For chamber doors, the O-ring is retained in a dovetail groove in the door
with about 15 to 20% of the ring projecting beyond the face of the door.
This seal is illustrated in Figure 3-34.
DOOR AND CLOSURE LOCATION. The designer is not afforded much freedom in
locating doors for personnel or equipment transfer. The most common location
for large doors is at one end of the PV (horizontal entry). This is
reasonably convenient for personnel, takes no wall space, and is favorable
from the standpoint of pressure-vessel integrity.
If the PV is to be partially flooded for some experiments, a vertical entry
hatch is very useful, since personnel can enter and leave the PV without
draining it. A vertical entry hatch is also helpful for installing equipment
and rigging cables for instrumentation in the PV. Heavy items can be lowered
into the vessel with a hoist.
LOCK SPACES. A lock space is required on a PV to allow the transfer of
personnel or equipment into or out of the PV without depressurizing the work
chamber. The lock space must be large enough to accommodate the persons and
equipment being transferred together with the opening of the outer and inner
doors. The lock space with the outer and inner doors must be designed for
the same pressures and pressure differentials as the rest of the PV.
SAFETY INTERLOCKS. The use of safety interlocks is recommended on all
PV service locks which have a hydraulic, electric or mechanical assist
mechanism for opening the service lock doors. The safety interlock must
prevent the opening of a door that is under pressure and permit the door to
be opened when the pressure on both sides is equal. Although there are many
ways to make a safety interlock, the use of hydraulic or electrical methods
should only be used to support a basic mechanical system. All service locks
should have a pressure gauge mounted on the lock where it is easily seen by