How much air pressure to blow out sprinkler system ??

A friand of mine bought a new house, complete with a built in sprinkler system. With cold weather coming, he knows he needs to winterize the system, which is equipped with a quick-connect air fitting. He's assuming he's supposed to hookup an air hose and purge the system with air. Question is : how much pressure to use ?? ?? ??
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Your looking for volume not pressure per say. Are you going to remove the heads or just blow it out?
If your going to blow it out then use 200 psi, and let me know when so I can come by with my camera.
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What is the normal working pressure? Just city water main pressure? What's that, about 50 psi or something? Probably no need to exceed working pressure and a bad idea I would think, if you are leaving the heads in place. The other idea, if there is water in the section you need to blow out, is just to ease on the pressure gradually and watch the water flow out the drain at the other end using just enough pressure to do this. If it's a fairly flat run between the two point then only a few lbs would probably do it. If you have verticals connecting floors then a bit more.
Is there a way you could push 50/50 antifreeze/water solution through the affected area so it could just sit there?
This is just reasonable speculation. Maybe someone more knowledgeable will know for sure.
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There are a couple websites which explain this process. Try Rainbirds site, or do searches. Don't confuse pressure with volume. You need a high volume compressor, which most homeowners don't have. You can rent a high volume compressor, or just pay someone who does this service. We're talking 25+ CFM airflow at a relatively low pressure- 20 psi or lower. Do not equate water pressure with air pressure. If you go with 50 psi, you may end up blowing your sprinkler heads into orbit, and or melting your sprinkler components. Compressed air gets hot. You can't use a typical 120v air compressor (6 - 10 cfm) and make up for the low airflow by increasing the pressure.
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"Do not equate water pressure with air pressure. If you go with 50 psi, you may end up blowing your sprinkler heads into orbit, and or melting your
sprinkler components. Compressed air gets hot. You can't use a typical 120v air compressor (6 - 10 cfm) and make up for the low airflow by increasing the pressure. "
LOL!
The sprinkler system works with over 50PSI water pressure, but 50PSI air pressure is going to blow it up? Or melt them? Now that is really hysterical! Sure, air gets hot when it's compressed, which is why the compressor gets hot. But when air expands, which is what it'd doing when it leaves the compressor and goes into the sprinkler system, it gets cold. That's how an air conditioner works.
I've blown mine out for 8 years with a 6 CFM Sears unit with maybe an 8 gallon tank. I let the pressure build to about 60 lbs, then turn on one zone. Let it run for a couple mins, then turn off the zone, let the pressure build back up, then do the next zone. Go through this process twice for each zone. It's not as fast as using a high CFM compressor, but it has worked well for me and saved me $500 so far!
Also, if you google, you'll find another recent thread on the same topic.
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