Sprinkler line winterizing... - Page 3

 


All you need for connection is a male air hose quick connect
fitting.   That you should be able to find at any auto parts store,
HD, or online.   Harbor Freight Tools has them cheap.    The fitting
has male pipe threads, generally 3/8" on the other end so you just use
whatever pvc plumbing parts necessary to make up either a permanent or
temporary fitting that you can connect to your system at the
appropriate spot.   I added a permanent one together with a ball valve
to my system.

Whether you can successfully blow out the system with a small
compressor is a different story.   I do mine easily with an old Sears
shop compressor,that has babye a 15 gallon tank and does 9 CFM at
40psi.   I let the tank get up to about 80psi, then turn on a
zone.     I only have 3 rotors per zone and 7 zones so it works OK.
Used it one year on a friends house that had 10 zones, from 6 to 10
heads per zone.    That was much more difficult and took a very long
time because these smaller compressors can't deliver the air volume to
do it effectively and quickly.    The pros use large gas powered
compressors that can blow out several zones at once in a couple
minutes.

 

Chris Tidio wrote:
 

I've got a 7-zone sprinkler system at a small commercial office
building.  Each zone has about 6 or 7 heads.  Each time the system comes
on in the summer, every head in each zone belches air for about 15
seconds before water starts shooting out of them.  This doesn't just
happen the very first time the system comes on for the season - it
happens every time the system comes on.

I'm thinking that the heads or the lines have an automatic drain
function that always kicks in when the system turns off, and therefore I
don't need to blow the lines out in the fall.

Comments?

 


You are most likely correct.  A well designed system has no need for
compressed air. I live in Denver, and used to design and sell the parts for
irrigation systems.  We always tried to design for gravity drainage of the
system.  The common  pipe for laterals here is polyethylene (poly) pipe.  It
can take a lot of water frozen inside of it, as long as the pipe is not
completely full of water.  One office building I had, the north zone in the
shade sometimes still had ice in the pipe when we would turn the system on.
It would melt out with no damage.  That system was in use for well over
twenty years, until the highway department widened the road, and dug it out.
The sprinkler guys love to convince you that compressed air is required to
keep from freezing damage.  My current home has a very old system, but it
does gravity drain.

Dale

 



Sounds like a 'positive drain" at the end of a zone. Under pressure
the valve will close and when the water pressure is off it opens and
drains the zone of water.

Sand (pit) is used  and promotes drainage at the location of the valve
(underground).

 

Although it's too late for a lot of you that have already bought
compressors ...

You would have been better off buying just a small, portable air tank (5
or 10 gallons) and rig it up with the appropriate gate-valve and
connectors to attach to your sprinkler plumbing.

http://z.about.com/d/homerepair/1/0/h/4/-/-/carry_tank_5gal.jpg

http://ep.yimg.com/ca/I/sjdiscounttools_2079_34448523

To fill the tank, either take it to a service station or buy a small
electric compressor.

I rigged up a 5 gallon tank so that I have a medium-sized electric
compressor connected to the tank as well as having the tank connected to
the sprinker system at the same time.  This minimizes the time it takes
to disconnect / reconnect the tank to recharge it.

http://www.grainger.com/Grainger/items/1VAP3

What you need to purge a sprinker line is a massive blast of
high-pressure air - which some of you now realize comes mainly from
having a large tank that's been pre-charged.  And only turn on 1 zone at
a time when you do it.

And you need a low-restriction gate or ball valve to let the air out of
the tank and into the line with as little restriction as possible.

If you connect a low-capacity / low-volume air compressor to your system
and find that you can't exceed a pressure of 30 psi then your sprinkler
system is probably self-draining and the air is bleeding out the drain.
You need more than 50 psi to force the heads up.