EPIRB launcher
 

"Geoff Schultz" wrote in message
.. .
"Capt. JG" wrote in
:

"Geoff Schultz" wrote in message
.. .
Red wrote in
:

Anyone have any knowledge or experience with the hydrostatic release
module that is inside the case that launches the EPIRB when the boat
is sinking? Specifically the one I am inquiring about is the Hammar
model H20 E. It says on the top that you should replace after 2
years of "use", but what if the unit was manufactured longer than a
few years prior? If the manufacture date is 2005, but has been
deployed in the case for only one year since purchase - would the
unit still be good and reliable? I am not familiar with the internal
workings of these units, are they a form of explosive charge (making
them more susceptible to failures over time similar to flares), or
just spring loaded? Any other info I should know? Thanks
Red

I have one of these and have found the replacement hydrostatic
release part
on the Internet. This is the same part that I have on my liferaft.

I believe that it's a mechanical part with a sharp blade that cuts
the rubber retaining rob in the EPIRB unit and (I think) a line for
the life raft. I tend to replace them every 2 years. They aren't
cheap.

I've taken an old unit diving with me to see if it would "fire". It
did and there wasn't any explosive sound. I suspect that it's a
pressure activated release on a spring. The problem is that there's
no way to inspect it and it's a one time use device.

-- Geoff
www.GeoffSchultz.org


Isn't that the definition of hydrostatic... pressure release?

Yes it is, and I was simply stating that it wasn't an explosive charge and
instead a mechanical cutting device triggered by pressure. I'm not quite
sure what point you were trying to make other than perhaps to be a
smartass
and not add anything to the discussion.

-- Geoff
www.GeoffSchultz.org


Well Geoff, it seemed to me that you were asking if a hydrostatic device is
a pressure release mechanism. I suppose it's possible for this to actuate
something other than a spring, but that seems overly complicated. What did
you think it would activate?

That was my point, which if you'd have stated your question a bit more
clearly, would have contributed a great deal more to the discussion.

--
"j" ganz @@
www.sailnow.com

EPIRB launcher
 

"Capt. JG" wrote in
:

"Geoff Schultz" wrote in message
.. .
"Capt. JG" wrote in
:

"Geoff Schultz" wrote in message
.. .
Red wrote in
:

Anyone have any knowledge or experience with the hydrostatic
release module that is inside the case that launches the EPIRB
when the boat is sinking? Specifically the one I am inquiring
about is the Hammar model H20 E. It says on the top that you
should replace after 2 years of "use", but what if the unit was
manufactured longer than a few years prior? If the manufacture
date is 2005, but has been deployed in the case for only one year
since purchase - would the unit still be good and reliable? I am
not familiar with the internal workings of these units, are they a
form of explosive charge (making them more susceptible to failures
over time similar to flares), or just spring loaded? Any other
info I should know? Thanks Red

I have one of these and have found the replacement hydrostatic
release part
on the Internet. This is the same part that I have on my liferaft.

I believe that it's a mechanical part with a sharp blade that cuts
the rubber retaining rob in the EPIRB unit and (I think) a line for
the life raft. I tend to replace them every 2 years. They aren't
cheap.

I've taken an old unit diving with me to see if it would "fire".
It did and there wasn't any explosive sound. I suspect that it's a
pressure activated release on a spring. The problem is that
there's no way to inspect it and it's a one time use device.

-- Geoff
www.GeoffSchultz.org


Isn't that the definition of hydrostatic... pressure release?

Yes it is, and I was simply stating that it wasn't an explosive
charge and instead a mechanical cutting device triggered by pressure.
I'm not quite sure what point you were trying to make other than
perhaps to be a smartass
and not add anything to the discussion.

-- Geoff
www.GeoffSchultz.org


Well Geoff, it seemed to me that you were asking if a hydrostatic
device is a pressure release mechanism. I suppose it's possible for
this to actuate something other than a spring, but that seems overly
complicated. What did you think it would activate?

That was my point, which if you'd have stated your question a bit more
clearly, would have contributed a great deal more to the discussion.

I think that you're confusing me with the OP. I haven't asked any
questions. The closest thing to a question was my statement "I suspect
that it's a pressure activated release on a spring." Not having opened
one up, I wasn't sure how it operated, but I certainly understood that
hydrostatic is a synonym for "pressure activated."

-- Geoff
www.GeoffSchultz.org

EPIRB launcher
 

"Geoff Schultz" wrote in message
...
"Capt. JG" wrote in
:

"Geoff Schultz" wrote in message
.. .
"Capt. JG" wrote in
:

"Geoff Schultz" wrote in message
.. .
Red wrote in
:

Anyone have any knowledge or experience with the hydrostatic
release module that is inside the case that launches the EPIRB
when the boat is sinking? Specifically the one I am inquiring
about is the Hammar model H20 E. It says on the top that you
should replace after 2 years of "use", but what if the unit was
manufactured longer than a few years prior? If the manufacture
date is 2005, but has been deployed in the case for only one year
since purchase - would the unit still be good and reliable? I am
not familiar with the internal workings of these units, are they a
form of explosive charge (making them more susceptible to failures
over time similar to flares), or just spring loaded? Any other
info I should know? Thanks Red

I have one of these and have found the replacement hydrostatic
release part
on the Internet. This is the same part that I have on my liferaft.

I believe that it's a mechanical part with a sharp blade that cuts
the rubber retaining rob in the EPIRB unit and (I think) a line for
the life raft. I tend to replace them every 2 years. They aren't
cheap.

I've taken an old unit diving with me to see if it would "fire".
It did and there wasn't any explosive sound. I suspect that it's a
pressure activated release on a spring. The problem is that
there's no way to inspect it and it's a one time use device.

-- Geoff
www.GeoffSchultz.org


Isn't that the definition of hydrostatic... pressure release?

Yes it is, and I was simply stating that it wasn't an explosive
charge and instead a mechanical cutting device triggered by pressure.
I'm not quite sure what point you were trying to make other than
perhaps to be a smartass
and not add anything to the discussion.

-- Geoff
www.GeoffSchultz.org


Well Geoff, it seemed to me that you were asking if a hydrostatic
device is a pressure release mechanism. I suppose it's possible for
this to actuate something other than a spring, but that seems overly
complicated. What did you think it would activate?

That was my point, which if you'd have stated your question a bit more
clearly, would have contributed a great deal more to the discussion.

I think that you're confusing me with the OP. I haven't asked any
questions. The closest thing to a question was my statement "I suspect
that it's a pressure activated release on a spring." Not having opened
one up, I wasn't sure how it operated, but I certainly understood that
hydrostatic is a synonym for "pressure activated."

-- Geoff
www.GeoffSchultz.org


Ah... glad you understood. Sorry if my post seemed smartass-like... wasn't
my intention, although I am pretty good at it from time to time.

--
"j" ganz @@
www.sailnow.com

EPIRB launcher
 

" wrote in
:

On Jan 18, 8:16 am, Geoff Schultz wrote:
...Since you're just going to trash the hydrostatic release, tie a
string to it and drop it into some deep water and see if it works. I
think that they're supposed to go off at 13'. ...

I disassembled one that I'd replaced after 5 years of cruising and it
looked brand new inside and worked perfectly... I suppose they're
worried about the mechanism getting fouled by salt or something...
Anyway, FWIW it was easy to take apart and put back together.

-- Tom.

Inquiring minds want to know: What was in the inside?


-- Geoff
www.GeoffSchultz.org

EPIRB launcher
 

Red wrote in :

Ok, I've got some answers from some survival gear outfits. I'm told that
the service life on the release module is two years "in service"
regardless of manufacture date (providing its not *too* old) as long as
it is in good condition. So if it was manufactured in 2005 but purchased
in spring 2007 and put in service at that time, then it would be good to
go through spring 2009. The price I got on one was $147 plus shipping -
didn't check the net for it yet.
Red

You can get them for about $75 at http://www.marinewholesales.com/


-- Geoff
www.GeoffSchultz.org

EPIRB launcher
 

On Jan 19, 1:48 am, Geoff Schultz wrote:
....
Inquiring minds want to know: What was in the inside? ...

As I recall, there's a gasket / diaphragm, two springs a blade and
blade retainer. I'll dive into my spare parts cabinet and look at it
again if I get some time.

-- Tom.

EPIRB launcher
 

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.

EPIRB launcher
 

On Sat, 19 Jan 2008 17:25:39 -0800 (PST), "
wrote:

... 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.
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. ...
I suppose it is worth looking to make
sure it is there periodically, particularly if the release has been in
an airplane.

-- Tom.


...er.... It takes about 6 psi EXCESS pressure like 13 ft depth of
water to actuate the sprung knife?

Clear on up to outer space, there is no excess pressure I know of.
Or am I misssing something?

Brian W

EPIRB launcher
 

You can get them for about $75 at http://www.marinewholesales.com/

-- Geoff
www.GeoffSchultz.org

Thanks Geoff,
I looked it up and they are about half of the quoted retail out here. I
will send the owner this link then and let him take care of it.
Red

EPIRB launcher
 

...er.... It takes about 6 psi EXCESS pressure like 13 ft depth of
water to actuate the sprung knife?

Clear on up to outer space, there is no excess pressure I know of.
Or am I misssing something?

Brian W

I take it he meant that it may be there to release pressure *inside* the
case to keep the case from "exploding" in a low pressure environment,
not imploding as would be the case of external pressure when sinking.
Red