At the last company I worked for I was on good terms with one of the
maintenance guys who explained to me that the sprinkler system in our
building was filled with air under some amount of pressure (he didn't say
how much). Somewhere in the system (presumably at the main water supply)
there is a valve that stays closed until the air pressure in the system
drops below a certain point, at which time it opens and lets the water
flow. Thus, when a sprinkler head senses a fast rise in temp and opens up,
it's letting the pressure out of the system which starts the flow of water
from the main supply. The air in the system is never in contact with the
water until pressure drops and the valve is opened.
Makes sense to me but I can't verify any of this. It's just what I was
told.
Mike Frerichs
maf@radiks.net
Ken Landaiche wrote:
> I thought the pipes of sprinkler systems were filled with a gas of some
> sort to eliminate rust from years of standing water. But I don't know
> how the gas would not get absorbed by the water over time. My old well's
> 18 gallon pressure tank used to need draining every few months because
> the water absorbed the air. That was before they started using sealed
> air bladders in pressure tanks. Maybe the one inch of air/water contact
> in a sprinkler system would not absorb much of the gas.
>
> Then again, it's been a few years since I set off any sprinklers, so
> maybe I'm all wet.
>
> Ken Landaiche
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