low-pressure excess flow natural gas valves, uniform ... · 2.2 spitzglass formula the design of...

LOW-PRESSURE EXCESS FLOW NATURALGAS VALVES

UNIFORM PLUMBING CODE APPLICATIONREQUIREMENTS

Prepared For:

Carl StrandStrand Earthquake Consultants

1436 S. Bentley Avenue, #6Los Angeles, CA 90025

and

James C. McGillSmart Safety Systems

4312 Lisa DriveUnion City, CA 94587

Prepared By:

J. Marx Ayres, P.E.Consulting Mechanical Engineer

1180 South Beverly Drive, Suite 600Los Angeles, California 90035

(310) 553-5285

January 21, 2002

Low-Pressure EFVs

Section

Table Of Contents

Table of Contents

Page

Table of Contents i

Tables & Figures (see attached) iiE t· S "'f'xecu Ive ummary 111 IVAcknowledgements V

1 Introduction 1-1

1.1 Background1.2 Purpose1.3 Excess Flow Valves

2 Calculations 2-12.1 UPC Requirements2.2 Spitzglass Formula2.3 Pipe System2.4 Certifications2.5 Spread Sheet Calculations

3 Discussion 3-1

4 Conclusions & Recommendations 4-1

Appendices A & B

J. Marx Ayres, P.E. Page i

Low-Pressure EFVs

Tables

Tables & Figures

Table of Contents

Page

2 - 1 Low-Pressure EFVs 2 - 42 - 2 UMAC Quake Breaker At Meter 2 - 92 - 3 UMAC Quake Breaker At Meter & At Each Appliance 2 - 112 - 4 Sanders At Meter 2 - 132 - 5 Sanders At Meter And At Each Appliance 2 - 152 - 6 UMAC Quake Breaker At Meter & Magne-Flo At Each Appliance ..2 - 172 - 7 Sanders At Meter & Magne-Flo At Each Appliance 2 - 192 - 8 Pressure-Drop Calculations Without EFVs 2 - 21

Figures

2 - 1 Model of Residential Piping System 2 - 52 - 2 Isometric Piping Diagram of EFV At Meter 2 - 62 - 3 Isometric Piping Diagram of EFV At Meter & At Each Appliance 2 - 72 - 4 Isometric Piping Diagram Without EFV 2 - 82 - 5 UMAC Quake Breaker At Meter 2 -102 - 6 UMAC Quake Breaker At Meter & At Each Appliance 2 - 122 - 7 Sanders At Meter 2 - 142 - 8 Sanders At Meter & At Each Appliance 2 - 162 - 9 UMAC Quake Breaker At Meter & Magne-Flo At Each Appliance 2 -182 - 10 Sanders At Meter & Magne-Flo At Each Appliance 2 - 202 - 11 Pressure-Drop Calculations Without EFVs 2 - 22

J. Marx Ayres, P.E. Page ii

Low-Pressure EFVs

Executive Summary

Executive Summary

The performance of low-pressure gas systems in buildings during earthquakes, and the

potential for fire due to pipe breaks or leaks, are vital public life/safety issues. Manufactured

products designed to shut-off or limit the supply of gas during an earthquake have been

developed and installed. Earthquake-actuated seismic gas shut-off valves (SGSVs), which are

generally installed downstream from the gas utility meters, have been mandated by some

Building Codes. Excess flow valves (EFVs), which are designed to limit the flow of gas when

the pressure-drop across the valves exceeds their manufacturer's specified limit, have been

developed for installation downstream from the meter or at each flexible appliance connector.

The installation and operation of gas systems on customers' premises is regulated by the

National Fuel Gas Code and local Building Codes. The Uniform Plumbing Code (UPC) requires

that each low-pressure gas system be so designed that the total pressure drop between the

meter (or other point of supply) and any outlet, when full demand is being supplied to all outlets,

will at no time exceed 0.5" of water column (WC) pressure. For low-pressure (6" to 8" WC)

systems with 250 CFH maximum demand and 250 Ft. maximum length from the meter (or other

point of supply) to the most distant outlet, pipe sizing tables are provided. The UPC also

provides for pressure-drop calculations on each pipe section, fitting, valve, or control device,

following basic fluid flow engineering formulas to meet the 0.5" maximum total pressure-drop

criteria.

The pressure drops required to actuate (Le., close) EFVs are determined by certified testing

laboratories following the CSA U.S. No. 3-92 Requirements. The purpose of this study was to

determine the impact of these valves when applied in a model residential building with 7.0" WC

pressure gas service. Plan check calculations were prepared for the gas system with and

without EFVs (manufactured by UMAC, Sanders, & Brass Craft / Magne-Flo) located: (1)

downstream of the meter, and (2) at the meter and at each appliance connector. Spitzglass

formula pressure-drop calculations for all components in the system were prepared, and the

results of the spread sheet calculations are presented in tabular and graphical form. Difficulties

in obtaining EFV and appliance - connector pressure - drop data are discussed.

J. Marx Ayres, P.E. Page iii

Low-Pressure EFVs

The study's conclusions and recommendations are:

Executive Summary

• When EFVs are installed in typically sized low-pressure gas systems, the total pressure drop

of the systems will exceed the UPC maximum allowed 0.5" WC.

• Building Codes should require plan checks for any low-pressure gas systems using one or

more EFVs.

• Pressure drops across flexible appliance connectors should be listed with a defined number

and radii of bends or loops.

• For flexible appliance connectors that are provided with an attached or encapsulated EFV,

the pressure drops should be listed both with and without the EFV.

J. Marx Ayres, P.E. Pageiv

Low-Pressure EFVs

Acknowledgements

Acknowledgements

This report was prepared by J. Marx Ayres, P.E., Past President of Ayres, Ezer & Varadi,

Consulting Engineers, now renamed AEV Inc. Technical assistance was provided by Ivan

Varadi, C.I.P.E., Vice President and Director of Plumbing & Fire Protection Engineering at AEV.

The assistance of Carl Strand, President of Strand Earthquake Consultants, in providing

background information, product brochures, and test reports obtained from State agencies is

gratefully acknowledged.

J. Marx Ayres, P.E. Page v

Low-Pressure EFVs

1.1 Background

Section 1Introduction

Introduction

The performance inside buildings of gas systems during earthquakes and the potentialfor fire due to failure of one or more system components (pipe segments, fittings, valves,flexible appliance connectors, or appliances), has been the subject of intense study bygovernment agencies, utilities, researchers, and design engineers. Manufacturedproducts designed to shut-off or limit the supply of gas during an earthquake have beendeveloped and installed.

Seismic gas shut-off valves (SGSVs), which close when they detect a certain level ofground or pipe shaking, are generally installed downstream from gas-utility meters in low- pressure lines serving buildings. Excess flow valves (EFVs) are designed to restrict theflow of gas when they detect a sufficiently large drop in pressure on the downstreamside of the valve, which may occur due to a downstream pipe failure. EFVs, normallyused in gas-utility high-pressure lines upstream from the meter, have been developed forapplication downstream from the meter (like the SGSVs) and also at each applianceconnection.

Building Codes & Standards, which are designed to regulate an industry and protect thepublic, are revised and upgraded after each major earthquake. Most of the Standardsdeveloped by professional organizations follow strict consensus procedures that definemanufacturing performance and testing requirements. Building Codes define theminimum standards and construction procedures allowed by the governmental agencyhaving jurisdiction. Organizations that develop and publish Standards, Codes, andCertifications that are of interest in this study include:

• American Gas Association (AGA)• American National Standards Institute (ANSI)

• American Society of Civil Engineers (ASCE)

• American Society of Heating, Refrigeration and Air-Conditioning Engineers(ASHRAE)

• American Society of Plumbing Engineers (ASPE)• California Division of the State Architect (DSA)• Canadian Gas Association (CGA)• Canadian Standard Association (CSA)• International Approval Services (IAS)

• International Association of Plumbing & Mechanical Officials (IAPMO)• National Fire Protection Association (NFPA)

On July 3, 1997, the CSA, an independent North American Standards-development,product-certification, and management-systems-regulation organization, acquired IAS(formerly a joint venture of AGA and CGA).

The professional organizations that develop Standards operate through Technical orTask Committees (TC's) where members are appointed to represent most of the

J. Marx Ayres, P.E. Page 1 -1

Low-Pressure EFVs Introduction

interested parties in a specific industry, (Le., manufacturers, application designengineers, users, installers, and governmental agencies). The industry discussionsregarding SGSVs and EFVs are currently focused in the ASCE-25 Task Committee onEarthquake Safety Issues for Gas Systems. The ASCE-25 TC is an ad hoc committeeconsisting of ASCE-25 members and others, and was formed by the California SeismicSafety Commission (SSC) to study the use of seismic gas safety valves as well asproducts and methods related to earthquake safety.

1.2 The purpose of this study was to assist in the evaluation of EFV applications in buildinglow-pressure natural gas systems. The specific assignment was to prepare plan-checkcalculations for a typical residential installation using the test results submitted by themanufacturers to the California Office of the State Fire Marshal and the DSA. Thetechnical approach was to select a model building and prepare pipe-sizing calculationsfor the gas system both with and without EFVs. The residential system shown on page105 of the 1979 edition of the Uniform Plumbing Code (UPC) was selected as the model.

The pressure-drop calculations presented in this study are limited to natural gas systemswith specific gravity of 0.6 at 60°F. See Section 2.0. The component and systempressure drops using natural gas at other specific gravities, and / or vaporous propanegas with specific gravity of 1.53 at 60°F., were not a part of this study.

1.3 Low-Pressure EFVs

Low-pressure (LP) EFVs are designed for installation downstream of the gas-utilitypressure regulator and meter, or at the end of the gas line after the gas cock at the entryto the flexible appliance connector. They are constructed with a mechanical means thatis intended to prevent gas flow in excess of 80% to 110% of their manufacturer'sspecified closing flow rate at the system's normal operating pressure. Themanufacturers of LPEFVs included in this study are UMAC (Quake Breaker, GasBreaker, & GASP brands), Sanders Valve, and Brass Craft (Magne-Flo brand).

J. Marx Ayres, P.E. Page 1 - 2

Low-Pressure EFVs

2.1 UPC Requirements

Section 2Calculations

Calculations

The requirements for gas pressure regulators and piping size are based on a natural gashaving a specific gravity (SG) of. 0.60 at standard conditions (60°F and 14.7 Psi)supplied at 6" to 8" WC pressure at the outlet of the meter (UPC Section 1216.0). Themaximum demand shall not exceed 250 cubic feet per hour (CFH), and the maximumlength of piping between the meter and the most distant outlet shall not exceed 250 feet.The size of each section of pipe and each outlet of any system shall be determined bymeans of UPC Table 12-3 (Section 1217.1).

UPC Table 12-3 is based on the maximum delivery capacity in CFH of iron pipe size(IPS) carrying natural gas with a maximum pressure drop of 0.5" WC pressure. Thistable-simplified "longest run" method was developed by NFPA and AGA (National FuelGas Code NFPA 54; ANSI Z 223.1). For conditions other than those covered in UPCSection 1217.1, the size of each piping system shall be determined by standardengineering methods acceptable to the Administrative Authority. Each such systemshall be so designed that the total pressure drop between the meter (or other point ofsupply) and any outlet, when full demand is being supplied to all outlets, will at no timeexceed 0.5" WC pressure. This type of calculation is often referred to as the "pressuredrop" method.

2.2 Spitzglass Formula

The design of piping systems for gas is a fluid-flow problem. Where the required flowrate is determined, the pressure losses due to friction are calculated, and the requiredresidual pressure at each appliance is known. Using basic engineering formulae, theengineer can tabulate the various quantities, establish the pipe sizes for each section ofpiping, and determine the pressure and flow rate at any point in the system. The flowrate of gas (at standard conditions) in a pipe with pressures not exceeding 1 Psi (28"WC) can be computed using the following Spitzglass formula (ASPE Data Book, 1999,Page 8, Equation 1-24):

Q = 3550 K I hSL

Q - 3550 K (.ll-\Yz- SU

[ d5h ] ~

Q = 3550

SL (1 + 3;t + O.03d)Where

Q =Gas flow rate (In CFH)d

=Inside pipe diameter (In Inches)h

=Pressure drop (In Inches WC)S

=Specific gravity of the gasL

=Length of pipe (In Feet)


Low-Pressure EFVs Calculations

The length used in the formula must be corrected to allow for the additional resistance toflow caused by valves and fittings in the piping. The pressure drops expressed in"equivalent lengths" of pipe for standard pipe fittings are available in the UPC and otherpiping design handbooks. Pressure drops through control valves and other devicesinserted into the system should be obtained from their manufacturer's published data,because flow patterns through valves can vary significantly.

2.3 Pipe System

The model piping system with connected appliances and pipe sized by the "longest run"method per UPC Table 12-3 is shown in Figure 2-1. The typical residential customerreceives gas from the serving utility at 6" - 8" WC pressure. In California, the SouthernCalifornia Gas Company (SCG) provides gas at 8" WC pressure to their residentialcustomers and Pacific Gas & Electric (PG&E) provides gas at 7" WC pressure. Forpurposes of this study, the pressure-reducing valve (regulator) was set at 7-1/2" WCpressure and 0.5" WC pressure drop was assumed through a typical meter. Thus thepressure entering the piping system is 7" WC. The piping is terminated at eachappliance with a shut-off cock and a flexible metal connector. Isometric drawings of thepiping system with EFVs are shown in Figures 2-2 and 2-4.

The UPC limits the piping system's total pressure drop from the meter to the outlet to amaximum of 0.5" WC. The outlet is not clearly defined in the Code, but it is interpretedto mean the shut-off cock at the end of the piping system. If an EFV is inserted into thepiping system at the appliance, it would be located upstream from the shut-off cock. Ifthe EFV is located downstream from the shut-off cock, its pressure drop must beincluded in the 0.5" WC maximum total pressure loss. Note that in the followingisometric piping diagrams, the EFV is located downstream from the shut-off cock as apractical matter to facilitate maintenance or replacement.

2.4 Certifications

The design, construction, and performance of all gas-system components (appliances,flexible connectors, SGSVs, EFVs, and other devices) must be tested following apublished standard and certified (listed) by a recognized agency. In the U.S. gasindustry, the criteria is established in the National Fuel Gas Code, (ANSI Z 223.1/NFPA54) and other ANSI.CGA standards. The manufactured products are tested by approvedlaboratories (such as AGA) to assure that they meet that criteria. The currently acceptedcriteria for EFVs are published in the CSA U.S. No. 3-92 Requirements. It should benoted that the Requirements were developed by the CSA non-consensus "industrystandard" development function and not their "consensus standard" developmentfunction.

The performance of listed appliance connections for low-pressure (8" WC or less)systems based on 0.2" WC pressure drop for various lengths and flow rates, arepresented in UPC Table 12-10. The appliance connectors offered by one manufacturer(Brass Craft) are tested and listed per ANSI Z 21.24./ CGA 6.10 for pressures that donot exceed 0.5 psi (14" WC) and are based on 0.5" WC pressure drop for variousstraight lengths and flow rates (expressed in BTU/HR with 0.64-SG, 1000-BTU/CF gas).See Appendix A.



The performance data and description of the LPEFVs included in this study arepresented in Table 2-1. See Appendix B for the available manufacturer's literature andCSA-certification test data. Note that the UMAC test data are based on 0.6-SG with

1000-BTU/CF gas; and the Sanders and Magne-Flo test data are based on 0.64-SG1000-BTU/CF gas. The calculations shown in Section 2.5 used the CSA's 0.64-SGbased pressure drop (h) without correction to 0.6 SG, which would have an insignificantimpact on the calculated pressure drops. Calculations were also prepared so theperformance of the various LPEFVs could be compared using the same values for SGand BTU/CF.

2.5 Spread-Sheet Calculations

The Spitzglass formula used in the Excel Spread-Sheet calculations is as follows:

Q =3550(K){(h )/(S)(L)y.5K

={D".5/(1 +(3.6/D)+(0.03)(D)]}".5

Where Q

=Gas flow rate (In CFH)D

=Inside pipe diameter (In Inches)h

=The pressure drop (In Inches WC)S

=Specific gravity of the gasL

=Length of pipe (In Feet)

The calculations were performed using the pipe sizes shown in the model depicted inFigure 2-1 with (1) an EFV only at the meter, and (2) an EFV at the meter and at eachappliance. See piping isometric diagrams shown in Figures 2-2 and 2-3. The datapoints shown on the diagrams are identified as sections in the left column of Tables 2-2through 2-8, which present the calculated pressure drops in the longest run (i.e., thepiping between the meter and the most remote outlet). Pressure drops that wereinterpolated from Table 2-1 were used for the UMAC, Sanders, and Magne-Flo EFVs.Flexible-connector pressure drops from Brass Craft for straight-length applications wereused for all flexible connectors.

Pressure drops calculated for the model system without the EFVs are presented in Table2-8. Note that the 0.49561" WC total pressure drop for the piping system without flexibleconnectors meets the UPC maximum 0.5" WC requirement. This would be expectedbecause the lines were sized per UPC Table 12-3, which was designed to help preventlow-pressure systems from exceeding 0.5" WC total pressure-drop. Also note that all ofthe systems with one or more EFVs exceed the UPC 0.5" WC maximum total pressuredrop requirement. The system pressure drops for the various configurations arepresented graphically in Figures 2-4 through 2-11.


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Low-Pressure EFVs

Table 2 - 2

Pressure-Drop Calculations WithUMAC Quake Breaker At Meter

Calculations

SECT Qd NOMINALd ACTUALLSKhRES PRESSCFH

ININFT INWCINWC1-2

22511.04910.60.533470.008476.991530863liT"

22511.0493.50.60.533470.029646.9618888822-3

22511.04910.60.533470.008476.953419745fll"

22511.04920.60.533470.016946.9364814703-4

22511.04910.60.533470.008476.928012332GAS COCK

22511.04950.60.533470.042356.885666646EFV

2251 1.15.7856666465-6

22511.04910.60.533470.008475.777197508ilL"

22511.04920.60.533470.016945.7602592346-7

22511.049100.60.533470.084695.675567860ilL"

22511.04920.60.533470.016945.6586295857-8

22511.049200.60.533470.169385.489246838"T"

22511.0490.750.60.533470.006355.4828949858-9

890.750.824100.60.265390.053555.429349677liT"

890.750.8240.50.60.265390.002685.4266724119-10

300.50.622100.60.116950.031335.395346390liT"

300.50.62220.60.116950.006275.38908118610-11

270.50.622100.60.116950.025375.363707109ilL"

270.50.62210.60.116950.002545.36116970111-12

270.50.62210.60.116950.002545.358632293GAS COCK

270.50.62240.60.116950.010155.34848266213-14

270.50.62210.60.116950.002545.345945255ilL"

270.50.62210.60.116950.002545.34340784714-15

270.50.62210.60.116950.002545.340870439FLEX CONN.

270.50.62230.6 0.54.840870439

TOT PRESS DROP

PRESS DROP EXCLUDING FLEX CONNECTOR

J. Marx Ayres, P.E.

2.15913

1.65913

Page 2 - 9


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Low-Pressure EFVs

Table 2 - 3

Pressure-Drop Calculations WithUMAC Quake Breaker At Meter And At Each Appliance

Calculations


ININFT INWCINWC1-2

22511.04910.60.533470.008476.991530863"T"

22511.0490.750.60.533470.006356.9851790102-3

22511.04910.60.533470.008476.976709872ilL"

22511.04920.60.533470.016946.9597715983-4

22511.04910.60.533470.008476.951302460GAS COCK

22511.04950.60.533470.042356.908956773EFV

2251 1.15.8089567735-6

22511.04910.60.533470.008475.800487636ilL"

22511.04920.60.533470.016945.7835493616-7

22511.049100.60.533470.084695.698857988ilL"

22511.04920.60.533470.016945.6819197137-8

22511.049200.60.533470.169385.512536966liT"

22511.0490.750.60.533470.006355.5061851138-9

890.750.824100.60.265390.05355·5.452639804"T"

890.750.8240.50.60.265390.002685.4499625399-10

300.50.622100.60.116950.031335.418636518liT"

300.50.62220.60.116950.006275.41237131410-11

270.50.622100.60.116950.025375.386997237ilL"

270.50.62210.60.116950.002545.38445982911-12

270.50.62210.60.116950.002545.381922421GAS COCK

270.50.62240.60.116950.010155.371772790EFV

27 0.35.07177279013-14

270.50.62210.60.116950.002545.069235383ilL"

270.50.62210.60.116950.002545.06669797514-15

270.50.62210.60.116950.002545.064160567FLEX CONN.

270.50.62230.6 0.54.564160567

TOT PRESS DROP


J. Marx Ayres, P.E.

2.43584

1.93584

Page 2 -11


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Low-Pressure EFVs

Table 2 - 4

Pressure-Drop Calculations WithSanders At Meter

Calculations

SECT Qd NOMINALdACTUALLSKhRES PRESSCFH

ININFT INWCINWC1-2

22511.04910.60.533470.008476.991530863liT"

22511.0490.750.60.533470.006356.9851790102-3

22511.04910.60.533470.008476.976709872ilL"

22511.04920.60.533470.016946.9597715983-4

22511.04910.60.533470.008476.951302460GAS COCK

22511.04950.60.533470.042356.908956773EFV

2251 0.56.4089567735-6

22511.04910.60.533470.008476.400487636ilL"

22511.04920.60.533470.016946.3835493616-7

22511.049100.60.533470.084696.298857988ilL"

22511.04920.60.533470.016946.2819197137-8

22511.049200.60.533470.169386.112536966"T"

22511.0490.750.60.533470.006356.1061851138-9

890.750.824100.60.265390.05355.6.052639804"T"

890.750.8240.50.60.265390.002686.0499625399-10

300.50.622100.60.116950.031336.018636518liT"

300.50.62220.60.116950.006276.01237131410-11

270.50.622100.60.116950.025375.986997237ilL"

270.50.62210.60.116950.002545.98445982911-12

270.50.62210.60.116950.002545.981922421GAS COCK

270.50.62240.60.116950.010155.97177279013-14

270.50.62210.60.116950.002545.969235383ilL"

270.50.62210.60.116950.002545.96669797514-15

270.50.62210.60.116950.002545.964160567FLEX CONN.

270.50.62230.6 0.55.464160567

TOT PRESS DROP


J. Marx Ayres, P.E.

1.53584

1.03584

Page 2 -13


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Low-Pressure EFVs

Table 2 - 5

Pressure-Drop Calculations WithSanders At Meter

And At Each Appliance

Calculations


ININFT INWCINWC1-2

22511.04910.60.533470.008476.991530863"T"

22511.0490.750.60.533470.006356.9851790102-3

22511.04910.60.533470.008476.976709872ilL"

22511.04920.60.533470.016946.9597715983-4

22511.04910.60.533470.008476.951302460GAS COCK

22511.04950.60.533470.042356.908956773EFV

2251 0.56.4089567735-6

22511.04910.60.533470.008476.400487636ilL"

22511.04920.60.533470.016946.3835493616-7

22511.049100.60.533470.084696.298857988ilL"

22511.04920.60.533470.016946.2819197137-8

22511.049200.60.533470.169386.112536966"T"

22511.0490.750.60.533470.00635. 6.1061851138-9

890.750.824100.60.265390.053556.052639804"T"

890.750.8240.50.60.265390.002686.0499625399-10

300.50.622100.60.116950.031336.018636518liT"

300.50.62220.60.116950.006276.01237131410-11

270.50.622100.60.116950.025375.986997237ilL"

270.50.62210.60.116950.002545.98445982911-12

270.50.62210.60.116950.002545.981922421GAS COCK

270.50.62240.60.116950.010155.971772790EFV

27 0.55.47177279013-14

270.50.62210.60.116950.002545.469235383"L"

270.50.62210.60.116950.002545.46669797514-15

270.50.62210.60.116950.002545.464160567FLEX CONN.

270.50.62230.6 0.54.964160567

TOT PRESS DROP


J. Marx Ayres, P.E.

2.03584

1.53584

Page 2 -15


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Low-Pressure EFVs

Table 2 - 6

Calculations

Pressure-Drop Calculations WithUMAC Quake Breaker At Meter And Magne-Flo At Each Appliance


ININFT INWCINWC1-2

22511.04910.60.533470.008476.991530863liT"

22511.0490.750.60.533470.006356.9851790102-3

22511.04910.60.533470.008476.976709872ilL"

22511.04920.60.533470.016946.9597715983-4

22511.04910.60.533470.008476.951302460GAS COCK

22511.04950.60.533470.042356.908956773EFV

2251 1.15.8089567735-6

22511.04910.60.533470.008475.800487636ilL"

22511.04920.60.533470.016945.7835493616-7

22511.049100.60.533470.084695.698857988ilL"

22511.04920.60.533470.016945.6819197137-8

22511.049200.60.533470.169385.512536966"T"

22511.0490.750.60.533470.006355.5061851138-9

890.750.824100.60.265390.05355. 5.452639804"T"

890.750.8240.50.60.265390.002685.4499625399-10

300.50.622100.60.116950.031335.418636518"T"

300.50.62220.60.116950.006275.41237131410-11

270.50.622100.60.116950.025375.386997237ilL"

270.50.62210.60.116950.002545.38445982911-12

270.50.62210.60.116950.002545.381922421

GAS COCK

270.50.62240.60.116950.010155.371772790

I::FV(1)

27 0.624.75177279013-14

270.50.62210.60.116950.002544.749235383ilL"

270.50.62210.60.116950.002544.746697975

14-15270.50.62210.60.116950.002544.744160567

FLEX CONN.

270.50.62230.6 0.54.244160567

TOT PRESS DROP


Notes:

(1) Pressure-drop calculation for Magne-Flo 5/8" valveGiven 1" WC @ 70CFH (Table 2 - 1)Ratio: Q=(hY.5h@27 CFH: 70/27=(1)A.5/(h)A.5

=O.62106"WC

J. Marx Ayres, P.E.

2.75584

2.25584

Page 2 -17

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Low-Pressure EFVs

Table 2 - 7

Pressure-Drop Calculations WithSanders At Meter And Magne-Flo At Each Appliance

Calculations


ININFT INWCINWC1-2

22511.04910.60.533470.008476.991530863liT"

22511.0490.750.60.533470.006356.9851790102-3

22511.04910.60.533470.008476.976709872ilL"

22511.04920.60.533470.016946.9597715983-4

22511.04910.60.533470.008476.951302460GAS COCK

22511.04950.60.533470.042356.908956773

FV(SANDERS

2251 0.56.4089567735-6

22511.04910.60.533470.008476.400487636ilL"

22511.04920.60.533470.016946.3835493616-7

22511.049100.60.533470.084696.298857988ilL"

22511.04920.60.533470.016946.2819197137-8

22511.049200.60.533470.169386.112536966"T"

22511.0490.750.60.533470.006356.1061851138-9

890.750.824100.60.265390.053556.052639804liT"

890.750.8240.50.60.265390.002686.0499625399-10

300.50.622100.60.116950.031336.018636518liT"

300.50.62220.60.116950.006276.01237131410-11

270.50.622100.60.116950.025375.986997237ilL"

270.50.62210.60.116950.002545.98445982911-12

270.50.62210.60.116950.002545.981922421GAS COCK

270.50.62240.60.116950.010155.971772790

EFV (1)

27 0.625.35177279013-14

270.50.62210.60.116950.002545.349235383ilL"

270.50.62210.60.116950.002545.346697975

14-15

270.50.62210.60.116950.002545.344160567

FLEX CONN.

270.50.62230.6 0.54.844160567

TOT PRESS DROP


Notes:

(1) Pressure-drop calculation for Magne-Flo 5/8" valveGiven: 1" WC @ 70 CFH (Table 2 - 1)Ratio: Q=(hy.5h@ 27 CFH: 70/27=(1 )A.5(h)A.5

= 0.62106 "wc

J. Marx Ayres, P.E.

2.15584

1.65584

Page 2 -19

Fig

ure

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Low-Pressure EFVs

Table 2 - 8

Pressure-Drop Calculations Without EFVs

Calculations


ININFT INWCINWC1-2

22511.04910.60.533470.008476.991530863GAS COCK

22511.04950.60.533470.042356.9491851763-4

22511.04910.60.533470.008476.940716038ilL"

22511.04920.60.533470.016946.9237777644-5

22511.049100.60.533470.084696.839086390"L"

22511.04920.60.533470.016946.8221481155-6

22511.049200.60.533470.169386.652765368"T"

22511.0490.750.60.533470.006356.6464135156-7

890.750.824100.60.265390.053556.592868207"T"

890.750.8240.50.60.265390.002686.5901909417-8

300.50.622100.60.116950.031336.558864920"T"

300.50.62220.60.116950.006276.5525997168-9

270.50.622100.60.116950.025376.527225639ilL"

270.50.62210.60.116950.002546.5246882319-10

270.50.62210.60.116950.002546.522150824GAS COCK

270.50.62240.60.116950.010156.51200119311-12

270.50.62210.60.116950.002546.509463785ilL"

270.50.62210.60.116950.002546.50692637712-13

270.50.62210.60.116950.002546.504388970t-Lt:)\,. L;VI\lN.

L,fU.::>U.t5LL.~0.6 0.56.IVI

u_vvlKVI-' U.~~::>t51


J. Marx Ayres, P.E.

0.49561

Page 2 - 21

Calculations

/V"k

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Page 2 - 22

Low-Pressure EFVs

J. Marx Ayres, P.E.

Low-Pressure EFVs

3.1 CSA U.S.

Section 3Discussion

Discussion

a. The CSA U.S. Requirements No. 3-92 are for EFVs that are designed to limit theflow of gas in the event that the flow through the valve exceeds the levelspecified by the manufacturer. The criteria are for valves with nominal sizes of 2"or smaller, maximum operating pressures of 250 psi or less, and capability ofoperating in 32° to 125°F environments. The test requirements include the sizeof by-pass area in automatic reset type valves to allow for equalization ofpressures. The closing flow rates are based on 0.64-SG, 1000-BTU/CF gas.The performance requirements include specified operational positions of thevalve, maximum operating pressures, leakage rates not to exceed 20 CC/Hr at1-1/2 times the maximum operating pressure, 10 CFH maximum bypass rate,and operation to reduce the flow of gas through the device to no more than itsbypass flow rate (which must be no more than 2 CFH for manual reset typeEFVs, and no more than 10 CFH for automatic reset type EFVs) whenever theflow reaches that particular device's closing flow rate, which can be anythingbetween 80% and 110%, inclusive, of the manufacturer's specified closing flowrate for that model.

b. The procurement of the CSA test results and other manufacturer literature wasdifficult. The latest UMAC and Sanders data were obtained from attachments to

the Los Angeles Mechanical Testing Laboratory's Research Reports, and theMagne-Flo data from submissions to the DSA.

3.2 Appliance Connectors

3.3

a.

b.

CSA U.S. test data for appliance connectors were not available, and publicationsfrom one manufacturer provided CSA pressure-drop data for straight flexiblemetal tubing without bends that normally occur in the field. See Appendix A. Thepublished data provided flow capacities at 0.5" WC pressure-drop with 0.64-SG,1000/BTU/CF gas per ANSI Z 21.24 CGA 6.10 for 3/8",1/2", and 5/8" nominal0.0. connectors. The UPC Table 12-10 provides capacities of "listed" applianceconnectors in 8" WC or less systems based on 0.2" WC pressure drop with 1100BTU/CF gas. Note 3 under UPC Table 12-10 states that tests were based oncomplete assemblies, including fittings and valves. The test configuration,definition of valve type, and test data were not available to the author, so all ofthe spread sheet calculations incorporated 0.5" WC pressure drop for theappliance connectors.

It should be noted that Brass Craft has recently purchased Magne-Flo and plansto offer the EFVs with their flexible connectors. If this is true, their connector andEFV should be tested and listed as a unit.

Pressure Drops

J. Marx Ayres, P.E. Page 3-1

Low-Pressure EFVs Discussion

The objective of this study was to determine the impact of EFVs on the upe0.5" we maximum piping system pressure-drop allowance. Examination ofTables 2-2 through 2-8 and Figures 2-2 through 2-11 allows the reader to identifythe various pressure drops, starting with a 7" we service. It should be noted thatminimum pressures necessary for safe and efficient appliance operation can varyfrom 5" to 3-1/2" we. It is known that the designer can in some circumstancesuse larger size pipe to off-set the EFV pressure losses, but it is not practical dueto the additional construction costs.


Low-Pressure EFVs

Section 4Conclusions & Recommendations

4.1 Conclusions

Conclusions

1. When EFVs are installed in typically sized low-pressure gas systems, the totalpressure drop of the systems will exceed the UPC maximum allowed 0.5" WCpressure drop.

4.2 Recommendations

1. Building Codes should require mechanical plan checks for any low-pressure gassystems using one or more EFVs.

2. Pressure drops across flexible appliance connectors should be listed with adefined number and radii of bends or loops.

3. If a flexible connector is provided with an EFV, the pressure drops should belisted both with and without the EFV.

J. Marx Ayres, P.E. Page 4-1

low-pressure excess flow natural gas valves, uniform ... · 2.2 spitzglass formula the design of...

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