Overpressure Relief Valve Reassembly - Kirby Morgan 77 Operation And Maintenance Manual

Kirby Morgan 77
®
7.15.3 Overpressure Relief Valve
Reassembly
1) After cleaning, inspection and/or parts replacement,
reassemble the valve by installing the soft seat, spring,
and adjustment nut. Screw the adjustment nut down
until it is approximately 1/2 thread from being flush
with the top of the valve body.
2) Lightly lubricate a new body O-ring, then install
on the valve body.
3) Test the relief/bleed valve according to the test
procedure below.
7.15.4 Overpressure Relief Valve Lift Check/
Setting
Tools required:
Adjustable first stage scuba regulator or controlled
adjustable pressure source
Intermediate pressure test gauge
Torque wrench
1/2" open-end wrench adapter for torque wrench
1/8" Allen wrench
HP air source {SCUBA tank) with at least 500 p.s.i.g.
(34.4 bar).
Mild dish soap
The purpose of lift checking the relief/bleed valve is to
ensure it operates properly, allowing excess pressure to
escape in the event the first stage develops a slight leak.
Without the relief/bleed valve, high-pressure gas will
continue to increase until the emergency supply hose
ruptures, possibly causing injury and a complete loss
of the Emergency Gas System (EGS).
This procedure explains the steps necessary for readjust-
ing the relief/bleed valve after it is cleaned, overhauled
or any time the valve is tested.
NOTE: The relief/bleed valve is lift checked and/
or adjusted using an adjustable first stage regulator,
WARNING
Ensure the relief/bleed
valve is only installed in
a low-pressure port of
the first stage regulator.
Installation in a high-
pressure port will lead to
loss of EGS supply and possible serious
personal injury if the valve fails.
120
supply system not designed and cleaned
for oxygen service, can result in a fire
or explosion causing serious injury or
death.
equipped with a low-pressure test gauge, which is used
for adjusting the intermediate pressure of scuba regu-
lators. The check/adjustment can be performed using
a standard scuba test stand, or a gas control console,
using air or mixed gas with an oxygen content below
23% by volume.
If a first stage scuba regulator is used, it must be able
to be adjusted to the desired lifting pressure. The
pressure gauge should be compared to a gauge of
known accuracy.
NOTE: If the Allen screw on the relief/bleed valve hex
nut is rotated too far, too fast, the relief/bleed valve
will pop open. This could possibly require the air to
be secured at the cylinder or supply source to reset
the seat before the adjustment can be accomplished.
NOTE: The relief/bleed valve can be installed in any
first stage regulator, providing the first stage has an
intermediate setting of 135 - 165 p.s.i.g. (9.3 – 11.4
bar).
1) Install the relief valve in a low-pressure port on an
adjustable 1st stage regulator. Or install on the scuba
test stand.
2) Install the intermediate pressure gauge in one of the
low-pressure ports of the first stage regulator.
3) Install the 1st stage regulator on the cylinder. Ensure
the relief valve and intermediate pressure gauge are
attached to low-pressure ports.
4) Wet the relief valve with soapy water to help indi-
cate gas flow
5) Slowly bring up air pressure while watching the
intermediate pressure gauge until the pressure gauge
indicates 180- 200 p.s.i.g. (12.40-13.78 bar). If the re-
© ⅯⅯⅩIⅡ Kirby Morgan Dive Systems, Inc. All rights reserved. Document # 130318003
WARNING
Do not use oxygen, or
mixed gas containing
more than 23% oxygen by
volume, for lift checking
the relief/bleed valve. The
use of oxygen, or mixed
gas, in a high-pressure