Blow out Sprinklers with Compressor?

How do I know if the compressor I bought to power my finish nailer is strong enough to blow out my brother's sprinkler system?
It's just a little pancake compressor (Porter Cable, 6 gallon tank), it says it can do 3.7 cfm at 40 psi or 2.6 cfm at 90 psi, but I'm thinking those are continuous numbers? And I need like 10 cfm but only for like 30 seconds?
Thanks! Chris
p.s. More proof there are too many lawyers ... the owner's manual includes, in the hazard section, a warning that if you put it on a table/workbench/roof, it might fall off and hurt you. Duh!
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I can blow mine out with my shop vacuum. I imagine your compressor can do it. <s>
djb
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All I know is that the people who serviced our sprinklers at the old house had a BIG compressor It just fit in the bed of their pickup. They kept air on the pipes until no more water sprayed out, which I would assume would take more air than a pancake could generate.
So a pancake or shopvac might be able to push water out of the system, but that doesn't mean it's getting all the water out, or even enough to prevent ice damage if the remaining water collects in a low spot.
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Fire sprinkler or lawn sprinkler? 10 cfm times 0.5 minute = 5 cfm - it's quite underpowered. Many pancakes are: 1 - oilless (will get quite warm when run continuous) 2 - intended for very intermittent loads (nailers/staplers) which do not use much air My 2HP 4 gallon unit gets very hot when I fill up several car tires in succession.
Instead of having to buy a replacement compressor, go rent one of the compressors used to drive a jackhammer (90 cfm) and be done with it. That's what the electricians use to blow a fish tape down an underground conduit. The wires are then pulled through with the fish tape.
Better safe than sorry.
On Wed, 21 Jan 2004 17:22:56 -0700, "Chris Shearer Cooper"

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You need a pretty good-size compressor for sprinklers. Yours couldn't put out 10CFM for more than a few seconds, and you need more than that to do a decent job. The sprinkler guys I've seen use great big gas-powered compressors and let them run for 15-20 minutes.
A shop-vac will provide the volume you need but not quite the pressure.
GTO(John)

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do the math:
6 gallons is somewhat less than 1 cu ft. Approximately 0.8 cu ft, in fact.
At +90 psi (6 atmospheres above ambient), there's just about 4.8 cu ft 'usable' air in the tank.
In 30 seconds (1/2 min.), the compressor could contribute another 1.3 cu ft.
You're now up to 6.1 cu ft out of the 10 you claim you need.
Find a 15 gal tank that you can pressurize to 90psi and you've got the 30 seconds @ 10 cfm.
If I'm doing the math right, charging that 15 gal tank to 90 psi should take only about 5 minutes.
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It's not. There is a reason that the lawn service guys use those huge compressors. The smaller ones will provide the pressure but not the volume necesarry to clear the lines. What will happen if you use on of these is that most of the water will clear, but you will still ahve water pooled in the lowest parts of the lines. If your lines are deep enough (they almost never are) to avoid freezing then it doesn't matter, but otherwise you will find ruptured lines in the spring when you turn the water back on. In a previous life I did lawn sprinkler installations and every spring we would do dozens of repair calls on systems where homeowners had attempted this. You also have the problem of how to connect your hose to the blowout. In any event, it is probably not worth the trouble or risk to save the $40.00 or so that the sprinker guy charges.
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For reference I have a 12 zone system that I blow out in the fall with my 10 CFM @ 90 PSI compressor. It is marginal to do the job. It takes me all day because I allow the compressor to cool down between each zone. The compressor is 5 HP and has a 33 gal tank but is not rated for continuous duty. Boy does it get hot.
<Secret> wrote in message>

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BTW, what is the reason for blowing out a sprinkler system? In 13 years in Texas, I have never done so. I have repaired it several times due to driving over a line or damage while planting a shrub. What would be the benefit of doing so? Leaving water in the lines is not usually a problem since my lot has significant slope and the excess drains out of the lowest head.
On Wed, 21 Jan 2004 17:22:56 -0700, "Chris Shearer Cooper"

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A properly installed sprinkler systems has drain valves to make sure that there is no standing water in the pipes. However, many installers save time and money by leaving these out. If water is left in the system you may have a problem. In 30 years in Dallas I never had a problem. In my other home with a 36" frost depth, it is another issue altogether.
The issue with blowing out the system is that you need air volume more than you need high pressure. I large diameter air hose and fittings help. It's similar to the problems that you'd have trying to "pop" a tubeless tire after installing it on the rim with a nail gun compressor.
RB
Thomas Kendrick wrote:

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RB wrote: <snip>

<snip>
Whoa!!! Just so I know where NOT to winter over, please tell where your other home is.
ARM
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43.94598 N / 69.45293 W
The harbor is frozen over but it's great in the winter.
RB
Alan McClure wrote:

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RB wrote:

Maine
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Thomas Kendrick wrote:

Where you live in Texas, how often does the frost line get as deep as your sprinkler lines are buried?
Many of us live in areas where it gets very white for 3 - 4 (or more) months out of the year. Anything that can contain water without room to expand has to be either buried very deep, drained/blown out, heated, or filled with antifreeze. Not doing this can provide some very nasty surprises after the thaw.
ARM
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