Sprinkler Blow out question:

[Ramsker]

Since it's supposed to warm up again and I'm trying to get my poor front lawn to recover, I'll probably just drain down to the manifold and the inside valve. Then I can just turn on the inside valve after it warms up and I'm good to go again.

I'm kind of thinking I'll do that same kind of thing. I have one drip line above ground and one zone in front with a section above ground that are susceptible to freezing. Will probably drain out the breaker/pipes & manifold and blow out those 2 zones real quick. Then will start it back up after the cold snap and run the system another couple weeks while it's warm. It's kind of a pain, but probably less than manually watering several times.

Might all be fine covering up the outdoor lines and riding it out . . . but the drawbacks if it freezes far outweigh the work to play it safe.

[Gman]

Fortunately I have enough grade that the sprinklers naturally drain pretty well when I open the valves. I've gone winters without blowing out with no ill effects.

[Martinjmpr]

OK, I'm trying this again. I figured out what I did wrong last year (it had to do with the little screw on the side of the air inlet) and plugged my little Porter-Cable compressor in last night.

It seemed to work OK on the closer sprinklers but on the ones farther away, it didn't seem to have enough 'power' to blow them out.

So here's my question: What specific "number" do I need to be looking at to give me enough power to blow the sprinkler lines?

My current compressor is as follows:

Porter Cable C2002 Compressor

PSI: 150 max
Tank: 6 gallons
2.6 SCFM @ 90 PSI

So what "number" do I need to be bigger? Would a bigger tank help? A bigger SCFM rate?

I don't mind shopping around for a new compressor, but whatever I get, I want it to be big enough to blow my sprinkler lines once and for all (without damaging them, obviously.) I had my compressor running for ~ 2 hours yesterday (I'm sure my next door neighbor hated me!) just trying to get it to get up to 150 PSI before I turned the pressure on to the sprinklers, but it would give me one "blast" of pressure and then not much more after that.

[Martinjmpr]

OK, so what I'm reading on the Intertoobz says that the required minimum SCFM is 20. Nothing I would be interested in buying is even close.

So it looks like I'll call my sprinkler guy again. He will blow them for $35, and I can't even rent a 20 CFM compressor for less than probably $60 or $100.

[Ramsker]

OK, so what I'm reading on the Intertoobz says that the required minimum SCFM is 20. Nothing I would be interested in buying is even close.

So it looks like I'll call my sprinkler guy again. He will blow them for $35, and I can't even rent a 20 CFM compressor for less than probably $60 or $100.

Required minimum of 20? Nah . . . you can do it with less CFM than that, it just takes longer and sometimes multiple passes at each zone (if you are paranoid like me). I have a 33 Gal Craftsman that I got on CL years ago and it's rated at 8.6 cfm @ 40 psi. Takes a little time but it works fine.

I've heard people say they use even smaller compressors than that. But I tried it with a 15 gal I have and it just didn't have the oomph for my setup. That's why I had my eye out for something like the above.

[Erni]

I read 8cfm at 40psi is good enough and I think that is right. I had 2 compressors siamesed once and it was about 9cfm, which did the job quickly.
By default I run my Kobalt oilless which I think does about 6cfm at 40psi. This rewuires two cycles but no issues for the past dozen years.

[Gman]

The issue for me is tank volume. You can dump a lot of air through the lines pretty quickly. If the pressure drops too low the backflow preventer will lose its seal. Once that happens, I have no way to get it to reseal using just air.

[Erni]

The issue for me is tank volume. You can dump a lot of air through the lines pretty quickly. If the pressure drops too low the backflow preventer will lose its seal. Once that happens, I have no way to get it to reseal using just air.

There should be a cutoff valve between your valves and your back flow preventer. Your air hook up should be after the valve to the bf.
Project time!

[Gman]

There should be a cutoff valve between your valves and your back flow preventer. Your air hook up should be after the valve to the bf.
Project time!

The air connection is after the BF, but there is no valve between the air connections and the BF and no room to insert one. It's easier for me to be careful than to re-engineer the plumbing.

[mahabali]

I’m thinking I may just unhook hoses and cover exposed pipes. I blew out sprinklers early Oct 2 years ago and then it got nice for a month and my yard turned brown.