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MLI
10-08-2002, 03:01 PM
what size compressor would I need to blowout my own system? How much psi is needed? thanx

rvsuper
10-08-2002, 09:45 PM
At least a 10 CFM Compressor. Set the regulator at about 50-55 PSI. Run every zone for about 5 minutes or until no more water is spraying out.

MLI
10-12-2002, 10:59 AM
thanx for the info...:)

DanaMac
10-14-2002, 09:47 AM
Honestly. I don't know the size of the compressor I use. Basically it is a tow behind, diesel engine compressor that I get at the rental shop. I do have it set at about 80 psi though. Usually I can blow out 2-3 residential zones at a time and they only need a couple of minutes.

rvsuper
10-14-2002, 04:27 PM
You have any pics of how you hook up the compressor to the blowout point? I'm looking for a new way do do this. Right now, I blow out a baseball field with a 3" main and I rent a tow behind for that, and I hook up a key to the Rainbird Quick Connect Right after the PVB with the air hose hooked up to the key. Does anyone hook up to the test coc on the backflows?

HBFOXJr
10-14-2002, 06:05 PM
They restrict air too much. Depending on the GPM of the zones the single hook up may marginal.

With that size stuff we double hose and connect.
1. 2 hoses off the compressor to a double connection on the key

or
2. better yet, 2 hoses off the compressor with 2 key hook ups or threaded pipe inlets.

These larger jobs should have the equivalent of a RainBird #44 or #55 QC valve set up.

The common 50-75 ft 3/4" hose lengths really affect performance at the high volumes of air so 2 are much better.

To make an easy 2nd connection anywhere, you can buy snap on PVC saddles that bond up with glue. Very reliable and strong. Get a 3/4" hole saw to cut the hole after installation. Make sure you use a pipe size by 1" female pipe thread snap on "t". Install a pvc plug with teflon paste, no tape or pipe dope after your done.

Ground Master
10-14-2002, 07:35 PM
Good tip, Harold. I've seen many guys running what looks like 3/8" hose one might use for air tools.

I use a 5hp gas compressor that does a good job of blowing out residential systems. Its not a perfect setup, as occasionally I have to run through a zone twice. I use this setup for systems with a 3/4" water line, which is the majority in colorado springs. I even have an electric hose reel mounted on the truck which makes handling 3/4" hose a snap. I will try and post a pic soon.

I'll set-up my bigger blow-outs (commercial) on the same day and rent a tow behind.

rvsuper
10-14-2002, 11:03 PM
what do you use for smaller systems i.e. residentials?

Ground Master
10-15-2002, 10:03 AM
I've seen recommendations of 10 to 25 cfm for small systems as well as recomendations of 20 to 50 cfm for small systems (systems with a 3/4" mainline into the house).

I've been using a 5hp gas compressor for 10 years or so (10 cfm) with good results. It does have a 20 gallon tank that I charge up to 60 psi and then I open the valve SLOWLY. This has worked well for me, although I have seen that it is not recommended to build up pressure in an air tank. I suppose the sudden rush of air can cause to much heat.......but I think if you can control the flow you can reduce the risk.


I'd like to rent a bigger compressor in the 12 to 13 hp range (25 cfm) to see how well they work for residential systems. I think these units may be a good compromise between a small setup (like mine) and the big tow behind units.