Pressure for blowouts

[cjohn2000]

Originally Posted by irritation

Naw, cjohn will have mowers and weedeaters in his sig next year.

We got four lawn crews to do that. More like hardscapes and lighting in my future

[1idejim]

Originally Posted by zimmatic

Largest compressor I have used was a 900 cfm. IMO its all about the cfm vs the pressure. I had several townhome systems and one small private homeowner golfcourse.
The largest mainlines were 3" and one townhome had 2 water sources and 3 clocks w/16zones each. What I was worried about was melting down the pvc after the rpz. Systems that large I remove all backflow devices, plus they usally are stored off site. 1 so they dont freeze and 2nd as an insurance policy to get paid.

It felt like all I did was make sure pressure was in check vs discharge air temp and pushing water in the correct directions since there were no isolation valves within the townhome systems.

When I rented the machine the first year I thought I was going to have these systems done in and hour or 2. NOPE The second year brought an employee along and the golf cart and only saved about 40 min. on the large townhome system

The large compressor was a sullair rented from the local cat dealer. The tech told me not to run it under 100psi as it needed back pressure to keep the aftercoller working properly. Well the golf course worked fine at 100psi since I installed the system with a larger compressor in mind.

I wasnt sure how the townhome systems was installed so took a chance at the pressure, so I dialed it back to 90 psi and stuck an oil pan under the machine. At a lower psi the aftercooler for the compressed air didnt work properly and bled oil. I would rather have oil bled from the machine than broken main lines in the ground.

Most system I do range from 9 zones w/5-6 rotors on them up to 30zones. So I use a 185cfm that I own. Its interesting to learn about how things are done diffrently in other parts of the country as I dont think a roofing compressor would work very efficently for us.

2 serious questions Z.

what'd you tow the 900 with? All of the 500cfms i have been around were truck mounted for ease of travel. Hauling or towing one here requires a cdl.

How do you design a system around a compressor for blowouts? I thought a design was based on hydraulics.
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[zimmatic]

I used a f350. The compressor was on a 3 axle trailer with brakes.

Installed heavier walled pvc pipe Class 200 for main line vs 160. along with multiple isolation valves.

[Wet_Boots]

160, as in PVC, or 160, as in poly?

[1idejim]

Living in the state of jefferson i had never heard of blow outs and i really don't understand them completely. I understand that there is a poc for the hose but where do you decide to connect to on a cold call? Indication of when its done? Is everything regional?

Like every other thread i have read, i should be able to tred water long enough to get a grasp.
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[cjohn2000]

Originally Posted by 1idejim

Living in the state of jefferson i had never heard of blow outs and i really don't understand them completely. I understand that there is a poc for the hose but where do you decide to connect to on a cold call? Indication of when its done? Is everything regional?

Like every other thread i have read, i should be able to tred water long enough to get a grasp.
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Depends usually I will poke around the doublecheck for an iso or a quick coupler. Other than that #4 testcock. On larger systems we cut in a nipple with a cap. As far as when its done I look for last head spewing water wait for a single puff and on to the next. Pretty easy, as well as surprising, to tell how the pipe is generally routed.

[mitchgo]

Originally Posted by cjohn2000

. As far as when its done I look for last head spewing water wait for a single puff and on to the next.

That wouldn't fly in the residential world. Typically I wait until it stops spitting water. This is all still within a general 1-3 min per zone time frame

[cjohn2000]

Originally Posted by mitchgo

That wouldn't fly in the residential world. Typically I wait until it stops spitting water. This is all still within a general 1-3 min per zone time frame

Depends on what the rest of the zone is doing. But what I mentioned is frustrating on long runs fed from one end especially when its clogged (should have been put out of its misery) bed heads on crooked riser pipes

[Mike Leary]

Originally Posted by mitchgo

That wouldn't fly in the residential world. Typically I wait until it stops spitting water. This is all still within a general 1-3 min per zone time frame

You don't want a "dry blow", a misting means "done". When I first started, my teacher taught me to burp the zones once more, but, over the years, I found no reason if the system was winterized correctly.

[cjohn2000]

Originally Posted by Mike Leary

You don't want a "dry blow", a misting means "done". When I first started, my teacher taught me to burp the zones once more, but, over the years, I found no reason if the system was winterized correctly.

Especially with water lubricated gear driven rotors. Never seen one fail after blow out.