On Jan 19, 9:30 am, " wrote:
... I'll dive into my spare parts cabinet and look at it
again if I get some time. ...


Right, I just took it apart and put it back together. It is a Hammar
H20 E "for EPIRB use only". The insides are pretty much as I
remembered them. The major working parts are a knife and spring held
in place by a pin that is attached to a diaphragm that is held in
place by another spring. When it operates water pushes against the
diaphragm through two hollow pins on the knife side of the device
forcing the diaphragm into the low pressure chamber thus pulling the
retaining pin out and releasing the knife. The one I have sat in my
EPIRB in my cockpit for years and looks and operates like new.

There is one mysterious feature. On the top of the pressure casing
there is a small resin colored plug. It is visible from the outside
of the case through a hole in the label. I presume this keeps the
device from exploding if you take it up into space or something. On
the other hand it could be the little bit that dissolves every two
years so you have to replace it... Or, perhaps, they use the hole to
fill the chamber with inert gas... In any case, if the bung were out
the device would not operate. I suppose it is worth looking to make
sure it is there periodically, particularly if the release has been in
an airplane.

-- Tom.