Inverted tee, installed at a high point in a cryogenic transfer line, is equipped with an insulated bleed line that passes a fixed amount of cryogenic fluid at atmospheric pressure. A sensing device activates a vent valve in the tee stack whenever gaseous nitrogen is present

Lindgren, A. R.

English

NASA Technical Reports Server

October 1967	 Brief 67-10424 
NASA TECH BRIEF	
Cf I 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Temperature-Sensed Cryogenic Bleed Maintains Liquid State in Transfer Line 
To Vent Valve
Bleed Line
Insulation 
Needle Valve 
Evacuated Annulus—i  
The problem: 
To maintain nitrogen in the liquid state constantly 
in a cryogenic transfer line. 
The solution: 
An inverted tee installed at a high point in the 
transfer line is equipped with an insulated bleed line 
that constantly passes a fixed amount of the cryogenic 
fluid at atmospheric pressure, over a sensing device. 
The sensing device actuates a vent valve in the tee 
stack whenever gaseous nitrogen is present. 
Notes: 
I. This system has an advantage over that employing 
a sensor within the transfer line since the latter 
would react to differences in line pressure as well 
as to gaseous versus liquid phases. The temperature 
of LN2 varies between —3201 F at atmospheric 
pressure and —274° F at 140 psia.
2. Inquiries concerning this innovation may be di-
rected to:
Technology Utilization Officer 
Marshall Space Flight Center 
Huntsville, Alabama 35812 
Reference: B67-10424 
Patent status: 
No patent action is contemplated by NASA. 
Source: A. R. Lindgren 
of North American Aviation, Inc. 
under contract to 
Marshall Space Flight Center 
(MFS-12681) 
Category 01 
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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Temperature-sensed cryogenic bleed maintains liquid state in transfer line

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