Lightweight cryostat made of expanded polystyrene reduces eccentricity in a tensile system being tested under liquid nitrogen. The cryostat is attached directly to the tensile system by a special seal, reducing misalignment effects due to cryostat weight, and facilitates viewing and loading of the specimens

Shogan, R. P.

Skalka, R. J.

English

NASA Technical Reports Server

December 1967
	 Brief 67-10613 
IYES D	 AEC-NASA TECH BRIEF 
AEC-NASA Tech Briefs describe innovations resulting from the research and development program 
of the U.S. AEC or from AEC-NASA interagency efforts. They are issued to encourage commercial 
application. Tech Briefs are published by NASA and may be purchased, at 15 cents each, from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Polystyrene Cryostat Facilitates Testing Tensile Specimens under 
Liquid Nitrogen
Wall Thickness Tapers 
From 1' At Top 
To 2" At Bottom 
Viewing Window 
Pull 
. 
SECTION OF CRYOSTAT 
Grip End 
Clamp 0' Rings
Acrylite 
Layered 
Sealant
Force 
Fit 
Groove For
Washer	 Sealant 
Plug for 
Drainage
Polystyrene
SIDE VIEW OF WINDOW 
Spacer 
r 
Pull Rod
 
I	 I
PULL ROD ASSEMBLY 
The problem: 
In testing irradiated tensile specimens under liquid 
nitrogen, a slight eccentricity in the tensile system 
will cause erroneous results. A conventional metal-
type cryostat not only adds eccentricity to the system 
because of its weight, but also makes it difficult to 
ascertain when a test specimen is properly seated. 
The solution: 
A lightweight cryostat made of expanded polysty-
rene. The lightweight cryostat is attached directly to 
the tensile system by a special seal, reducing mis-
alignment effects due to cryostat weight, and facili-
tates viewing and loading of the specimens.
How it's done: 
The cryostat is made of expanded polystyrene (1 
lb/cu ft density) and is much lighter than the con-
ventional metal cryostats. The light weight allows it 
to be attached directly to the bottom pull rod of the 
tensile testing mechanism without eccentricity prob-
lems and eliminates the need for complicated dynamic 
seals. The material itself is an excellent insulator and 
is nonporous. A thin layer of a room-temperature-
curing silicon adhesive painted on the interior and 
exterior of the cryostat increases the resistance of 
the material to LN2 and keeps moisture out of the 
foam. The low density material is not subject to dam-
aging thermal stresses. Two acrylite windows are 
AIIIIIIIIIIIIIII 	
(continued overleaf) 
This document was prepared under the sponsorship of the Atomic 
Inergy Commission and/or the National Aeronautics and Space 
Administration. Neither the United States Government nor any per-
son 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 the use of any information, apparatus, 
method, or process disclosed in this document may not infringe pri-
vately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19670000612 2020-03-11T21:27:16+00:00Z
2. Inquiries concerning this innovation may be di-
rected to:
Technology Utilization Officer 	
is AEC—NASA Space Nuclear Propulsion 
Office 
U.S. Atomic Energy Commission 
Washington, D.C. 20545
	 - 
Reference: B67-10613 
incorporated in opposite walls of the cryostat, per-
mitting excellent view of the specimen and grips. The 
windows and pull rod assembly are sealed with the 
silicone adhesive; 0-rings are also used in sealing the 
pull rod. The sealant is effective when used sparingly 
or when put on in separate layers. 
Notes: 
I. The system has been filled with LN2 and emptied 
(by removal of a drain plug) many times without 
detrimental effects. Advantages of the cryostat in-
clude: simplicity of design (there are no moving 
seals or complicated assemblies); light weight; 
economy and ease of fabrication (all the materials 
necessary are common, and the polystyrene can be 
easily shaped with a hot wire cutter in the form 
of a loop); economy of LN2 use (because the cryo-
stat is made of an insulating material and because 
the seals are effective, boil-off and leakage losses 
of LN2 are reduced); and ease of adaptability for 
use with other grip assemblies and materials.
Patent status: 
No patent action is contemplated by AEC or 
NASA.
Source: R. P. Shogan and R. J. Skalka

of Westinghouse Astronuclear Laboratory

under contract to

AEC—NASA Space Nuclear Propulsion Office

(N UC- 10522) 
Brief 67-10613	 Category 02


Polystyrene cryostat facilitates testing tensile specimens under liquid nitrogen

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