSURE ANALYZERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16125.1 General. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16125.2 Applications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16225.3 Types of Reid Vapor Analyzers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16225.4 Kinetic Vapor Pressure Analyzers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16225.5 Safety Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16525.6 Analyzer Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16525.7 Typical Reid Vapor Pressure Analyzer Specifications . . . . . . . . . . . . . . . . . . 16525.8 Typical Kinetic Vapor Pressure Analyzer Specifications . . . . . . . . . . . . . . . . 16625.9 Sampling Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16625.10 Startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16625.11 Shutdown Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166

26 OCTANE ANALYZERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16626.1 General. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16626.2 Correlative Combustion Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16726.3 Analytical TypeNIR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168

27 PROCESS STREAM VISCOMETERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17627.1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17627.2 Basic Principles of Viscosity Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . 17627.3 Types of Process Viscometers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17727.4 Temperature Compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17827.5 Safety Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17827.6 Location and Housing Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17927.7 Sampling Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17927.8 Calibration Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18427.9 Readout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18527.10 Startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185

28 DENSITOMETERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18528.1 General. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18528.2 Density and Specific Gravity Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18528.3 Liquid DensitometersBasic Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18528.4 Gas DensitometersBasic Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19428.5 Compensation for Factors Affecting Accuracy. . . . . . . . . . . . . . . . . . . . . . . . 19928.6 Safety Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19928.7 Installation Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19928.8 Sampling Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20028.9 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20128.10 Readout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20128.11 Startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202

29 COLOR ANALYZERS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20229.1 General. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20229.2 Applications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20229.3 Color Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20329.4 Sampling Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20329.5 Installation and Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204

APPENDIX E REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204

ix

Page

Section F Chemical Property Analyzers

. . . . . . . . . . . . . . . . . . . . . . 205

30 pH MEASUREMENT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20530.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20530.2 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20530.3 Typical pH Application Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20630.4 Electrode Measuring System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20730.5 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21030.6 Weather Protection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21530.7 Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21530.8 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21530.9 Startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216

31 OXIDATION-REDUCTION POTENTIAL (ORP) MEASUREMENT. . . . . . . . . . 21631.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21631.2 Typical ORP Application Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21631.3 Factors Affecting Oxidation/Reduction Measurements . . . . . . . . . . . . . . . . . . 21631.4 Oxidation-reduction Voltages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21831.5 Electrode Measuring System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21831.6 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21831.7 Standardization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21831.8 Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219

32 ELECTOLYTIC CONDUCTIVITY MEASUREMENT . . . . . . . . . . . . . . . . . . . . . 21932.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21932.2 Typical Conductivity Application Specifications . . . . . . . . . . . . . . . . . . . . . . . 21932.3 Conductivity Cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22032.4 Electrodeless Conductivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22132.5 Conductivity Monitors and Transmitters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22132.6 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22232.7 Maintenance and Calibration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224

33 WATER QUALITY GENERAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . 22433.1 Sample Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22433.2 Installation and Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22533.3 Calibration and Startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22533.4 Training . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225

APPENDIX F REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225

Figures2-1 Multi-analyzer Distributed System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34-1 Acceptable Sampling Areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74-2 Insertion Sample Open Probe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84-3 Fixed Sample Probe Open Flow Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84-4 Multiport Sampling Probe for Flue Gas Analysis . . . . . . . . . . . . . . . . . . . . . . . . . 94-5 Filter Probes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104-6 Pyrolysis Gas Sample Conditioner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114-7 Fast Loop Sampling System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124-8 Liquid Vaporization Sample Probe and Regulator Section

(High-temperature/Pressure Applications) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

x

9 Liquid Vaporization Sample Probe and Regulator Section(Low-pressure Applications) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

4-10 Stream Select System with Double Block-and-bleed . . . . . . . . . . . . . . . . . . . . . 204-11 Liquid Sample Recovery System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218-1 Photometric Analyzer Principle of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 438-2 Photometric Analyzer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 448-3 Chlorine Gas Spectrum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 458-4 Dual Frequency Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 458-5 Dual Path Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 458-6 Stages of Fire Associated with Solid Combustibles . . . . . . . . . . . . . . . . . . . . . . 488-7 Ionization Chamber Principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 488-8 Infrared Flame Detector with Lenses and Cathode Tube . . . . . . . . . . . . . . . . . . 498-9 Ultraviolet Detector Principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 508-10 Operating Elements of Combination Fixed-temperature and Rate-of-rise

Thermal Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 508-11 Typical Remote Head System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 528-12 Typical Multiple Head System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 528-13 Typical Tube Sampling System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 548-14 Typical Location for In-situ Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 548-15 Test and Calibration Means for Diffusion and Drawn Sampling . . . . . . . . . . . . 5610-1 High-temperature Oxidation Analyzer for Total Organic Carbon . . . . . . . . . . . 6110-2 Ultraviolet Promoted Oxidation Analyzer for Total Organic Carbon. . . . . . . . . 6210-3 Analyzer for Total Oxygen Demand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6310-4 Scattered Light Intensity Patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6410-5 Surface Scatter Turbidimeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6510-6 Ratio Turbidimeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6610-7 Amperometric Residual Chlorine Analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6710-8 Spectrophotometric Wet Chemistry Analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . 6810-9 Colorimetric Titrimeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6810-10 Absorption Spectrum for Hydrocarbons (Oils) . . . . . . . . . . . . . . . . . . . . . . . . . . 7010-11 Flame Ionization Hydrocarbons-in-water Monitor . . . . . . . . . . . . . . . . . . . . . . . 7211-1 Electromagnetic Radiation Spectrum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7611-2 Carbon Monoxide Spectrum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7611-3 Dual-beam Nondispersive Infrared Analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . 7711-4 Schematic of a Single-beam Filter-based Instrument . . . . . . . . . . . . . . . . . . . . . 7812-1 Ultraviolet Spectrum for Benzene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8012-2 Single-beam Ultraviolet Analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8012-3 Split-beam Ultraviolet Analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8013-1 Mass Spectrometer System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8113-2 Typical System for Spectroscopic-type Analyzers . . . . . . . . . . . . . . . . . . . . . . . 8314-1 X-ray Source, Sample Cell and Detector. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8414-2 Typical Sample System for X-ray Absorption-type Analyzers . . . . . . . . . . . . . . 8515-1 IMS Sample Cell Schematic Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8715-2 IMS-based CEM System Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8716-1 Example of the Chemical Information Available by Type for a Naptha Steam . 8817-1 Typical Stand-alone Gas Chromagraph (GC) with Optional Network. . . . . . . . 9217-2 Simulated Distillation Schematic. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9517-3 Gasoline Calibration Blend . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9617-4 D-3710 Calibration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9717-5 Comparison of D-86 and D-3710 Distillation Data . . . . . . . . . . . . . . . . . . . . . . 9817-6 Sample Chromatogram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10017-7 Typical Process Chromatograph System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

xi

8 Typical Chromatograph Analyzer Section. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10217-9 Gas Sample Valve with Double Block-and-bleed Arrangement . . . . . . . . . . . . 10417-10 Liquid Sample Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10417-11 Partial Analysis with Forward Flush . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10517-12 Partial Analysis with Back Flush . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10617-13 Total Analysis for Hydrocarbons and Fixed Gases . . . . . . . . . . . . . . . . . . . . . . 10618-1 Nomograph for Dew Points as a Function of Temperature and Pressure . . . . . 11318-2 Electrolysis Instrument . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11418-3 Liquid Sample Dry-gas Stripping System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11518-4 Infrared Analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11518-5 Aluminum Oxide Probe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11618-6 Flow Diagram of a Vibrating Crystal Moisture Analyzer . . . . . . . . . . . . . . . . . 11718-7 Sample Bypass System with Purge Gas Drying . . . . . . . . . . . . . . . . . . . . . . . . 11918-8 Moisture Generator for Calibration Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12018-9 Moisture Blender . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12018-10 Humidifier System for Calibration Check. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12119-1 Distribution of Products from Combustion of Various Fuels . . . . . . . . . . . . . . 12319-2 Typical Aqueous Electrochemical Cell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12319-3 Heated Probe-type Zirconia Electrochemical Oxygen Analyzer

Schematic Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12519-4 Magnetodynamic Paramagnetic Oxygen Analyzers . . . . . . . . . . . . . . . . . . . . . 12519-5 Thermal Paramagnetic Oxygen Analyzers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12619-6 Susceptibility Pressure Oxygen Analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12720-1 X-ray Absorption Analyzer System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13220-2 Infrared Absorption Analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13320-3 Mass Spectrometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13420-4 Ultraviolet Absorption Analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13520-5 Measurement of H

2

S in the Presence of SO

2

. . . . . . . . . . . . . . . . . . . . . . . . . . 13720-6 Measuring H

2

S in the Presence of SO

2

Using Two Ultraviolet Analyzers. . . . 13821-1 Pressure Sensing Pour Point Analyzer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14621-2 Motion Sensing Pour Point Analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14722-1 ASTM D2500 Freeze Point Apparatus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14822-2 ASTM D2386 Cloud Point Apparatus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14922-3 On-line Cloud Point Sample Cell Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . 15022-4 Cloud Point Schematic Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15122-5 On-line Freeze Point Analyzer Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15223-1 Initial Boiling Point Analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15423-2 Boiling Point Analyzer with a Smaller Boiling Pot . . . . . . . . . . . . . . . . . . . . . 15523-3 End Point Analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15623-4 Vacuum Distillation Analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15723-5 Thin Film Boiling Point Analyzer Flow Schematic . . . . . . . . . . . . . . . . . . . . . 15723-6 Typical Boiling Point Analyzer Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . 15924-1 On-line Ignition Type Flash Point Analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . 16024-2 Flash Point Detection by IgnitionHigh Temperature, Anti-coking Design . 16124-3 On-line Catalytic Reaction Flash Point Analyzer . . . . . . . . . . . . . . . . . . . . . . . 16224-4 On-line Flash Point AnalyzerTypical Installation . . . . . . . . . . . . . . . . . . . . . 16325-1 Continuous Reid Vapor Analyzer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16425-2 Micro-method Reid Vapor Analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16425-3 Kinetic Vapor Pressure Analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16526-1 Cool Flame Octane Analyzer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16726-2 Typical NIR Spectrum of a Reformulated Gasoline . . . . . . . . . . . . . . . . . . . . . 16926-3 Single Stream Sample System with Two Grab Sample Bottles . . . . . . . . . . . . 170

xii

4 Stream Switching and Sample Conditioning System . . . . . . . . . . . . . . . . . . . . 17026-5 Typical Installation of In-situ Probe/Fiber Optic System . . . . . . . . . . . . . . . . . 17126-6 Typical Calibration Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17226-7 Typical Distribution of Calibration Data from a Single Refinery . . . . . . . . . . . 17326-8 Calibration Data from Multiple Refineries . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17326-9 Typical Calibration Validation Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17426-10 Typical Routine Analysis Cycle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17526-11 Typical Calibration Update Procedure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17527-1 Typical Sampling System for High-viscosity Liquids . . . . . . . . . . . . . . . . . . . 18027-2 Typical Sampling System for Clean, Light Oils . . . . . . . . . . . . . . . . . . . . . . . . 18027-3 Typical Installation of a Capillary-type System . . . . . . . . . . . . . . . . . . . . . . . . 18127-4 Typical Installation of an Ultrasonic Probe Viscometer . . . . . . . . . . . . . . . . . . 18227-5 Tank Mounting for a Rotational Viscometer . . . . . . . . . . . . . . . . . . . . . . . . . . . 18227-6 Flowing Line Installation for Rotational Viscometer . . . . . . . . . . . . . . . . . . . . 18227-7 Viscometer Located Close to the Process Line . . . . . . . . . . . . . . . . . . . . . . . . . 18327-8 Viscometer Sample Line from Circulating Loop . . . . . . . . . . . . . . . . . . . . . . . 18327-9 Installation of Piston-type Viscometer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18428-1 Balanced Flow Vessel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18628-2 Typical Liquid Densitometer Sampling System . . . . . . . . . . . . . . . . . . . . . . . . 18628-3 Balanced Flow Tube. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18628-4 Typical Sampling System for Balanced Flow Tube . . . . . . . . . . . . . . . . . . . . . 18728-5 Industrial Specific Gravity Displacer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18728-6 Typical Hookup for Industrial Specific Gas Displacer . . . . . . . . . . . . . . . . . . . 18828-7 Chain-balanced-float Densitometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18928-8 Typical Hookup for Chain-balanced-float Density Instrument. . . . . . . . . . . . . 18928-9 Gamma-ray Density Gauge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19028-10 Vibrating Probe Densitometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19128-11 Typical Line-mounted Vibrating Probe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19128-12 Vibrating Spool Principle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19228-13 Sonic Liquid Densitometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19228-14 Gas Specific Gravity Balance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19328-15 Typical Hookup for Gas Specific Gravity Balance . . . . . . . . . . . . . . . . . . . . . . 19328-16 Gas Density Balance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19428-17 Typical Gas Densitometer Sampling System . . . . . . . . . . . . . . . . . . . . . . . . . . 19528-18 Fluid Drive Gas Gravitometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19628-19 Typical Sampling System for Gas Under Pressure . . . . . . . . . . . . . . . . . . . . . . 19628-20 Principle of the Rotating-element Type of Gas Densitometer . . . . . . . . . . . . . 19728-21 Typical Hookup for One Form of Rotating-element Densitometer . . . . . . . . . 19728-22 Thermal Conductivity Gas Densitometer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19828-23 Sonic Gas Densitometer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19829-1 Typical Color Analyzer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20229-2 Color Analyzer System Diagram. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20330-1 Ionization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20630-2 Ion Content in Water Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20730-3 Typical pH Scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20830-4 Piped Sample Stream at Atmospheric Pressure. . . . . . . . . . . . . . . . . . . . . . . . . 20830-5 Piped Main Process (or Sample) Stream. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20830-6 Tank at Constant Level. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20930-7 Tank at Variable Level, Submersion Assembly . . . . . . . . . . . . . . . . . . . . . . . . . 20930-8 Sampling Technique for Heavily Contaminated Oily Systems. . . . . . . . . . . . . 21030-9 Schematic Diagram of a Typical Electrode System . . . . . . . . . . . . . . . . . . . . . 21130-10 Combination pH Probe Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211

xiii

11 Sanitary pH Probe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21230-12 Field Repairable Probes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21330-13 In-line pH Probe. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21430-14 Retractable pH Probe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21430-15 Flow-through pH Probe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21531-1 Electrolysis Cell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21731-2 Galvanic Cell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21732-1 Conductivity Scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21932-2 Conductivity of Common Electrolytes vs. Weight . . . . . . . . . . . . . . . . . . . . . . 22032-3 Electrodeless Conductivity System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22232-4 Conductivity Cell with Universal Head. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22332-5 Conductivity Cell in Flow Housing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22332-6 Removable Type Conductivity Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22332-7 Electrodeless Conductivity Cell. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22332-8 Sample Cooler and Accessories. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224

Tables4-1 Darcy Pressure Drops vs. Line Size per 100 ft Sample LineGas Samples . . . . . 144-2 Darcy Pressure Drops vs. Line Size per 100 ft Sample LineLiquid Samples . . 154-3 Liquid Pressure Drops vs. Different Flow Velocities for a 100 ft Sample Line . . . 164-4 Comparison of Pressure Drops in PSI for Various Liquids vs. Common

Line Sizes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174-5 Comparison of Pressure Drops in PSI for Various Gases vs. Common

Line Sizes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184-6 Equivalent Feet of Straight Run Tubing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186-1 Analyzer Maintenance in Manhours per Year . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236-2 Checklist of Test Procedures for Analyzer Sample Conditioning Systems . . . . . . 356-3 Typical Checklist at Analyzer System Inspections . . . . . . . . . . . . . . . . . . . . . . . . . 3610-1 Characteristics of Turbidity Meter Types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6414-1 Typical Applications and Specifications of Spectroscopic and Other Types

of Analyzers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8618-1 Comparison of Moisture Analyzers by Type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11427-1 Constants Applicable to Viscometers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17731-1 Oxidation-reduction Potentials of Saturated Quinhydrone Solutions,

in Millivolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21932-1 Typical Ranges for Conductivity Cells. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221

xiv

1

Process Analyzers

SECTION APROCESS ANALYZER CONSIDERATIONS

A.1 Scope

Process monitors that measure and transmit informationabout chemical composition, physical properties, or chemicalproperties are known as

process analyzer systems.

Many ofthese systems were first

developed for laboratory analysis.Today they are primarily used as continuous on-line analyzers.

A process monitoring system usually requires a sampleconditioning system, a process analyzer, and one or more dataoutput devices. Properly designed systems also require over-all considerations as to calibration, utilities, sample disposal,safety, and systems packaging.

Process analyzers measure chemical concentrations orphysical or chemical properties that can be used as controlvariables instead of relying on indirect physical parameters,such as pressure, temperature, and inferred data from com-puter models. Process analyzer systems can provide a signifi-cant economic return when incorporated into processoptimization and advanced control loops or when used forproduct quality control.

This section will address the non-analyzer specific designfactors that must be taken into consideration in the design andimplementation of all analyzer applications.

Chapter 1 provides general information to be considered inthe design of analyzer systems.

Chapter 2 describes the requirement for analyzer system datamanagement.

Chapter 3 provides information on analyzer calibration andvalidation.

Chapter 4 provides extensive information on the properdesign of analyzer sample systems.

Chapter 5 describes the benefits of pre-packaging analyzersystems over field construction methods.

Chapter 6 provides information on the installation and main-tenance of analyzer systems.

Chapter 7 provides information on safety in the design ofanalyzer systems.

1 Analyzer Selection Design Requirements

1.1 ECONOMIC CONSIDERATIONS

Analyzer systems can improve product quality, increasethe yields of products with higher economic value, increaseproduct throughput and output, and reduce energy costs.

Process analyzer systems should be considered for productquality control when frequent and rapid measurements arerequired because of fast and substantial variations in processstream quality.

If an analyzer system is to be installed to improve opera-tional efficiency of a process unit, the installation should bejustifiable from an economic standpoint. Increased profitfrom improved efficiency combined with decrease in off-specmaterial produced must be weighed against the cost of install-ing, operating, and maintaining the system.

1.2 ENVIRONMENTAL AND SAFETY CONSIDERATIONS

Today, environmental standards are becoming more strin-gent. The use of analyzers for safety or environmental moni-toring should be considered for analytical applicationtechniques that comply with the regulations of the agenciesspecifying such monitoring and documentation requirements.

Process analyzers are used to detect hazardous plant condi-tions and for monitoring government-mandated requirementsconcerning pollutants in ambient air, stack emissions, andeffluent streams.

1.3 APPLICATION REQUIREMENTS

How the analyzer system will be used (for example, qualitycontrol, process control, and safety/environmental regula-tions) and what the analysis results are to be used for must beasked initially before selecting an analyzer.

Primary factors to be considered are as follows:

a.

Application method:

First a determination must be maderegarding whether a physical or chemical property or a com-position analyzer is required. Then a determination must bemade on the specific application method. A method is typi-cally selected for a particular measurement or analysisaccording to laboratory and/or process experience. b.

Repeatability and accuracy:

The design of all analyzerapplications should take requirements for accuracy and preci-sion into consideration. Emphasis is usually placed onanalyzer stability and repeatability of the measurement. Thecapability of the analyzer must match the requirements of theanalysis required.c.

On-stream factor:

A goal of 95% or greater on-stream fac-tor of on-line availability is generally desired. Analyzersexhibiting less than 95% are generally not considered reliableby operations and closed-loop control applications. On-stream factor is the total time the analyzer is operating reli-ably, relative to process operations. Reliability of the analyzer

2 ANSI/API R

ECOMMENDED

P

RACTICE

555P

ROCESS

A

NALYZERS

system, commitment of maintenance personnel, and ease ofmaintenance contribute to the on-stream factor.d.

Overall system response time:

This is the total timerequired to take a representative sample, condition it, analyzethe sample, and output the results.e.

Sample conditioning:

Most analyzer systems requirereliable samples to be conditioned so the sample will becompatible with the analyzer. The location of the sampletap in the process is important in obtaining a representativesample. A sample conditioning system must deliver a pro-cess sample in a timely manner, in which the componentsto be measured represent the actual process streamcomposition.f.

Installation:

Consideration should be given to area electri-cal classification, protection from the environment, ambienttemperature variation effects, ease of availability for mainte-nance, and sample disposal requirements.g.

Maintenance:

Process analyzers should be designed foreffective maintenance. The type of maintenance, frequency,and personnel requirements should be considered.h.

Operating costs:

These should include costs of utilitiesand consumables plus labor and materials for maintenance.i.

Safety/environmental requirements:

If an analyzer isrequired for monitoring pollution and/or the occupationalenvironment, the analyzer should comply with the appropri-ate regulations applicable to such measurements.

2 System Data Management Requirements

2.1 GENERAL

The transmission of the data is an important considerationin the design of the analyzer system. Three types of transmis-sions are common: analog transmission, digital transmission,and highway links. Consider 2.2 through 2.4 in reference tothese three types of transmissions.

2.2 ANALOG TRANSMISSION

The electronic output signal from the analyzer is a voltageor current proportional to the measured parameters in thestream. Discrete contacts are also usually available to monitorthe data validity and analyzer integrity.

2.3 DIGITAL TRANSMISSION

The transmission and communication of analyzers viadirect serial communications is versatile and accurate. Ana-lyzers equipped with one or more serial ports can be inter-faced to several types of devices. Data that is transmitted in aserial format can communicate with a printer terminal, centralprocessor unit, personal computer, host computer, or distrib-uted control system (DCS). Serial ports are also capable oftwo-way communications. The data messages communicated

are not limited to concentration values and may include suchthings as alarms, system status, data validation or calibrationcommands, program commands, and diagnostic maintenanceroutines such as reconstructed chromatograms for process gaschromatographs.

The results coming from the analyzers can include datavalidation status and hardware status information that can beused by the DCS for implementing process control strategies.

Typical alarms for data validation are as follows:

a. Tolerance against check or calibration sample.b. Excessive change of data output.c. Excessive baseline noise.d. Peak drift for gas chromatographs.e. Communication failure.f. EPROM error.

Typical alarms for hardware status information include thefollowing:

a. Loss of sample flow.b. Loss of utilities.c. Hardware failure.d. Loss of pressurization.e. Loss of power.

The interfacing of the analyzer communications system tothe host device must be coordinated between users and equip-ment suppliers to assure compatibility. The communicationmay require writing a driver program to collect and formatthe data so as to be compatible to the host device.

2.4 HIGHWAY LINK

For multi-analyzer distributed systems, where each ana-lyzer produces output data completely independent of anycentral programmer or central computer system, data high-ways are used for transmitting analytical data and analyzercommunications. The data highways allow many analyzersto communicate through one network to a central location.A distributed system typically may also contain a centraloperator station for analyzer management and maintenance.The communication requires simple installation of only twoto four wires for linking all the analyzers in the system. Pre-cautions must be made to protect this highway path fromthe risk of damage or failure so all communications andcontrol will not be lost. For example, if a redundant high-way is available, each path should be wired in differentphysical paths.

Figure 2-1 represents a general multi-analyzer distributedsystem with typical highway links. Most highway systemsthen link to a Distributed Control System through a commongateway with a standard communication protocol.

Remote links incorporated into analyzer highway systemscan include a modem link for remote factory maintenancesupport.

S

ECTION

AP

ROCESS

A

NALYZER

C

ONSIDERATIONS

3

3 Analyzer System Calibration and Validation

3.1 GENERAL

To determine whether an analyzer is performing properly,it should be checked against calibration/validation samples.

3.2 CALIBRATION3.2.1 General

Calibration is an important part of the startup, as well asthe continuing operation of a process stream analyzer.Depending upon the type of analyzer, its history, and howcritical its analysis may be, calibration can range from aquick-and-dirty check to see if the analyzer is operatingwithin acceptable limits, to a very careful fitting of multiplepoints to a standard curve.

This section discusses only general methods of calibrationbecause the types of analyzers are too numerous and varied togive specific details for each. The manufacturers instructionmanuals are usually detailed enough to determine the pre-ferred method for calibrating the particular analyzer.

3.2.1.1 Purpose of Calibration

Before an analyzer is shipped from the manufacturingfacility, it is operationally tested by the manufacturer to dem-onstrate performance to design specifications. This calibra-tion data can then be used as a basis for any and all futureoperation of that analyzer.

It will be necessary to calibrate or witness calibration dur-ing inspection at the manufacturers facility and also duringcommissioning. Calibration will also be required after amaintenance shutdown or after replacement of parts in the

Figure 2-1Multi-analyzer Distributed System

4 ANSI/API R

ECOMMENDED

P

RACTICE

555P

ROCESS

A

NALYZERS

sensing mechanism (such as light or power sources, detectorelements, or columns, in the case of a chromatograph). Pro-cess plant operators may also request a calibration (or re-cali-bration) as part of plant operations.

Quite often calibration is only a verification rather than anupdate or change in the analyzers calibration factor(s).Apparent disagreements between analyzer and laboratoryresults should be interpreted in terms of sampling techniquesthat may produce acceptable yet routine differences betweenthe off-line and on-line data. Historical records may be uti-lized to document acceptable differences and to indicatewhether the disagreement is an actual error or not (see3.2.3.5). Statistical Quality Control techniques should beemployed to determine if the analyzer should be re-calibratedor merely checked (i.e., calibration components are mea-sured, but the factors are not updated).

3.2.1.2 Personnel

In most plants, an analyzer maintenance specialist per-forms calibrations. Refer to Chapter 6 for the qualifications ofcalibration and commissioning personnel.

An understanding of the samples chemistry and the ana-lyzers physics will help in procuring suitable standardsand in calibrating the device. Laboratory personnelinvolved in preparing or analyzing calibration standardsshould also understand the principle or technique used inthe plant analyzer.

Familiarity with terminology associated with each type ofanalyzer [such as mole percent, liquid volume percent or PPM(v/v)] is important for performing a successful calibration.

The analyzer maintenance specialist should understand theprocess analyzers theory of operation. This can be useful indeciding whether a change in results is due to component fail-ure or aging.

The specialist should also understand the operation of thesample system associated with the analyzer, since problemswith calibration can also be problems of the sample systemitself.

3.2.2 Standards for Calibration3.2.2.1 Sources for Standards

An obvious source for calibration standards is a laboratoryanalysis of samples from the stream to be analyzed. Not soobvious is the necessity for obtaining the samples (more thanone) at the same sample point and under the same conditionswith special attention to the possibility of losses or changesresulting from handling (for example, pressure or temperaturechanges).

Multiple samples and replicate laboratory analyses, plusknowledge of the laboratorys confidence factor are needed totranslate the analysis to a standard value. Small differencesbetween the laboratory analytical method and the processanalyzers principle of operation should also be expected

when comparing results. The confidence factor will indicateif the results are reasonable.

A process line sample calibration technique uses labora-tory analyses of plant samples drawn during steady-stateoperation. Analyzer readings are noted and then used to makenew settings if significant differences are detected. Daily (orroutine) laboratory results are used to plot trends for compari-son with those of the process analyzer; however, the analyzermay have inherent drift tendencies that must be corrected foron a more frequent basis to achieve the highest accuracy.

A reference sample can be either a retained process streamtaken during normal or desirable operation, as describedabove, or a synthetic blend prepared, analyzed, and certifiedby a commercial supplier. The synthetic standard may be nec-essary for materials that react with other ingredients when leftstanding, or when cooled, or to allow calibration of a materialthat polymerizes or decomposes with time. Pure com-pounds (gas or liquid) can be used to set the span or full-scale reading for some analyzers just as pure air or nitrogencan be used to obtain a zero setting. The retained processstream can serve as an inexpensive secondary standard toverify analyzer operation, using the expensive and complexsynthetic blend only for occasional re-calibration.

3.2.2.2 Equipment for Calibration

Cylinders containing the calibration standard are oftenstored at the analyzer location. Some provision should bemade for protecting the cylinders from the elements and fromtampering. Records of the standards analysis should be filedfor future use since tags or stencil markings on the cylinderscan fade or become illegible. Temperature-sensitive samples,vapor or liquid, must be stored and used under their designconditions.

Regulators should be reserved for standard service tominimize contamination errors. Tools required to connect anddisconnect standard sources should be a part of the operatingsupplies. Thermometers, pressure gages, flow-measuringdevices, and other tools are often needed to verify calibration.

A better-equipped facility may include equipment for blend-ing check standards, such as absolute pressure gages, vac-uum pumps, cylinders of pure gases to make gas blends, andcontainers of pure hydrocarbons to make liquid mixtures.

A supply of small cylinders (for example, 100 milliliters)to transport pressurized samples to a laboratory for checkingcan be useful for quick verification.

3.2.3 Calibration Procedures

If service work that can change the output signal of an ana-lyzer is to be performed, the operations personnel should benotified. If the analyzer is on control or alarm status, stepsmust be taken to transfer it to a manual or hold mode.

S

ECTION

AP

ROCESS

A

NALYZER

C

ONSIDERATIONS

5

All calibration procedures should be well documented in awritten step-by-step form to ensure repeatability betweentechnicians.

3.2.3.1 Automatic Calibration Systems

If the analyzer system is automated to the extent that itperiodically (daily or weekly) checks its output readingagainst a standard, personnel servicing the analyzer may berequired only to check the flow rate or pressure gage read-ings or to verify the operation of solenoid valves. Pro-grammed limit values can be used to alert the user toabnormal readings.

A semiautomatic system allows the service person or pro-cess operator to check or update analyzer readings. Again,sample pressure or flow should be checked visually or by theprogrammed limits.

A preliminary check of the standard(s) should includedetails such as the age, pressure, or volume remaining and theambient temperature.

3.2.3.2 Zero/Span Calibration Systems

Some analyzers are calibrated by adjusting the output read-ings for a fluid containing none of the component of interest(zero) and then adjusting the output readings for another fluidcontaining a full-scale amount of the component (span). Forsuch analyzers, the following calibration procedures are rec-ommended:

a. Turn off the process sample to the analyzer.b. Turn on and adjust the flow of the zero standard.c. When readings stabilize, make adjustments if necessary.d. Turn off the zero standard.e. Turn on and adjust the flow of the span standard.f. When readings stabilize, make adjustments if necessary.g. Turn off the span standard, and turn on the process streamflow.

Several iterations will be required if the zero and spanadjustments are interactive.

3.2.3.3 Complex Analyzer Systems

In more complex analyzer systems, standards containingone or more components of interest are introduced to set orverify digital or analog factor values. For such analyzers, thefollowing calibration procedures are recommended:

a. Set the analyzer controls to calibration or manual mode.b. Turn off the process sample to the analyzer.c. Turn on and adjust the flow of the standard. (If the calibra-tion mode computes new factors, compare the new factorwith the old factor.)

d. Run replicate analyses if output values differ from thestandard value.e. Adjust factor settings or enter new data to the controldevice.f. Turn off the standard and turn on the process stream flow.

CAUTION:

Before updating the value of the latest factor orchanging the analyzer calibration, consider the quality of thestandard and the calibration history of the analyzer. Somestandards can change with age. A laboratory re-calibration,especially for blended standards, is recommended at leastevery 3 months.

3.2.3.4 Alternative Forms of Calibration Check

In analyzer systems where the standard is treated as a pro-cess sample, the standard is introduced when the system is ina normal mode (except that the output is off-line). Readingsare compared with the known values of the components orquality of interest. For such analyzers, the following calibra-tion procedures are recommended:

a. Shut off plant sample flow.b. Turn on the standard and adjust the flow.c. When the analyzer readings stabilize, compare readingswith the known values.d. Make adjustments.e. Rerun the standard to verify the new settings.f. Turn off the standard and turn on the plant sample.g. Put the analyzer system back in operation.

3.2.3.5 Calibration History

A schedule of routine calibration checking should be set upas a part of the analyzers maintenance procedures. Recordsof monthly, weekly, or even daily checks serve to increase theusers confidence in the analyzer, as well as to alert the tech-nician to signs of impending analyzer failures. A welldesigned, stable analyzer may show no change between peri-odic calibration checks. The checks then serve as a verifica-tion of the equipments competence. In the case of ananalyzer malfunction, the calibration procedure becomes apart of troubleshooting, either by showing an analyzer fault ordirecting attention to other components, such as the samplesystem or recorder.

A maintenance history can be brief or extensive but as aminimum should include a log of repair, component replace-ment, calibration, and consumables replacement, completewith dates and technicians names for each entry.

Many users set up individual folders for each analyzer as ameans of storing these documents. Some have establishedcomputer programs for accumulating maintenance historyand costs and for scheduling preventive maintenance.

6 ANSI/API R

ECOMMENDED

P

RACTICE

555P

ROCESS

A

NALYZERS

3.2.4 Calibration Criteria

3.2.4.1 Accuracy

The main reason for calibrating an analyzer is to ensurethat the analyzer provides an accurate result. In most cases,accuracy is limited by the standard analysis or laboratoryresults. If an analyzer is calibrated to an erroneous standard,the output is in error even though it may be useful for follow-ing changes in the process. The cost of achieving a certaindegree of accuracy may be a limiting factor. If high accuracyis required, replicate analyses of standards, verificationthrough parallel lab analyses, and cross-checks with the pro-cess operation are important parts of the analyzer mainte-nance program. The user must establish acceptablecalibration accuracy criteria.

3.2.4.2 Repeatability and Reproducibility

The repeatability of a process analyzer is its ability to givethe same reading, time after time, using a constant sample.Repeatability can be stated as the difference between succes-sive results that would be exceeded only 1 case in 20 (that is,a 95% confidence factor).

Reproducibility is the expected error between two differentsources (for example, the error between a laboratory resultand the analyzer result or results from two analyzers cali-brated from the same standard).

3.2.4.3 Linearity

The linearity (or non-linearity) of an analyzer will deter-mine the number of standards required for complete calibra-tion. In addition to zero and span standards, intermediateconcentrations may be required to establish a curve-fit ofdetector response to concentration.

Although not a typical specification, linearity might bedefined as the reading error at 50%, for example, on an ana-lyzer calibrated at 100%. Linearity error problems usually areminimized if the analyzer can be calibrated at a value veryclose to the normal process concentration.

3.3 VALIDATION

Validation

is observing and noting the difference (if any)between the analyzer reading and the agreed analysis of astandard introduced into the analyzer, but with no adjustmentmade to the analyzer. When a difference is recorded (as on acontrol chart), random statistical error can be estimated andaccurate adjustments made. This avoids the practice of toofrequent adjustment in an attempt to tune out normal systemfluctuations.

Where the repeatability of the analyzer is closer than thereproducibility of the reference laboratory test, calibration/

validation samples should be multi-tested to reduce the stan-dard error of the mean.

Detailed information on the validation of analyzers can befound in ASTM D-3764

Standard Practice for Validation ofProcess Analyzers

.

4 Sample Conditioning

4.1 GENERAL

Sample conditioning systems are comprised of all the com-ponents necessary to extract a representative sample and tocondition the sample for measurement by the analyzer. Thedesign of the total sample conditioning system must be engi-neered for each specific application.

The sample conditioning system assembly tends to becomplex (actually small chemical processes with control sys-tems) and is often the least reliable segment of an analyzersystem.

It is important that all factors that influence an overall sys-tem and the operation of an analyzer be given thorough con-sideration. Such factors as unknown process conditions,process upsets, and contaminants can lead to poor designs.

4.2 FUNCTIONS OF A SAMPLE SYSTEM

The functions performed by the sample conditioning sys-tem as the interface between the process and the process ana-lyzer include the following:

a. Taking and delivering a representative sample from theprocess.b. Transporting the sample from the sample tap to the ana-lyzer and from the analyzer to the waste disposal and/orprocess return point.c. Conditioning the sample by adjusting the pressure, tem-perature, flow rate, filtering, and phase maintenance of thesample as required to make the sample compatible to the pro-cess analyzer.d. Sample-stream switching and calibration switching intothe analyzer.e. Design incorporates capability for ease of maintenance,cleaning, or (when needed) flushing the entire system.

4.3 DESIGN FACTORS4.3.1 Sample Stream Composition

The complete stream composition of all the componentsand contaminants must be considered. Some contaminants,such as solids or entrained liquids in a gaseous stream, mayhave to be removed by the sample system. The process condi-tions and range of all components during normal and espe-cially abnormal conditions (such as startup, shutdown, ratechange, and so forth) must be considered for the analyzerapplication and sample system design.

S

ECTION

AP

ROCESS

A

NALYZER

C

ONSIDERATIONS

7

4.3.2 Sample Point Location

The following factors should be considered in determiningthe optimum sample point location:

a. Locate the sample tap in the process stream where a repre-sentative sample can be withdrawn.b. It is important to locate the sample tap where correctiveaction may best be achieved in the process. Locations down-stream of large vessels or accumulators should be avoideddue to an increase in lag time that is introduced by the signifi-cant volume increase.c. Locate the analyzer as near as practical to the sample pointto minimize sample transport time.d. Location should be considered to offer significant differ-ential pressure if the sample is returned to the process. Avoidsample points and returns around process control valves.Sample and return points around control valves present twoproblems: the sample bypasses the valve when it should beclosed and there is little or no sample bypass flow when thecontrol valve is wide open.e. Locate the sample tap for ease of cleaning or maintenanceand means of access to the sample point. Sample taps shouldbe located such that cherry pickers or ladders are not requiredto reach them.f. Locate the sample point where the process reaction ormixing is stable, and avoid sample point location wheremixed phases may exist.g. Locate the sample tap on the top or side of horizontal pro-cess lines, and horizontally in vertical process lines tominimize poor sampling. See Figure 4-1.

4.3.3 Sample Probes

Sample probes should be used because they provide a morerepresentative sample due to the higher flow rates away fromprocess pipe walls.

Note: Process lines smaller than 2 in. usually do not require a sampleprobe. If a probe is required for small diameter lines, the line may beswaged up to 3 in. or larger with a spool piece to allow a probe to beinserted.

Sample probes significantly reduce wall contaminatesand particulates and act as a first

stage of filtration and con-ditioning. Special design considerations are required whenprocess velocities are excessive (which may require thick-walled probes and in high temperature applications). Cor-rosive service or high temperatures may require specialalloys or materials. Flanged thermowells are often used assample probes by merely cutting the end off at a 45 angle.The probe is positioned 180 degrees from the process flowto minimize particulate matter in the extracted sample.Types of sample probes include those discussed in 4.3.3.1through 4.3.3.3.

4.3.3.1

Open probes

(see Figures 4-2 and 4-3) are typicallymade of short lengths of stainless steel pipe or tube,

1

/

4

or

3

/

4

in. outside diameter and used at temperatures to approxi-mately 1000F (540C). Insertion probes should have amechanical restraining device to prevent the probe fromblowing out when the packing gland is loosened. To preventprobe damage, all sampling probes should have a means tojudge when the probe is pulled out past the valve.

Figure 4-1Acceptable Sampling Areas

8 ANSI/API R

ECOMMENDED

P

RACTICE

555P

ROCESS

A

NALYZERS

Figure 4-2Insertion Sample Open Probe

Figure 4-3Fixed Sample Probe Open Flow Design

S

ECTION

AP

ROCESS

A

NALYZER

CONSIDERATIONS 9

4.3.3.2 Multiport sample averaging probes (see Figure 4-4) are used to obtain a sample whose composition is an aver-age of that existing across the entire duct. Averaging is notnormally attempted in ducts under 2 ft in diameter. Multipleprobe sample averaging is frequently used in flues and stacksof large boilers and heaters in which stratification may be aproblem or where required by compliance regulations. Thepreferred insertion length L and the maximum number ofentry holes may be obtained from Figure 4-4.

4.3.3.3 Filter probes are generally used in gas streams suchas combustion applications when the stream contains signifi-cant quantities of particulate material. The filter materials usedare primarily sintered or woven stainless steel and variousceramics. These probes must always be located in the processduct in a manner that minimizes their exposure to particulatematter, or else frequent cleaning will be required. Locating theprobe inside and just downstream of a bend, or adding bafflesjust upstream of the probe minimizes the probe exposure (seeFigure 4-5).

A filter probe must always be operated at a temperaturewell above the dew point temperature of the stream in whichthe probe is inserted. Filter probes can be cleaned by removalof the probe from service; however, a more common methodis a blow-back system, which introduces air, nitrogen, or

steam into the sample line to blow back through the filter inthe reverse direction. This may be done manually when thesample flow begins to drop to unacceptable levels or automat-ically at preset intervals.

Note: Blow-back gas should be above the dew point to prevent tem-perature condensation in the sample lines or filter probe, and must becompatible with the process stream.

4.3.4 Sample Tap Primary Conditioning

Installation of primary conditioning systems at the sampletap typically allows for more reliable operation of extremelydifficult samples that cannot be transported easily to a remotesample conditioning system.

Pyrolysis furnace effluents, regenerator gas from FCCUand reformers or other hot gases with condensable material,particulate matter, and catalyst fines are examples requiringprimary sample conditioning in order to maintain a reliablecontinuous sample draw-off without plugging. A filter refluxcolumn is mounted directly on the process line shut-off valve.The sample is cooled, and the condensable material refluxwashes down the solids back into the process line, with aclean saturated sample coming out of the top of the column tothe analyzer. Depending on the amount of condensable mate-rial available in the sample, steam can be added to the bottom

Figure 4-4Multiport Sampling Probe for Flue Gas Analysis

10 ANSI/API RECOMMENDED PRACTICE 555PROCESS ANALYZERS

of the column to provide additional condensable material tothe reflux and to dilute the acids formed in the process (seeFigure 4-6).

Remote pressure let-down and vaporizer regulator stationsare another type of primary conditioning system. These sta-tions must be mounted near the sample tap to flash liquidsamples and reduce lag times by controlling the sample pres-sure before transport to the analyzer location. Insulation of aheated enclosure may be required on these installations if thesample dewpoint temperature cannot be maintained.

4.3.5 Sampling Time Dynamics and Transportation Lag Times

In some installations, where the analyzer and sample sys-tem must be located at a distance from the sample point, thesample transport time must be considered. The time neces-sary to transport the sample to the analyzer can in some casescontribute the largest share to the overall system dead-time orturnaround time. Turnaround time is defined as the total time

of sample system lag, dead-time, and the analyzer responsetime.

A convenient means for reducing this transport lag is theuse of a fast loop (see Figure 4-7) between the process equip-ment, an intermediate location (commonly just outside theanalyzer shelter), and a low pressure return point in the pro-cess where the sample can be returned.

Sample transport time, or lag time, is a function of the sam-ple line length and diameter, the absolute pressure in the line,and the sample flow rate. Sample transport time is simply thetotal volume of the sample line divided by the average flowrate in the line. The lag time can be calculated with the aid ofthe following equations:

tlag(liquid) = (1)

tlag(vapor) = (2)

Figure 4-5Filter Probes

V( ) L( )Flow rate------

api rp 0555 process analyzers (2001)

Documents