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xltraveler

Unregistered

1

Friday, January 4th 2013, 6:08pm

Why won't this beast blowout?????

I am trying to blowout a large irrigation system. The mainline is 2" thinwall SCH40, 1" SCH40 feeder lines, and then black poly running out to the sprinkler heads. There are 11 zones with the last zone valve being at least 1000 ft from the back-flow preventer. First I tried my portable compressor (under 5 cfm) @ 50 psi. I know you laughing now...so I don't have to explain how that went. Then I went and rented a 20cfm compressor from Sunbelt Rentals. That went exactly like the first attempt. Then I decided to use the commercial compressor (it was at a factory) inside the business and run 300 ft of 3/8" airline from that at 50psi. STILL NOTHING. So I hooked the water back up to be sure I didn't have a break somewhere and the water has no problem pushing the heads up.

Am I just WAY short in cfm on my compressor? I would have thought that an industrial compressor from the factory would have made short work of it. Instead, I spent 4 hours and didn't get anywhere.

I was connected to the system just past the backflow preventer. No air leaks in the line or connection.

Opinions welcome, smarta** remarks...not so much.

Wet_Boots

Supreme Member

Posts: 4,076

Location: Metro NYC

2

Saturday, January 5th 2013, 8:27am

"300 feet of 3/8" air line" is all we need to know - the pressure loss in that is probably off the charts

xltraveler

Unregistered

3

Saturday, January 5th 2013, 7:49pm

Increase pressure??

Should I just increase the pressure in order to compensate or do you think that I will be flirting with problems? My only alternative is to rent a pull behind compressor or bring in someone else who has one.

Wet_Boots

Supreme Member

Posts: 4,076

Location: Metro NYC

4

Sunday, January 6th 2013, 12:57pm

Very high pressure would do damage to the system. Air flow does the winterizing, not the air pressure. For the money, you could try a larger-diameter hose with the on-site air supply. Not cheap garden hose. Either rubber air hose or hot-water rubber garden hose of at least 3/4-inch inside diameter. Depending on the temperature of the air, you might be able to use the modern "all-season" garden hoses that are made of a special polymer something like rubber.

xltraveler

Unregistered

5

Monday, January 7th 2013, 1:02am

slowly increasing pressure?

I was thinking of putting a pressure regulator/gauge at the end of the 300 feet of 3/8 line and slowly turning up the Pressure at the supply end until i have 50 psi at the end of the length of hose. I thought maybe i could compensate for the pressure loss that way. I'm not trying to beat a dead horse, only seeing if i have a solution that doesn't require additional equipment/tools. The hose is rated at 300psi so i doubt i would even be remotely close to needing that much to compensate.

Thanks for your responses....they have been very helpful.

Wet_Boots

Supreme Member

Posts: 4,076

Location: Metro NYC

6

Monday, January 7th 2013, 3:43pm

As long as you plan to restrict the airflow with 300 feet of 3/8-inch air hose, you are dead in the water.

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