joint gt-imog/tfg meeting, automated field calibration ... · background •definition of...
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Name:
Date:
Joint GT-IMOG/TFG Meeting,
Automated Field Calibration
Moisture Standard
Russell L. Hallman, Jr. PhD
Consolidated Nuclear Security, LLC
Senior Technical Staff II (Engineer)
9203-F-0009
Background
• Definition of calibration – “To check, adjust, or standardize a measuring
instrument, usually by comparing it with an accepted model.”1
• Moisture monitors throughout Y-12 must be calibrated, often quarterly, requiring
a source of process gas containing a precise amount of moisture spanning the
desired range of concentrations. Gas suppliers CAN NOT provide gases with a
precise amount of moisture because moisture is not a gas but a vapor that
interacts with the surfaces of pipes and containers causing unpredictable swings
in concentrations.
• Low concentrations of moisture in gases must be made when and where they
are going to be used, thus the need for a moisture blending system.
1) The American Heritage® Science Dictionary
Background
• Y-12 currently uses field calibration moisture standards we developed and
patented 2001 which are now inefficient and quickly becoming obsolete.
• Manually operated with moisture set points inferred from a temperature profile (not user
friendly)
• Each instrument has unique moisture-to-temperature correlation
• Limited number of calibration set points
• Embedded controllers are obsolete with vendor support for repairs only
• No data logging capability of the moisture monitor’s performance during testing
• Requires craftsmen presence throughout the workday to manually record the data
• For some sensors changes in moisture level require hours to equilibrate
• Operating pressure and flow ranges are 0-10 psig and100 cc/min which is insufficient
for some new monitors
• Original moisture range 0-10 PPMv
• 2nd modification raised moisture levels to 0-30 PPMv
• 3rd modification 0-100 PPMv
• 4th modification 0-300 PPMv
• Additional configurations for unique instrument calibrations
Objective
• To build an automated moisture blending system for field calibration of
hygrometers with the following attributes:
• Compact and portable
• Operable in a manual or programmatic mode
• Moisture bypass for quick dry down
• Multiple ranges (e.g. 0-10, 0-500, 0-2000 PPMv)
• Increased maximum operating pressure (e.g. 20 psi)
• Higher flow rate of blended gas (e.g. 1500 cc/min)
• Graphical user interface allowing the craftsmen to select
• Moisture content in units of choice (e.g. dew point, frost point, R.H., PPMv, ...)
• Moisture content testing profile (e.g. single setpoint, stair step, ramp and soak, …)
• Data acquisition from instrument being calibrated (e.g. USB, serial port, 1-10v, 4-20ma, …)
• Real-time data analysis of moisture monitor being calibrated (pass/fail, response time, accuracy,
stability, repeatability, …)
• Storage of test results
• Graphical display of testing parameters and moisture monitor performance
Accomplishments
• Accomplishments this FY
• Compact and portable
• To date we have constructed sub-systems of the overall system for development, testing, and
evaluation. The goal is to minimize the footprint while increasing performance. Final assembly
remains.
• Multiple operational modes have been devised with significant improvements to
performance.
• Mode 1) Moisture content controlled by temperature of permeation cell – Pros and Cons,
conservation of dry gas but slower system equilibration to set point change (30 minutes – 1 hour)
• Mode 2) Moisture content controlled by gas blending – Pros and Cons, very fast response rate to
set point change (seconds to minutes) but higher gas usage
• System operations
• Currently control is by PLC and manual flow control – ultimately all control will be by
touchscreen
• System operating pressure raised to 20 psi – no significant effect on moisture content
• System routinely operated higher flow rates of 1500 cc/min – promotes quicker equilibration of
detectors being evaluated
• Single-film permeation cell replaced by multi-film permeation cell for expanded moisture ranges –
films may be changed to meet performance expectations
Accomplishments
• Accomplishments this FY - continued
• Modifications discovered during development
• Polymer film chosen over polymer tube due to morphology of film effecting permeation
• Modified balance pressure manifold for more precise dry gas flow control
• Graphical user interface features
• Unit selection still under development
• Test profiles fully functional (single set point, stair step, and ramp and soak)
• Data acquisition and storage completed for RH Systems LX373, Edgetech DewMaster, Spectra
Sensor TDL
• Plans for the future• Integration of all system control for PLC and touch screen operation
• Test profile development based in other units (ppm, RH, absolute humidity)
• Data acquisition and storage remaining for Ametek 303B and 3050AM
• Statistical analysis for test unit pass/fail determination
• System evaluation and testing by Y-12 Metrology personnel
Permeation cell
Touchscreen User Interface
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Moisture profile
Moisture profile
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Moisture content as a function of flow and temperature
Testing of Ametek 3050AM and Edgetech DewMaster
Demonstration of Control Over Expanded Range
Low Moisture Range Control
Rapid Step Change with Quick Settling
Questions