Closed loop system for a liquid nitrogen high pressure pump feeds back gaseous nitrogen generated by heat leak into the reservoir to maintain the pressure in the storage tank. This safer, more efficient system eliminates the need for auxiliary gas to maintain the tank pressure and can be used on relatively high cryogenic pumping systems

Landy, D. G.

English

NASA Technical Reports Server

September 1966	 Brief 66-10408 
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. 
Closed Loop Operation Eliminates Need for 
Auxiliary Gas in High Pressure Pumping Station 
Jacket Return 
Vent	 Pressure	 igh Pressure Bypass 
High Pressure LN2 (5000 PSI) 
D
Closed L op 
Loop 
—32001 
Heat ^+700 F 
LN2	 Pump	 Exchanger
(5000 PSI) 
The problem: 
The liquid nitrogen high pressure pump requires 
a continual bleed to maintain the liquid nitrogen level 
in the suction reservoir and coolant jacket. In an open 
loop system the bleed valve is vented to the atmos-
phere and a separate gaseous nitrogen source is pro-
vided to maintain the tank pressure of the liquid 
nitrogen. The open loop system requires continuous 
operator attendance to prevent burnout, extensive 
temperature rise in the heat exchanger, and possible 
explosion. 
The solution: 
A closed loop system in which the gaseous nitro-
gen generated in the pump and in the liquid nitrogen 
pipeline, due to heat leak, is fed back into the 
reservoir to maintain the pressure in the liquid nitro-
gen storage tank. 
How it's done: 
The bleed lines from the pump and jacket return
are connected to the top of the LN 2 storage tank. The 
nitrogen gas that is generated by the pump and by 
the heat leak in the LN 2 pipeline is then utilized to 
maintain the pressure in the storage tank. The gas 
is no longer vented to the atmosphere, eliminating 
the requirement for auxiliary gas to maintain the tank 
pressure, making the operation more efficient and 
safer. 
Notes: 
1. The closed loop method has been successfully 
applied to a relatively high (15 gpm) cryogenic 
pumping system. 
2. Inquiries concerning this invention may be di-
rected to: 
Technology Utilization Officer 
Marshall Space Flight Center 
Huntsville, Alabama 35812 
Reference: B66-10408
(continued ovcrleaf) 
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.
https://ntrs.nasa.gov/search.jsp?R=19660000407 2020-03-11T17:35:33+00:00Z
Patent status: 
Inquiries about obtaining rights for the commercial 
use of the invention may be made to NASA, Code 
GP, Washington, D.C. 20546.
Source: D. G. Landy
of North American Aviation, Inc. 
under contract to
Marshall Space Flight Center 
(M-FS-893) 
Brief 66-10408 °	 Category 05


Closed loop operation eliminates need for auxiliary gas in high pressure pumping station

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