Mariotte bottle as liquid displacement device was used to measure gas volumes at flow rates that are far below threshold of wet test gas meters. Study of factors affecting amount of liquid displaced by gas flow was completed, and equations were derived which relate different variables

Christian, J. D.

English

NASA Technical Reports Server

December 1972	 B72-10699 
NASA TECH BRIEF S	 Ames Research Center
	 -4r 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Accurate Measurement of Gas Volumes by Liquid Displacement 
A Mariotte bottle is frequently used to obtain low, 
constant rates of gas or liquid flow, but it is also used 
as a liquid displacement device to measure volumes 
of gas at flow rates that are far below the threshold 
of wet-test gas meters. Flow rates may be determined 
by measuring the time elapsed during collection of a 
quantity of gas. With Mariotte bottles of ordinary 
design, the liquid displacement method provides 
accuracies in the vicinity of 1 to 2 percent; however, 
with proper techniques it is possible to achieve ac-
curacies of about 0.1 percent, but careful attention 
must be given to apparatus design, the relative 
volumes of the metered gas and the confining liquid, 
and other factors such as gas solubilities, the non-
ideal behavior of real gases, constancy of ambient 
temperature, etc. 
Gas nonidealities become significant when accu-
racies better than 1 percent are required; however, 
with most "insoluble" gases such as helium and nitro-
gen or oxygen, departure from ideal behavior will in-
fluence results less than 0.1 percent. For soluble 
gases such as acetylene or carbon dioxide, corrections 
can be appreciable and generally are of the order of 
2.5 percent; for inert gases, with water as the con-
fining liquid, the error will be about 0.02 percent.
A detailed study of the factors affecting the amount 
of liquid (usually water) displaced from a Mariotte 
bottle by a flow of gas has been completed, and equa-
tions have been derived which relate the different 
variables involved. The report which summarizes 
results of the study also includes a discussion of design 
criteria and operating procedures for achieving ac-
curacies of the order 'of 0.01 percent. Of particular 
interest are discussions of the design of Mariotte 
bottles which will provide required levels of accuracy. 
Note: 
Requests for further information may be directed 
to:
Technology Utilization Officer 
Ames Research Center 
Moffett Field, California 94035 
Reference: TSP 72-10699 
Patent status: 
NASA has decided not to apply for a patent. 
Source: Jerry D. Christian

Ames Research Center

(ARC-10723) 
Category 03 
This document was prepared under the sponsorship of the National
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Aeronautics and Space Administration. Neither the United States
	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States
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Accurate measurement of gas volumes by liquid displacement

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