To prevent fluid leakage around piston seals separating two fluids under differential pressure, a venting system has been devised. Two methods may be used for venting seals through internal passages to an external low-pressure area, O-ring or split-ring seals

Mac Glashan, W. F.

Morrison, R.

English

NASA Technical Reports Server

FIGURE 2 
December 1964	 Brief 63-10141 
NASA TECH BRIEF 
This NASA Tech Brief is issued by the Technology Utilization Division to acquaint 
industry with the technical content of an innovation derived from the space program. 
Vented Piston Seal Prevents Fluid Leakage Between Two Chambers 
Cylinder Wall -. 
Fluid Chamber—_.. 
IEE
t
Piston 
ing Seals - 
rential Groove 
Radial Vent 
Fluid Chamber' 
Axial Vent to 
Low-Pressure Area 
FIGURE 1
The problem: Prevention of fluid leakage around 
piston seals separating two fluids under pressure dif-
ferentials of up to 100 psi. 
The solution: A venting system is provided between 
two annular sealing surfaces on the piston separating 
one fluid from another under different pressure. 
How it's done: Two design variations are shown 
in cross section. 
In one design (Figure 1), two conventional 0-ring 
seals are recessed into the surface of the piston. 
Between the 0-rings is an external annular groove 
which has a number of small radial vent holes leading 
to an axial vent. Fluid leaking past either of the 0-ring
seals will flow through the internal passages to the 
atmosphere or other external low-pressure area. 
In the alternative design (Figure 2), the piston is 
thinner because a single split-ring seal is recessed in 
the surface of the piston. As in the first design, leakage 
of fluid around the seal will be vented through the 
internal passages to an external low-pressure area. 
Notes: 
I. The vented piston seal may be used on compressors, 
piston pumps, and valves to prevent contamination 
of a fluid in one chamber with a fluid in a second 
chamber.
(continued overleaf) 
-.
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States Govern-
ment, nor NASA, nor any person acting on behalf of NASA: A. Makes 
any warranty, or representation, express or implied, with respect to the 
accuracy, completeness, or usefulness of the information contained in
this document, or that the use of any information, apparatus, method, 
or process disclosed in this document may not infringe privately-owned 
rights; or B. Assumes any liabilities with respect to the use of, or for 
damages resulting from the use of, any information, apparatus, method, 
or process disclosed in this document.
https://ntrs.nasa.gov/search.jsp?R=19630000015 2020-03-11T16:44:59+00:00Z
2. Inquiries concerning this innovation may be	 Patent status: NASA encourages commercial use 
directed to:	 of this innovation. No patent action is contemplated. 
Technology Utilization Officer Source: William F. MacGlashan and 
Jet Propulsion Laboratory	 Robert Morrison
4800 Oak Grove Drive 
Pasadena, California, 91103 	
(JPL-179)
Reference: B63-10141 
Brief 63-10141	 Category No. 05


Vented piston seal prevents fluid leakage between two chambers

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