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Compressor tank size for sprinkler system winterization?

Compressor tank size for sprinkler system winterization?

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  #1  
Old 09-16-20, 08:02 AM
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Compressor tank size for sprinkler system winterization?

Planning to DIY the winterization this year. I have a 5 zone system and would be blowing the zones out one at a time. I have a 10-gal compressor (4.5 SCFM @ 40PSI), which has been sufficient for most uses thus far, but I realize it's on the very low end for sprinkler blowouts. Would two blowouts per zone likely be sufficient, or would I be losing too large a % of the available air through the closer heads in each zone?

The alternative is selling the 10-gal and buying a 20 gal (the one I'm eyeing has 5 SCFM @ 40PSI). Two blowouts per zone probably enough with a 20-gal tank? Prefer not to have to jump to a 30-gal compressor given cost, size and the lack of need for other uses.
 
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Old 09-16-20, 08:48 AM
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It's not the number of zones, it's the length of each zone and number of heads.

10 gallon probably is not going to do it, 20 gal, maybe.

So here is something to consider, if you have the desire to upgrade that compressor you've got the perfect excuse.

Every time you have someone come out it's costing you what $35, $45 per year. Over 10 years you've paid off a pretty good chunk of that compressor.

A nice 60 gallon 5hp can be had for $500. Ive been doing mine for 30 years and I have long ago paid that thing off many times over!

Once you have that compressor installed and hard plumbed you will be amazed how often you use it, I could never consider not having compressed air at my disposal!
 
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Old 09-16-20, 08:43 PM
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Even 20 gallons is borderline for sprinkler blowout.
You'd need to charge it and blow out each zone several times.
 
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Old 09-17-20, 07:43 AM
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Given that water expands ~10% when it freezes, you don't need to get all the water out, right? Seems if I got even 50% of the water out, that would be sufficient. Or am I not thinking about this correctly?
 
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Old 09-17-20, 08:34 AM
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In theory your correct but what if you have a dip in the pipe and the 50% of the water from the high spot flows down to the low spot, now you have 100% water!
 
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Old 09-17-20, 09:00 AM
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Right, and I guess if the low spot is long enough and freezes quickly enough, the expanding freezing water will get blocked by ice before it can expand toward the empty part of the pipe.

So if I get a 20-gal compressor, as long as I blow out a zone and can see that the last sprinkler head on that zone rises, shoots out water, and then shoots out mist, then that zone should be sufficiently clear, right? And if I don't get the last head to rise and shoot mist, then I either need a larger compressor, or I can close off earlier heads in that zone until I get mist blowing out of the last head.
 
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Old 09-17-20, 04:17 PM
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You will only get short bursts of high pressure. It's those short burst that will do most of the work.
When in doubt..... send a few more blasts thru.
 
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Old 10-01-20, 05:09 AM
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You will only get short bursts of high pressure. It's those short burst that will do most of the work.
When in doubt..... send a few more blasts thru.
Does it make sense to use a 1/2" hose instead of 3/8" on a 1.6HP 20-gal compressor for this purpose? Or maybe go with 3/8" hose and high flow couplers?
 
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Old 10-01-20, 02:59 PM
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The more volume you can get into the sprinkler system.... the more effective it is.
 
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