Pressure for blowouts

Discussion in 'Irrigation' started by cjohn2000, Nov 1, 2012.

  1. cjohn2000

    cjohn2000 LawnSite Senior Member
    Posts: 554

    So now its transition time, moving to a new company. I have always done blowouts with a 185cfm tow behind and 1" air hose and now I will be using a gas powered roofing compressor. I have heard that you have to run air at a higher pressure due to small orifices and low flow at low pressures. Basically using the main line as a storage tank. I have always stuck to no more than 60 for the typical resi system and no more than 80 for the comm jobs. Any experience with this? Thanks, Corey.
  2. irritation

    irritation LawnSite Gold Member
    Posts: 3,248

    You're screwed, go back.
  3. cjohn2000

    cjohn2000 LawnSite Senior Member
    Posts: 554

    Yeah not my first choice for compressors
  4. mitchgo

    mitchgo LawnSite Silver Member
    Posts: 2,780

    Transition!! Gas powered roofing compressor?

    hella high pressure with low volume.. Who are you working for now??

    It costs roughly 70-90 a day to rent a 185 compressor.. 850-950 a month.. Basically that's less then a hour to make up 1 days worth of rent or 1-2 days worth of work to make up a month.. convince your new boss it's time to do what's right

    come up to redmond with us

    Right now we have 5 compressors in the lot. ( 1 owned and 4 rented for the next month)
  5. DanaMac

    DanaMac LawnSite Fanatic
    Posts: 13,156

    Pretty sure you'll need higher than normal pressure, but not sure of the exact amount.

    Funny story. Early last week I got a call from a local TV news station that wanted to interview me on one of our sites to explain the sprinkler blow outs, and the big rush as to why everyone calls at once in the fall. I declined it due to too much work, and not enough time. I wouldn't be able to handle the excessive phone calls that might come with having a spot on TV. Later that night TomTom let me know that the station had a spot on their nightly news with a different contractor that I know. It all seemed fine, until I see who I guess is one of his employees, drag up a small construction style compressor that gets plugged in. I almost fell off the couch.

    Here's the thing - for the most part, it can be done with a small compressor. Not Mike's mega systems, but on cookie cutter type lots, it will work. BUT!!!! They take so long to do, one zone at a time, and cycling the compressor to let it build pressure back up, that you can't get enough done in a day. So you would lose out on potential customers because you would get further and further behind. With the larger compressors, even with my 100 cfm machine, I can do 2-4 zones at a time designed at about 10-15 GPM. I can't see using those itty bitty compressors on systems over 10 zones.
  6. 1idejim

    1idejim LawnSite Fanatic
    Posts: 9,441

    I can see your concerns about a TV interview, what with all the papparazzi problems on the news lately.

    Now that the public has seen how simple it is to winterize their systems, many more mow-blow/DIYer will be doing blow-outs.
    Posted via Mobile Device
  7. DanaMac

    DanaMac LawnSite Fanatic
    Posts: 13,156

    It's not so much the paparazzi I worry about, as it is the single moms :)
    It was just the wrong time. I would have enjoyed doing it if it wasn't a last minute thing. I would prefer to do an interview in the spring on making systems more efficient and how to deal with water restrictions and record temps.

    You would be amazed at all the jackals on craigslist advertising blow outs for $25-$40. At least the guy doing the tv interview said the average was $60.
  8. cjohn2000

    cjohn2000 LawnSite Senior Member
    Posts: 554

    Make sure and remind the DIYers the more pressure the better :laugh:

    At least the roofing compressor has a built in regulator. This year so far I have had a coworker to run the regulator piece we use.
  9. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 47,715

    If you don't set the regulator over 70 psi, you should avoid damage. (Orbit heads blowing apart don't count)
  10. Mike Leary

    Mike Leary LawnSite Fanatic
    Posts: 21,982

    The reason the rental shop gave us such a good deal on our 125, was we dialed-it down to 70 psi for smaller blow-outs and the crew forgot to adjust it back to max when it was returned. The next guy usually returned the compressor, complaining. :dizzy:

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