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Test Stand Accessories | Up
Aircrew Survival Equipmentman 1 & C - Aviation theories and other practices | Next
Bell Jar Leakage |
this gage consistently reads low, you probably
have leaky fittings. To correct this problem, you
will need to perform one or two leakage tests.
To perform leakage tests, pressurize the system
and apply a soap solution to the various fittings.
Escaping gas will form soap bubbles, and you can
locate the leaks.
Leakage Test, Accessories Section
To perform the leakage test on the accessories
section of the test stand, proceed as follows:
1. Install nipple assembly 14 (figure 1-5) in
bell jar bottom coupling C-1. Connect one end
of hose 3 (figure 1-5) to the adapter and the other
end to differential pressure connection NIP-7.
2. Ensure test-pressure-gage-to-bell-jar valve
V-2 is open. Ensure system bleed valve V-5, test
pressure gage build-up and vent valve V-10, and
differential pressure bleed valve V-7 are closed.
3. Open differential pressure shutoff valve
V-8.
4. Open oxygen supply cylinder valve. Open
oxygen supply valve V-6 until 160 psig is indicated
on test pressure gage PG-1.
5. Close oxygen supply valve V-6. Leakage
will be indicated by a drop in pressure on PG-1.
Leakage must not be more than 2 psig in 10
minutes.
6. Leave all hoses and valves in their present
position.
Leakage Test, Test Stand
To perform the leakage test on the entire test
stand, proceed as follows:
1. Open converter supply flow control valve
V-9 and test pressure gage build-up and flow valve
V-10.
2. Plug converter supply outlet NIP-5 and
supply to converter connection NIP-6. Ensure
system bleed valve V-5 is closed.
3. Open supply valve V-6 until relief valve
V-11 unseats. (Relief valve shall relieve at no more
than 120 psig and be leak-tight at 100 psig.)
Using system bleed valve V-5, decrease pressure
until 100 psig is indicated on test pressure gage
PG-1. Close valve V-6. Leakage will be indicated
by a drop in pressure on PG-1. Leakage shall be
no more than 10 psig in 10 minutes.
4. Bleed the test stand by opening system
bleed valve V-5. Close all test stand valves.
Remove plugs from converter supply outlet NIP-5
and supply to converter connection NIP-6.
PG-1 Pointer Pegs
Anytime the 0-160 psig pressure gage pegs, it
is caused by pressure regulator R-1. This pressure
regulator is set to maintain 160 psig with 1800 psig
supply pressure applied. If the PG-1 pressure gage
pegs, your regulator is delivering pressure above
160 psig and the pressure must be adjusted.
To set oxygen pressure regulator R-1 to
maintain 160 psig with 1800 psig supply pressure
applied, proceed as follows:
CAUTION
Valves V-2, V-5, V-6, V-7, and V-10 are
metering (needle) valves. Overtightening
when closing will damage valve seat. Only
finger-tight pressure should be used when
closing valves.
1. Ensure all test stand valves are closed, and
plug bell jar bottom coupling C-1.
W A R N I NG
When you are working with oxygen, make
certain that clothing, tubing, fittings, and
equipment are free of oil, grease, fuel,
h y d r a u l i c f l u i d , o r a n y c o m b u s t i b le
materials. When oxygen is under pressure,
fire or explosion may result when even
slight traces of combustible materials come
in contact.
2. Open oxygen supply cylinder valve.
N O T E : W h e n s e t t i n g r e g u l a t o r R - 1 , a
minimum of 1800 psig oxygen pressure should be
applied to the regulator.
3. Slowly open test-pressure-gage-to-bell-jar
valve V-2, and fully open oxygen supply valve
V-6.
4. Loosen the hex locknut located on the front
of regulator R-1. Turn the T-handle until 160 psig
registers on test pressure gage PG-1. Tighten the
hex locknut.
5. Close the oxygen supply cylinder valve and
open system bleed valve V-5 to bleed pressure
from system. Remove the plug from bell jar bot-
tom coupling C-1.
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