Valve leakage due to contaminant entrapment and chattering is effectively minimized by a metallic poppet-and-seat check valve designed for use in extreme environmental and fluid temperature conditions

Whitten, D. E.

English

NASA Technical Reports Server

December 1970	 Brief 70-10688 
NASA TECH BRIEF 
JJMW
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nology Utilization Division, NASA, Code UT, Washington, D.C. 20546. 
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Low Leak Rate Poppet-and-Seat Check Valve 
Valve leakage due to contaminant entrapment and 
chattering has been effectively minimized by a metal-
lic poppet-and-seat check valve designed for use in 
extreme environmental and fluid temperature condi-
tions. Operation under these conditions normally 
requires that the opening distance of the valve be very 
small. Under certain resonant conditions, this mode 
of operation may cause the valve to chatter, which 
Diaphragm Stop 
Secondary \Finger Spring
	
Seat	
____
Valve Poppet 
Orifice Seat
	
Orifice	 I 
	
Poppet	 Primary 
Seat 
Longitudinal Section of Valve 
in turn causes erratic operation of the valve and ex-
cessive wear on the valve sealing surfaces. The small 
opening distance also contributes to contaminants 
being trapped between the sealing surfaces, pre-
venting the valve from closing completely. Both 
characteristics contribute to valve leakage which may 
be unacceptable for the particular application.
Two design features of the poppet-and-seat check 
valve (see fig.) eliminate these problems. First, 
contaminant entrapment problems are minimized by 
the double seat and poppet configuration which per-
mits an opening arrangement that can tolerate con-
tamination of a certain particle size without de-
gradation of the valve sealing capability. The 
arrangement consists of the primary sealing point 
between the fixed orifice seat and the valve poppet, 
and the secondary sealing point between the orifice 
poppet and the valve poppet. Upstream of the 
valve orifice is a flexible convoluted metal diaphragm 
attached to the orifice poppet. This feature permits 
movement of the secondary seat and acts as a seal 
to prevent gas flow except ithrough the central hole 
in the secondary seat.
	 - 
Second, downstream of the valve orifice is the 
finger spring which exerts a force against the valve 
poppet, tending to keep the valve in a closed 
position. This finger spring is used to minimize 
chatter. It has a low mass and a natural fre-
quency above the range which causes chatter of the 
poppet. Should chatter occur, the double seat con-
figuration makes it possible for all excessive wear 
to take place on one sealing interface with little wear 
or damage to the other sealing interface. 
Note: 
Requests for further information may be directed 
to:
Technology Utilization Officer 
Manned Spacecraft Center, Code BM7 
Houston, Texas 77058 
Reference: TSP70-10688
contriiiied Os crle.iI 
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=19700000665 2020-03-17T01:03:34+00:00Z
Patent status: 
Inquiries about obtaining rights for the commercial 
use of this invention may be made to: 
Patent Counsel 
Mail Code AM 
Manned Spacecraft Center 
Houston, Texas 77058 
Source: David E. Whitten of

Bendix Corp.

under contract to

Manned Spacecraft Center

(MSC-13587)
is 
Brief 70-10688	
Category 07


Low leak rate poppet-and-seat check valve

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