Insulated feed-thru conduit minimizes heat pickup by a cryogenic fluid passing through the walls of a double high-vacuum chamber, and is capable of expansion and contraction with the walls of the chamber. It uses a bellows and rigid cylinder to provide a low-loss feed-thru for the cryogenic liquid

Yager, S. P.

English

NASA Technical Reports Server

December 1967	 Brief 67-10619 
NASA TECH BRIEF• 
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. 
Feed-Thru Conduit Minimizes Heat Pickup 
Wall	 Metal	 Wall 
\	 Bellows	 Conduit 
/ Z , Conduit	
Weld / Cylindrical 
i  
Cavity 
Vent Flange Rigid Cylinder	
Copper Alloy Seal 
The problem: 
To design an insulated feed-thru conduit which will 
minimize heat pickup by a cryogenic fluid passing 
through the walls of a double high-vacuum chamber. 
The feed-thru conduit must also be capable of expan-
sion and contraction with the walls of the chamber. 
Previous systems had curved conduit interconnections 
between the tank walls to allow for expansion, but 
excessive heat pickup resulted from conduction 
around the conduit. 
The solution: 
A straight through conduit utilizing a bellows and 
rigid cylinder to provide a low loss feed-thru for 
cryogenic liquid passing into a high vacuum chamber. 
How it's done: 
The straight through conduit has a bellows for 
linear expansion and contraction within the walls of 
the vacuum chamber. One end of the bellows is con-
nected to one wall; the other is sealed and clamped 
to the conduit. Thus, a cold chamber surrounds about
one-half the length of the conduit. A rigid cylinder 
surrounds the other half of the conduit, thermally 
isolating it from the wall by means of the long thermal 
conductive path from the wall to the connection on 
the conduit. The rigid cylinder is welded to the con-
duit close to the bellows and conduit seal. A cylin-
drical cavity under the outer shell of the conduit 
provides additional insulation. This is vented to the 
guard vacuum between the two walls. 
Notes: 
I. The feed-thru system was designed to feed liquid 
helium into a cryopump and it is applicable to high 
vacuum systems and to the storage of all cryogens. 
2. Inquiries concerning this invention may be directed 
to:
Technology Utilization Officer 
NASA Pasadena Office 
4800 Oak Grove Drive 
Pasadena, California 91103 
Reference: B67-10619 (continued overleaf( 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19670000618 2020-03-11T21:35:37+00:00Z
Patent status:	 - 
Inquiries about obtaining rights for the commercial 
use of this invention may be made to NASA, Code 
GP, Washington, D.C. 20546.
Source: S. P. Yager 
Jet Propulsion Laboratory

(J PL-847) 
Brief 67-10619	 Category 05


Feed-thru conduit minimizes heat pickup

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