Positive-displacement flowmeter measures low gas-flow rates by gaging the time required for a slug of mercury to pass between two reference levels in a tube of known volume

Wells, F. E.

English

NASA Technical Reports Server

0 Gas In 
February 1966
	 Brief 66-10036 
NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U. S. space 
program and to encourage their commercial application. Copies are available to the public from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Flowmeter Measures Low Gas-Flow Rates 
Equilibrium Chamber 
The problem: 
To design a meter that will measure low gas-flow 
rates (0.015 to 0.5 cu in./min at standard pressure 
and temperature). 
The solution: 
A positive-displacement flowmeter that measures 
the time required for a slug of mercury to pass be-
tween two reference levels in a tube of known volume.
How it's done: 
The gas admitted to the inlet tube flows in a con-
tinuous path through the equilibrium chamber, the 
metering tube, and the outlet connection. 
In making a measurement, the mercury metering 
dispenser is opened to introduce a precise amount 
of mercury into the equilibrium chamber. The slug 
of mercury (approximately twice as long as the inside 
diameter of the metering tube) will be pushed along 
(continued overleal) 
This document was prepared under the sponsorship of the National 	 Government assumes any liability resulting from the use of the 
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	 will be free from privately owned rights.
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by the gas flow through the metering tube until it 
reaches the mercury separator, at which point it re-
turns to the mercury reservoir for reuse. The gas flow 
leaves the meter through the outlet tube. 
The gas flow rate is calculated by dividing the known 
volume of the metering tube between the lower and 
upper photocell reference levels by the time required 
for the slug of mercury to pass between the two light 
beams intercepted by the photocells. 
Notes: 
I. This laboratory flowmeter can be used for direct 
measurement of low gas-flow rates and as a sec-
ondary standard for calibrating other types of flow-
meters.
2. A related invention is described in NASA Tech 
Brief 65-10137, May 1965. Inquiries may also be 
directed to: 
Technology Utilization Officer 
Marshall Space Flight Center 
Huntsville, Alabama, 35812 
Reference: B66-10036 
Patent statub 
Inquiries about obtaining rights for the commer-
cial use of this invention may be made to NASA, Code 
AGP, Washington, D.C., 20546. 
Source: Frederick E. Wells 
(M-FS-2 15) 
Brief 66-10036	 Category 01


Flowmeter measures low gas-flow rates

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