Question
Hi James, I installed my irregation system this past summer and I'm now ready to winterize it. My concern is how big of an air compressor I will need to buy in order to blow out the zones. I have 5 zones, ranging in length from 1400" to 2500" in total hose length (per zone). All hose is 3/4" flex tubing (.81" diameter). By my calculations I have a total of 2.8 ft^3 of hose i need to blow out. So, do you think a 5gal compressor with 7.6cfm @ 40psi would work? Also, each zone controll is an anti-siphon valve. Can I connect the compress upstream of that or does it have to come after? Same question for the backflow value, can the compressor be upsteam of that?

Answer
Greg,
you can do it with that compressor, but it wil take a very long time, because you only have the 5 gallon tank and if you think about the amount of pipe you have to fill which is 3/4' x 1400/2500 (inches"??) Then you  will have to fill up the pipe with air,turn on a zone. Let the compressor refill the pipes and go on like that. A bigger compressor would be quicker. What I would do is blow everthing out after Upsteam of the backflow and then after wevery thing is done hook up before the backflow and blow. JIm