[Greenbuilding] [BULK] Re: Fire ratings and P U foam

[Speireag Alden]

Sgrìobh Lawrence Lile:

>Have any of you considered residential sprinklers?  I have seen some in
>residential mechanical rooms a time or two.  A couple of heads in key
>risk areas might modify your chances dramatically.

     During my addition and re-wiring and re-plumbing of the existing 
house, I'll be putting residential sprinklers in.  I dropped by my 
local fire department to get recommendations.  I'll be putting in 
3/4-inch PEX.  If I wanted it to be to code, I'd have to put a 
gas-powered pressure tank on the system.  It senses a sudden pressure 
drop and releases its capacity into the system.  However, my local 
code doesn't have anything to say about sprinklers, and any sprinkler 
is better than no sprinkler, so I'll do it as makes sense to me.

     However, I have a well with lots of capacity, lots more pressure 
tank than usual, and a well pump capable of 17 gallons per minute, so 
I'm going to rely on the existing system to power the thing.

>If you
>keep lines short, a stub can be run off of a regular domestic water line
>to a head, say, near the furnace and water heater or near the stove. 
>
>If these lines are more than a couple of feet long, you'll get stagnant
>water in there that you don't want in the same system as your drinking
>water.

     I've read that eighteen inches is the maximum length for a dead leg.

>Conventional sprinkler systems always use a device called a
>backflow preventer that isolates the nasty sprinkler water from the
>fresh drinking water.  For any kind of coverage besides a few spots,
>you'll be looking at some kind of backflow preventer and dedicated
>piping.

     You could also run the pipe out to the sprinkler and then back, 
to continue on to the next one.  It increases the pipe length, but 
eliminates dead legs.

     If your sprinkler system is connected with your potable water, 
it's a good idea to put a regular low-flow load at the end of the 
line, and a check valve where the sprinkler pipe starts.  I'm going 
to put the toilet and the bathroom sink there.  It won't draw enough 
water to cause condensation on the pipes, but it will be enough to 
refresh the water in the pipes regularly with cool water.

>Also, once a head blows off, that water won't shut off until someone
>thinks to turn off the main, usually several hours later.  If you have
>sprinklers, and a fire, you WILL have a flood.  Plan for that in your
>design - where is the water going to go?  Will it fill up the basement,
>or are there plenty of floor drains?

     A very good point.  Plumb so that drainage is easy and automatic.

-Speireag.

-- 
Anger, if not restrained, is frequently more hurtful to us than the 
injury that provokes it.
--Lucius Annaeus Seneca, philosopher (BCE 3-65 CE)