CFM required for 3” pipe winterizing

Wet_Boots

LawnSite Fanatic
Location
metro NYC
That’s exactly my concern.
Now if we only knew how many cfm is needed to accomplish that based on the pipe size
In both diagrams, the bottom of the center pipe is wide open. The buoyant air is pushing up the water, without any of the water falling back down into the air column. That would seem to defy gravity, but as an observed phenomenon requiring explanation, the minimal air/water boundary would make for a minimum of surface tension. This boundary area minimizing would explain why pushing high velocity air to the furthest sprinkler head(s) in a zone is not leaving behind a detectable amount of water.
 

cjohn2000

LawnSite Senior Member
Location
Tacoma, WA
I would be more concerned with the size of the zones GPM and the quick coupler size. YES you could run multiple zones but would the controller support that from a power standpoint? Maybe your bleeding the zones on manually?, then my question again is the quick coupler size OR your airline size. In my experience 90 cfm air compressor will blow out 40 gpm zones at 40psi dynamic.
 
OP
C

Clean Cut Lawns

LawnSite Senior Member
Location
Ossining, NY
I would be more concerned with the size of the zones GPM and the quick coupler size. YES you could run multiple zones but would the controller support that from a power standpoint? Maybe your bleeding the zones on manually?, then my question again is the quick coupler size OR your airline size. In my experience 90 cfm air compressor will blow out 40 gpm zones at 40psi dynamic.
i would have to say your spot on with the 90 cfm for 40 GPM with the 185cfm we can clear out about 80 gpm zones (or combined zones) with real good results (stays right around that 40psi)

as far as the number of zones at a time that could be anywhere from 1 zone for the sports fields to as much as 10 zones of sprays or smaller rotors, most of our larger sites are all 2 wire (decoder) systems those clocks don't have a problem running multiple zones at once.

but i still wonder is that 3" pipe getting complelely blown out or is air skipping over the top of water in some places since its rated at 120 GPM...
 

greenmonster304

LawnSite Platinum Member
Location
You Know
Yesterday I blew out a place that has a 4” loop with 2” spurs and 85 zones. I start by emptying the loop by pushing all the water out the furthest few zones. Once it is empty I turn on 2 or 3 30 gpm zones at a time. The 1200’ of 4” pipe acts as a 700 gallon storage tank. I haven’t had any issues with damaged pipes using my 185 cfm but I have never dug up th pipe to see if it is completely empty.
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Clean Cut Lawns

LawnSite Senior Member
Location
Ossining, NY
Yesterday I blew out a place that has a 4” loop with 2” spurs and 85 zones. I start by emptying the loop by pushing all the water out the furthest few zones. Once it is empty I turn on 2 or 3 30 gpm zones at a time. The 1200’ of 4” pipe acts as a 700 gallon storage tank. I haven’t had any issues with damaged pipes using my 185 cfm but I have never dug up th pipe to see if it is completely empty. View attachment 464606View attachment 464607View attachment 464608View attachment 464609
Same with me, most our sites are looped mains, mostly 2” & 3”

never had issues with freezing but always wondered if I’m getting all the water out.




But since boots knows everything with providing any helpful factual info….I guess no one else needs to chime in here

:rolleyes::rolleyes::rolleyes:
 

Wet_Boots

LawnSite Fanatic
Location
metro NYC
I think by the time a doubter on the phenomenon of surface tension between air and water became absolutely certain that enough air was blowing through the plumbing to clear out every last drop of water, the high-speed compressed (and heated by said compression) air might damage plastic parts not designed to withstand heat.
 

Michael - Toronto

LawnSite Member
...I start by emptying the loop by pushing all the water out the furthest few zones.
I think that GreenMonster's strategy makes a lot of sense, and will go a long way towards mitigating any concern about water left behind in the main line.

I follow a similar procedure: I always begin by blowing out the last zone way down at the end of the main line, and I'll blow that zone until I am satisfied that I have pretty much emptied the main line. Then, I'll start with the zone closest to the compressor, and work my way down the main line to the end and blow that last zone out one last time.

As for a little bit of water remaining in your 3 inch main line, I would not be too concerned about getting it 100% totally dry. Chances are it is buried pretty deep, and if you just have a wee bit of water in the bottom of the pipe, it's not going to damage the pipe if it freezes. The only concern would be if there is a U-shaped section of main line that could remain full of water, but if you follow the sequence I described above, it is unlikely any such sections will remain full.

Michael
 

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