System of short length U-tube manometers with a proportionally divided reference pressure measures high fluid pressures

Sather, B. I.

English

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March 1965	 Brief 65-10027 
S	 NASA TECH BRIEF 
_& 
NASA Tech Briefs are issued by the Technology Utilization Division to summarize specific 
technical innovations derived from the space program. Copies are available to the public from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia, 22151. 
Fluid-Pressure Measurement Apparatus Uses Short-Length Manometer Tubes 
Pressure Reference Source 
Pej 
Pressures To Be Measured 
A I B I C I	 I
	 2/3 Pll.^ 
PRW
	
Pp 
Selection	 II 
Valves	 II
Kendall Boosters 
Pr 
Atmospheric
Pressure 
/3P5	 4 
Common Well 
Manometer 
A: Selection Valve Open 
B. C. 0: Selection Valves Closed 
The problem: Measuring high fluid pressures by 
means of manometers. In situations where high pres-
sures occur, an inordinately long column of liquid and 
tube would be required in a conventional manometer. 
Liquid blowout could also occur from the open end of 
such a manometer during pressure surges. 
The solution: Use of a system of short-length U-
tube manometers in conjunction with a reference pres-
sure which is divided into proportional parts.
How it's done: A reference pressure P R divided 
into proportions by (Kendall) ratio boosters is intro-
duced into a U-tube system. The illustration shows 
three separate U-tubes, with the indicated proportions 
of the reference pressure applied to the different 
branches. With this proportioning of the pressures, 
the difference in the heights, h 1, h 2, and h 3, of the 
liquid levels in each U-tube is approximately the same 
(h1h2h31/3 ER)' and the reference pressure can 
therefore be determined by arithmetically adding the 
(continued overleaf) 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States Govern-
ment, nor NASA, nor any person acting on behalf of NASA: A. Makes 
any warranty or representation, express or implied, with respect to the 
accuracy, completeness, or usefulness of the information contained in
this document, or that the use of any information, apparatus, method, 
or process disclosed in this document may not infringe privately-owned 
rights; or B. Assumes any liabilities with respect to the use of, or for 
damages resulting from the use of, any information, apparatus, method, 
or process disclosed in this document.
https://ntrs.nasa.gov/search.jsp?R=19650000027 2020-03-11T17:17:29+00:00Z
three level differentials. The reference pressure is also 
introduced into one branch of a common-well ma-
nometer, and the pressure to be measured, 
applied to another branch of the common-well ma-
nometer. It is easy to show that for this configuration, 
PX = P R+ H , or PrH+h i +h 2+h 3, where H is the 
difference in the heights of the liuid levels in the two 
branches of the manometer in the common well. Since 
the last branch of the U-tube is open to the atmos-
phere, Px is the gage pressure (in terms of the height 
of the liquid used in the manometer system).
Notes: 
1. The reference pressure may be supplied from any 
convenient source within the pressure system. This 
pressure need not be constant. 
2. Inquiries concerning this innovation may be di-
rected to: 
Technology Utilization Officer 
Lewis Research Center 
21000 Brookpark Road 
Cleveland, Ohio, 44135 
Reference: B65-10027 
Patent status: NASA encourages commercial use 
of this innovation. No patent action is contemplated. 
Source: B.I. Sather

(Lewis-28) 
Brief 65-10027	 Category No. 05


Fluid-pressure measurement apparatus uses short-length manometer tubes

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