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Sprinkler blow out DIY

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[OP]
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Jul 25, 2013
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Toronto

Sprinkler blow out DIY

Seen other threads for this but wanted to see if there are any recommendations based on others experience for my specific scenario.

I have a 20 gallon 5 CFM @40 psi air compressor
My entire home lot (home included is 50ft x 110ft...less than .5acre). Front lawn is about 1000 sqft and back is about 1000 sqft. Flat land. Blowout valve is about in the middle of the property.

Is my air compressor able to perform this job properly? Any recommendations?

Thanks!
20 replies
Deal Fanatic
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Oct 19, 2008
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Should be no prob, do one zone at a time.
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Dec 3, 2003
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Toronto
The rule of thumb my irrigation guys use CFM @ 40PSI should be minimum equal GPM demanded by the largest zone.

If your flow rate is too low, you'll discharge some of the water, then just blow air OVER the water in the lines. That water will pool in the low spot and you'll have freeze damage come spring.

If you have a system with a flow meter, check the meter to determine GPM.

If you don't have a flow meter, take a look at the nozzles in the heads.

My system pulls 20 gpm so a portable electric compressor isn't going to really get the lines purged.
[OP]
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Jul 25, 2013
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Toronto
JMWarren wrote: The rule of thumb my irrigation guys use CFM @ 40PSI should be minimum equal GPM demanded by the largest zone.

If your flow rate is too low, you'll discharge some of the water, then just blow air OVER the water in the lines. That water will pool in the low spot and you'll have freeze damage come spring.

If you have a system with a flow meter, check the meter to determine GPM.

If you don't have a flow meter, take a look at the nozzles in the heads.

My system pulls 20 gpm so a portable electric compressor isn't going to really get the lines purged.
so i guess its not as straight forward as i thought?
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Aug 9, 2004
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ya, most home units dont move much volume.
I eat the cost of my sprinkler guy to do blowouts....but I never use him to do openings or replace bad sprinkler heads.
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Jun 12, 2007
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Infiniti2011 wrote: so i guess its not as straight forward as i thought?
I think in an old post, I calculated that a 20 gallon compressor could deliver about 10 CFM @ 40 psi for about 30 seconds before the 20 gallon tank reserve capacity is exhausted. The limiting factor is the standard 3/8" air hose that's about 50 ft long which can only flow about 10 CFM
[OP]
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Jul 25, 2013
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thanks for all the feedback, any others with experience doing it themselves?
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Nov 28, 2016
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I was in the same worry as well like you, and then read posts about how its not enough, like above. Even the professionals that come, dont get all the water out. Its about getting the majority of it out, and out of the heads.

Even the pros dont get the lines 100% dry. It needs to be blown out enough so any water left in them when expanded wont do any damage. Which should be the majority of it, but not all

This fall will be my 3rd blow out myself. I did one zone at a time, multiple times, and I dont seem to have any leaks anywhere. No soft ground, the heads work like normal, etc I assume Im doing it right

Im not sure of the size of my air compressor. Its a mastercraft vertical one on wheels.

I can leave it plugged in to power and the hose reaches my blow out point on the side of the house.

I do each zone once, until the compressor is out of air. let it charge to full, then do the next zone. Rinse and repeat.

Then I start at the first zone again, and do the same. I usualy do it three rounds, until basically only drips of water are coming out the heads

I have 4 zones. I dont know the length etc because I dont know where the lines are burried, and as well, I dont care to figure it out

Am I doing it right, well I assume so, they worked for the last 2 springs fine.

You will need to setup the adapter as well that goes into the blowout area. But once you have that, you have it every season and ready to go

RFD is a great place for info, and as well to get info to make you second guess yourself because of information overload, and as well posts that are over explanatory to maker you worry over nothing as well.

JmWarrens post explains a lot, which as well can just confuse any begginner and frighten him to not do it, because it looks hard, when it isnt
[OP]
Member
Jul 25, 2013
289 posts
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Toronto
WikkiWikki wrote: I was in the same worry as well like you, and then read posts about how its not enough, like above. Even the professionals that come, dont get all the water out. Its about getting the majority of it out, and out of the heads.

Even the pros dont get the lines 100% dry. It needs to be blown out enough so any water left in them when expanded wont do any damage. Which should be the majority of it, but not all

This fall will be my 3rd blow out myself. I did one zone at a time, multiple times, and I dont seem to have any leaks anywhere. No soft ground, the heads work like normal, etc I assume Im doing it right

Im not sure of the size of my air compressor. Its a mastercraft vertical one on wheels.

I can leave it plugged in to power and the hose reaches my blow out point on the side of the house.

I do each zone once, until the compressor is out of air. let it charge to full, then do the next zone. Rinse and repeat.

Then I start at the first zone again, and do the same. I usualy do it three rounds, until basically only drips of water are coming out the heads

I have 4 zones. I dont know the length etc because I dont know where the lines are burried, and as well, I dont care to figure it out

Am I doing it right, well I assume so, they worked for the last 2 springs fine.

You will need to setup the adapter as well that goes into the blowout area. But once you have that, you have it every season and ready to go

RFD is a great place for info, and as well to get info to make you second guess yourself because of information overload, and as well posts that are over explanatory to maker you worry over nothing as well.

JmWarrens post explains a lot, which as well can just confuse any begginner and frighten him to not do it, because it looks hard, when it isnt
this gives me comfort haha ....what psi do you do it at? i'm reading 50 psi?
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Infiniti2011 wrote: this gives me comfort haha ....what psi do you do it at? i'm reading 50 psi?
I think thats what I have it at. Ill have to look. I wrote myself up instructions to follow so I know I dont miss something
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Jan 23, 2015
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WikkiWikki wrote: I was in the same worry as well like you, and then read posts about how its not enough, like above. Even the professionals that come, dont get all the water out. Its about getting the majority of it out, and out of the heads.

Even the pros dont get the lines 100% dry. It needs to be blown out enough so any water left in them when expanded wont do any damage. Which should be the majority of it, but not all

This fall will be my 3rd blow out myself. I did one zone at a time, multiple times, and I dont seem to have any leaks anywhere. No soft ground, the heads work like normal, etc I assume Im doing it right

Im not sure of the size of my air compressor. Its a mastercraft vertical one on wheels.

I can leave it plugged in to power and the hose reaches my blow out point on the side of the house.

I do each zone once, until the compressor is out of air. let it charge to full, then do the next zone. Rinse and repeat.

Then I start at the first zone again, and do the same. I usualy do it three rounds, until basically only drips of water are coming out the heads

I have 4 zones. I dont know the length etc because I dont know where the lines are burried, and as well, I dont care to figure it out

Am I doing it right, well I assume so, they worked for the last 2 springs fine.

You will need to setup the adapter as well that goes into the blowout area. But once you have that, you have it every season and ready to go

RFD is a great place for info, and as well to get info to make you second guess yourself because of information overload, and as well posts that are over explanatory to maker you worry over nothing as well.

JmWarrens post explains a lot, which as well can just confuse any begginner and frighten him to not do it, because it looks hard, when it isnt
I've been doing a similar procedure for the last 14 years, using only a 6 gallon air compressor. To this day I never had a problem with a blown joint or a sprinkler head failing. Just to note, I never go beyond 50 psi in air pressure.
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Dec 13, 2003
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I have done mine for years as well. The 50psi or below is key. If the PSI is too high then it can cause damage.

I used to use a small 5 gallon, now run from a 20 gallon but it won't make a difference really, just means the compressor will run a little less with a bigger tank.
[OP]
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Jul 25, 2013
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Bianco13 wrote: I've been doing a similar procedure for the last 14 years, using only a 6 gallon air compressor. To this day I never had a problem with a blown joint or a sprinkler head failing. Just to note, I never go beyond 50 psi in air pressure.
thanks this is all very helpful information to get all sorts of opinions , how long does it take you on average/how many zones? and any idea what the CFM rating is on your compressor?
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Jan 23, 2015
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Infiniti2011 wrote: thanks this is all very helpful information to get all sorts of opinions , how long does it take you on average/how many zones? and any idea what the CFM rating is on your compressor?
I air out the compressor 2-3 times per zone, total of 3 zones, property is 50ft X 130ft. Compressor is a 6 gallon producing 2.6 SCFM @ 90 psi.

The 20 gal compressor you will be using, is more than capable enough to handle this task. Just don't exceed 50 psi, set the compressor between 40-50 psi.
Newbie
Sep 8, 2014
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Oakville, ON
WikkiWikki wrote: I think thats what I have it at. Ill have to look. I wrote myself up instructions to follow so I know I dont miss something
[OP]
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Jul 25, 2013
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What size air hose are people using? My air compressor comes with 1/4 inch. Would it be recommended to buy a 3/8 or 1/2 inch hose or is the 1/4 inch ok.
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Apr 18, 2005
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Infiniti2011 wrote: What size air hose are people using? My air compressor comes with 1/4 inch. Would it be recommended to buy a 3/8 or 1/2 inch hose or is the 1/4 inch ok.
yea I'd go something bigger.. you cannot get enough volume with 1/4
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Infiniti2011 wrote: What size air hose are people using? My air compressor comes with 1/4 inch. Would it be recommended to buy a 3/8 or 1/2 inch hose or is the 1/4 inch ok.
1/4 air line X 50 ft @40 psi = 3.6 CFM max
3/8".......................................= 9.9 CFM max
1/2" ...................................... = 20.3 CFM max

https://www.rapidairproducts.com/techni ... calculator
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Dec 18, 2008
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Am I understanding correctly? The 3/8" line can have 1/4" fitting and still provide the ~9.9 CFM max?
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hobbes778 wrote: Am I understanding correctly? The 3/8" line can have 1/4" fitting and still provide the ~9.9 CFM max?
And away we go. This will now end up into some convoluted over thought confusing post to do something simple.

The quest for perfection, thats RFD

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