Larry Jaques writes:

On Sun, 30 Oct 2011 22:25:39 -0400, blueman wrote:
So it seems like the 1/2inch air hose and 1/4 inch fittings (at both
ends) were insufficient to supply enough pressure to maintain 55 psi
through the irrigation system. I guess this makes sense since the
irrigation system itself has 1" diameter pipes and the heads probably
let through a lot more air than the 10 gallon/minute of water that it
does when driven by water.

I'm betting on the regulator being your bottleneck. If you're running
90psi normally, the 115 shouldn't be a problem, as it won't be that
high for long.

It's a cheap regulator (Harbor freight). So if I understand you
correctly, you are suggesting that the regulator limits the volume
significantly and may be the problem here?

I was hesitant to run it higher than 60 since people always warn against
using high air pressures in pvc pipe. Is high air pressure any more
damaging (in the non pipe burst case) to irrigation control valves,
irrigation heads, and backflow preventors then an equivalent water
pressure? (I would think not but just checking)

But you are right that it won't be at that pressure long since as soon
as the irrigation valve opens, the pressure will definitely drop even
before the tank runs out just simply due to the resistance of the hose &
fittings. Actually, the compressor while rated at 115 psi, the pressure
switch shuts off closer to 100 psi.

Note: my water supply is at 90psi static and drops maybe to 80-85 with faucets
open.



So, it still had no problem clearing all the zones (one-by-one) of water
down to a slight mist. But I'm not sure the added tank made much of a
difference. Still, for ~$40, it seems like a good addition to my stem
that I can use for multiple uses in the future.

It might have been more evident at the full rate, without the
regulator. You could always fill and try it again to see.


Still, I am a bit hesitant to put that pressure in the irrigation pvc
pipe and fittings...