2�9�4 Helmet Attachment To The Diver - Kirby Morgan 77 Operation And Maintenance Manual

Kirby Morgan 77
®
The KMDSI Overpressure Relief Valve, (part num-
ber 200-017) is fully adjustable and serviceable and
has been designed to relieve any over-pressurization
of the first stage regulator greater than the desired
setting.
Every bailout (Emergency Gas System or EGS) first
stage regulator must be fitted with an overpressure
relief valve to prevent over pressurization of EGS L.P
hose in the event the first stage develops a "creep"
(i.e., leaks pressure).
WARNING
Be sure the Emergency air/gas first
stage regulator is fitted with a relief
valve for over-pressurization of the
emergency gas supply hose. A leaky
first stage can overpressure the hose
resulting in hose rupture. This would
cause a loss of the entire emergency
gas supply, with possible serious injury
or death.
The over-pressure relief valve
should be installed on every first
NOTE: This valve can be adjusted for various
relief pressures.
20
stage used for bailout.
KMDSI Part #200-017
© ⅯⅯⅩIⅡ Kirby Morgan Dive Systems, Inc. All rights reserved. Document # 130318003
The diver should always be equipped with an
emergency gas system.
CAUTION
Your emergency air/gas supply on a
deep mixed-gas dive is extremely lim-
ited. All divers must be aware of exactly
how long their bailout bottle will last
at depth. For example, a diver breath-
ing one cubic foot of air a minute at the
surface will use a 50 cubic foot bailout
bottle in approximately 7 minutes at 198
FSW while at rest.
2.9.4 Helmet Attachment to the Diver
On the KM 77, the ring on the base of the helmet
shell has a machined O-ring sealing surface. The
O-ring that seals against this surface sits inside the
neck dam ring assembly. The neck dam ring is actu-
ally a two part ring, consisting of the upper split ring
and the lower stepped ring. The neck dam is captured
(sandwiched) between these parts.
The locking collar and neck pad assembly has a
smaller opening than a diver's head so the helmet is
almost impossible to accidentally dislodge. The neck
pad pushes against the neck dam and lower portion
of the head cushion firmly securing the helmet to the
diver's head. The neck pad also helps prevent neck
dam ballooning. Each diver must personally adjust
the fit on his helmet by adjusting the neck pad, as