"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.