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Tim McShane, Assistant--Cultural History
Medicine Hat Museum and Art Gallery
1302 Bomford Crescent S.W.
Medicine Hat, AB   T1A 5E6
(403) 502-8587
[log in to unmask]

>>> [log in to unmask] 01/28/05 10:38 AM >>>
My understanding from previous discussions is that dry-pipe systems are
preferred? 

That was my understanding as well, until we solicited some expert
advice from a heritage building design consultant.  His opinion was
that, unless you're able to go with a very expensive system that will
flood the dry pipes with oxygen-excluding gas (nitrogen is one option),
residual water in the pipes from annual tests of the system (required
where we are--may not be where you're located, but still a good idea!)
in contact with air will rust-out your pipes prematurely.  There's also
the effect of the "water hammer" hitting the sprinkler heads each time
the system is flooded for testing--this will also be a factor in
premature wear.  Finally, rust in the pipes will dirty the water that
will come out of the system in the event of a fire--this will be much
worse for your collection than clean(er) water from a wet-pipe system.

Other factors in favour of the wet-pipe system was delivery time in the
event of fire--no waiting for the pipes to flood before water can be
released.  We also had it pointed out to us that water-damaged artefacts
can often be conserved and restored--burned ones are permanently
damaged/destroyed.

I was also interested in the new gas systems that have come out
lately--our consultant was cautious of them, as they hadn't been around
long enough to prove their worth, or their hazard to people.  It's been
almost two years now since we made our decision, so the gas systems may
be considered more reliable now--I don't know.  At any rate, they're
sure to be more expensive to install and maintain than a water system.

Given all the above info, we were advised to go with the single-stage
wet pipe system.  That's what we got.

Cheers,



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