A levelometer system, in which the level of cryogenic liquid to be controlled affects the level of an electrolyte, automatically switches a pump on and off. A pressure sensitive diaphragm can also throw a microswitch to start or stop the pump

Tener, W. M.

English

NASA Technical Reports Server

Mrch 1964	 Brief 63-10250 
NASA TECH BRIEF 
This NASA Tech Brief is issued by the Technology Utilization Division to acquaint industry 
with the technical content of an innovation derived from the NASA space program. 
Level of Super-Cold Liquids Automatically Maintained by Levelometer 
High Level Electrode Low Level Electrode To High Level Electrode
To Pump 
Switch
To Low Level Electrode
--i\ 
Metering 
Valve
J 
Solenoid
Nitrogen 
Battery Electrolyte 
----------
To Bottom Electrode 
Pump Bottom Electrode
Level to be 
Cryogenic Tank controlled
Nitrogen 
The problem: Maintaining the desired level of a 
liquid at cryogenic temperatures, or of a liquid which 
tends to boil off at normal temperatures. The required 
system must be automatic and dependable so it can 
be left unattended for long periods of time. 
The solution: A levelometer '-system in which the 
level of cryogenic liquid to be controlled affects the 
level of an electrolyte, or of a diaphragm, and auto-
matically switches a pump on or off. 
How it's done: Two tubes lead into a tank contain-
ing the liquid at cryogenic temperature. One comes 
from the pump which operates on demand to pump 
in more fluid, in this case liquid nitrogen. The second 
tube goes well below the surface of the liquid and acts 
as a demand sensor for another vessel containing an 
electrolyte and three electrodes. In the tubing between 
the two vessels there is a metering valve and a gas 
supply container. Gas pressure is set to permit con-
tinuous, moderate bubbling from the submerged end 
of the tubing in the tank.
If the level rises or falls in the cryogenic tank, it can 
be seen that this change in hydraulic pressure will be 
transferred back to the vessel with the electrolyte. 
When the liquid level drops, for example, the electro-
lyte will rise in the enlarged eRd of the tube and cause 
the electrolyte level to drop. 
Lowering of the electrolyte level will uncover the 
shorter of the two top electrodes, actuate the pump 
and liquid will be pumped into the tank. Raising the 
liquid level in the cryogenic tank reverses the action 
causing the longer electrode to be uncovered and stop-
ping the pump. 
Another device can be utilized in place of the elec-
trolyte vessel. A diaphragm can be connected to the 
tubing so that changes in the nitrogen gas pressure 
cause a single throw microswitch to start or stop the 
pump. The diaphragm is attached to a lever pressing 
against the microswitch. Movement of the diaphragm 
will open or close the switch.
(continued overleaf) 
This document was prepared under the sponsorship of the National 	 this document, or that the use of any information, apparatus, method, 
Aeronautics and Space Administration. Neither the United States Govern- 	 or process disclosed in this document may not infringe privately-owned 
ment, nor NASA, nor any person acting on behalf of NASA: A. Makes 	 rights; or B. Assumes any liabilities with respect to the use of, or for 
any warranty or representation, express or implied, with respect to the 	 damages resulting from the use of, any information, apparatus, method, 
accuracy, completeness, or usefulness of the information contained in 	 or process disclosed in this document. 
https://ntrs.nasa.gov/search.jsp?R=19630000035 2020-03-11T16:46:00+00:00Z
Note: 
These devices for keeping a liquid level at a desired 
point would be useful in many manufacturing proc-
esses where a constant amount of fluid must be kept 
in a tank. Chemical plants and others using liquid 
chemicals or solutions could find the levelometer of 
value.
Patent status: NASA encourages commercial use 
of this innovation. No patent action is contemplated. 
Source: Wallis M. Tener 
Jet Propulsion Laboratory (JPL-397) 
Brief 63-10250


Level of super-cold liquids automatically maintained by levelometer

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