b.
Additional Clearance for Bulky Clothing. The dimensions given in
(1) and (2), above, are valid for light work clothing only. An additional
allowance of 10 to 20 percent may be necessary for bulky clothing and
accessories. Heavy clothing has two primary effects. It increases the
anatomical dimensions, that is, arm and thigh thicknesses, and reduces
mobility parameters such as leg movement and forward arm reach.
c. Clearance for Door. In conjunction with door sizing requirements,
the designer should consider interior clearances affecting movement of the
door.
3.
CLOSING MECHANISMS. Closing mechanisms, whether quick or slow acting,
consist of a means for locking, for sealing, and a method of suspending the
door on hinges.
a.
Quick Acting. Several types of quick-acting commercially available
doors have become available for hyperbaric chamber use. These include the
breech-lock, the split-clamp type, and the multiple-lever type segmented
ring.
(1) Breech Lock. An example of a breech-lock door on a service
lock is shown in Figure 3-21. The cylinder flange and door are held together
by interlocking lugs. The door rotates 30 deg. to engage the locking lugs.
An O-ring establishes the seal when pressurized.
(2) Split Clamp.
A split-clamp door shown in Figure 3-22 is held
closed by the wedging action
of the split clamp. It is very much like the
breech lock, except that the
locking-ring motion is substantially radial
instead of circumferential.
The two halves of the locking ring are usually
driven by synchronized screw
actuators as illustrated, although hydraulic
actuation could be used.
(3) Segmented Ring. The segmented ring shown at Figure 3-23 is a
relatively quick and convenient type of closure which has been used
successfully for CO2 scrubbers.
b.
Swing Bolt. The swing-bolt closure is intermediate between the
quick-acting door and the bolted flange. The pivoted bolts make the door
much more convenient to open than a bolted flange, since the nuts need only
be loosened enough to pivot the bolts out of the way. However, if the number
of clamping points approaches that of a typical bayonet-type door, the
operating time increases significantly. The typical service lock shown in
Figure 3-19 has this type of outer door and a commercially available model is
shown in Figure 3-24. The advantages of the swing-bolt door are its
availability and modest cost.
c.
Alternate Closing and Locking Devices. Alternate closing and
locking devices which are not easily opened, but are simpler and cheaper are
suitable for infrequently used closures. These include the conventional
bolted flange and the clamping-bar closure shown at Figure 3-25. Many other
styles are readily available.
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