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Chapter 5 — 14
STANDARD DRESS
or
HARD HAT
This traditional piece of equipment uses compressed air delivered by a flexible hose to a rigid brass
or copper helmet, usually connected to a heavy duty dry suit. The depth of the dive determines the
pressure of the delivered air. A continuous air flow is supplied to the helmet at a rate sufficient to
supply the diver's oxygen needs and to flush out exhaled gas. Originally hand powered compressors
were used, later superseded by motorised compressors. A bank of compressed air cylinders can also
be used, as with SSBA.
This system is bulky and requires heavy lead weights (usually boots and chest corsets) to offset the
buoyancy of the helmet and the suit. Failure of the gas supply to keep up with the diver's rate of
descent, or loss of the air supply (in the absence of a non-return valve), can lead to the diver being
compressed into the helmet — causing head or body barotrauma. See Chapter 12.
Fig. 5.13
Fig. 5.16
A "hard hat" or
standard dress rig.