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Operation. When the mine is dropped, it sinks rapidly to the bottom,
with a resuling rapid increase in hydrostatic pressure head, proportional to
the depth of water. This pressure is transferred to X, which is compressed
thereby. Compression of X creates a pressire differential between X and Z,
causing the diaphragm to move inward toward Z and opening the switch wider
than usual. The pressure differential leaks off through C, and, when it has
been reduced to zero, D and the fixed contact resume normal condition and
contact gap (0.007 in.). |
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Any negative
pressure differential on X, equal to about 2½ inches of water, will cause X
to expand and allow the contact to close, provided that the change in
pressure occurs quickly enough. Pressure differential caused by natural
causes such as tides and seiches occurs over periods too long to be
effective, since C allows the pressure to equalize without expanding the
diaphragm sufficiently to make contact. However, large pressure differential
caused by action of a ship, or even by a large wave or swell, will affect
the diaphragm sufficiently to close the contact, since C cannot equalize the
pressure rapidly enough. From this point on, the associated electrical
circuits of the pressure component govern further operation, with the
pressure-detecting deveice serving only to close its switch for the duration
of the pressure differential. |
