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(SR-52) a Dynamic Gas-Mixing System
12-21-2019, 11:40 AM
Post: #1
(SR-52) a Dynamic Gas-Mixing System
An extract from a Dynamic Gas-Mixing System, U.S.DoI (BoM), Information Circular 8934 (30 pgs.)

A dynamic gas-mixing system assembled by the Bureau of Mines for the generation of precise gas mixtures from sources of concentrated or pure gases and diluent gases is described …

… This report describes the design and fabrication of a dynamic gas dilution system that satisfies the demands of gas instrument evaluation test methods that require a flowing source of several accurately known gas mixtures…

Figures C-1 and C-2 contain the program for the Texas Instruments SR52 calculator. The program was developed to facilitate operation and calibration of the system and involves corrections of flow rate owing to prevailing temperature and pressures.
The calibration graph for each controller is a plot of the flow rate at our standard temperature and pressure versus the digital panel meter reading as described in the paper. The first function of the program (User Instructions, steps 1A-3A) is used to correct the flow rate obtained from the calibration graph to the prevailing laboratory temperature and pressure.
The second function (User Instructions, steps 1B-3B) is the inverse of the first and is used to convert a flow rate measured under prevailing temperatures and pressures to our standard reference temperature and pressure.
A soap-bubble meter is used to measure the volume flow rate from the controller. The average of 10 bubble transit times is divided by the bubble meter vol\ime. This gives the actual volume flow rate through the controller for that particular setting and indication on the digital panel meter at the prevailing temperature and pressure. The flow rate is then converted to a flow rate at STP to be plotted against the panel meter indication. This procedure is repeated at as many flow controller settings as required to cover the controller range and to produce a calibration graph to the desired accuracy"

The program instructions and listing in Appendix C is a typed PPX-52 document.

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