(6)
Note vacuum gage reading when safety relief valve opens. Valve should open between
16.8 and 17.8 in. Hg.
(7)
Set pressure regulator on valve test fixture so that regulator valve is closed.
(8)
Remove valve test fixture from airplane and disconnect air source.
(9)
Repeat test for other safety relief valve.
501
Jun 20/87 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 21-32-21 Page 501
Safety Relief Valve Test 500
21-32-21 Figure 501 Oct 20/92
Page 502
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
3. Test Safety Relief Valve Using Boeing Test Equipment (Fig. 501)
A. Equipment and Materials
(1)
A21010-( ), Vacuum Tank - Safety Relief Valve Test
(2)
Shop Air Source (capable of 60-80 psi)
B. Test Safety Relief Valve
(1)
Connect the air source to the quick-disconnect air connection on the vacuum tank assembly.
(2)
Make sure the vacuum regulator valve is turned fully clockwise.
(3)
Adjust the air control valve until the indication on the pressure gage is 70 +10 psi.
(4)
Make sure that the vacuum head assembly valve is closed.
(5)
Adjust the vacuum regulator valve until the differential pressure is approximately 2.0 psi.
NOTE: Turn the vacuum regulator valve counterclockwise to increase the vacuum (differential pressure). The arrow on the vacuum regulator valve indicates an increase of pressure, not vacuum.
(6)
Put the vacuum head assembly over the safety relief valve and open the vacuum head assembly valve.
CAUTION: HOLD THE VACUUM HEAD ASSEMBLY AGAINST THE AIRPLANE BODY DURING THE TEST. WHEN A VACUUM IS NOT PRESENT, THE VACUUM HEAD ASSEMBLY CAN FALL TO THE GROUND AND DAMAGE CAN OCCUR.
(7)
Adjust the vacuum regulator valve until the safety relief valve opens such that the indication on the vacuum rate gage is not more than 2.4 psi/minute.
NOTE: When the indication on the differential pressure gage stops to increase and then starts to decrease, the safety relief valve has opened.
(8)
Make sure that the safety relief valve opens at a differential pressure of 8.25 to 8.74 psi.
NOTE: After the safety relief valve opens, the differential pressure decreases below 8.25 psi and then starts to increase.
(9)
If the safety relief valve opens at a differential pressure that is too high, make sure that there are no leaks at the tubing connections on the vacuum tank assembly.
(10)
Adjust the vacuum regulator valve to decrease the indication on the differential pressure gage to 2.0 psi.
CAUTION: DO NOT DECREASE THE DIFFERENTIAL PRESSURE AT A RATE GREATER THAN 4.0 PSI/MINUTE AS SHOWN ON THE VACUUM RATE GAGE. DAMAGE TO THE SAFETY RELIEF VALVE CAN OCCUR IF THE DIFFERENTIAL PRESSURE IS DECREASED TOO QUICKLY.
(11)
Close the vacuum head assembly valve.
(12)
Turn the vacuum regulator valve fully clockwise to decrease the differential pressure to zero psi.
(13)
Close the air control valve.
(14)
Remove the test equipment from the airplane.
(15)
Do the test again for the other safety relief valve.
500
May 01/99 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 21-32-21 Page 503
500
21-32-21 Page 504 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. Oct 20/92
SAFETY RELIEF VALVE FILTER - REMOVAL/INSTALLATION
1. General
A. The safety relief valve filter is a throw-away type filter which prevents contamination of relief valve control chamber from passenger cabin exhaust air.
2. Remove Safety Relief Valve Filter (Fig. 401)
A. Remove right panel of aft cargo compartment aft bulkhead.
B. Press down on filter cover, rotate cover counterclockwise and remove cover.
C. Remove filter and packing.
3. Install Safety Relief Valve Filter
A. Check condition of filter cavity and clean if necessary.
(1) If necessary, clean filter cavity with soft, lint-free cloth moistened with trichloroethylene then wipe dry with clean lint-free cloth.
CAUTION: DO NOT PLUG ORIFICE IN CENTER OF FILTER CAVITY.
B. Install packing on filter and insert filter into filter cavity.
C. Position cover, then install by pressing cover down and rotating it clockwise.
D. Test safety relief valve (Ref Safety Relief Valve - Adjustment/Test).
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