I picked up an old 1 hp comp (cast iron pump, twin "hotdog" tanks, a
real Dayton 1725 rpm, 1hp motor) several years ago. This compressor
used pneumatic actuated valves on the compressor - motor ran
continiously. I changed it over to a conventional pressure
regulator / check valve / pop off valve. I bought the check valve
(w/ unloader port) at Grainer:
http://www.grainger.com/Grainger/CDI...781?Pid=search
.. After about 25 on/off cycles the valve sticks open when the
compressor is not running - air escaping thru the unloader valve - so
the compressor now cycles on once every min to 90 sec with a compress
time of (guessing) 20-25 sec. when there is no air usage. I whacked
at the valve with a 3/4 inch bar stock - no hammer close by and with
each whack the air flow reduced. After about 3 or 4 whacks the air
leakage was gone and the comp opperated correctly during cycling - for
a while and then it started loosing air at the unloader valve.

I'm working on reroofing a house this weekend and I can't keep on
running down the ladder every time the valve sticks. I also do not
want to leave one of my other (better) compressors outside in the
backyard of the house that I'm working on. I'm tempted to open the
valve up - it looks like the check valve parts are inserted from the
side that has the large hex. So, what is inside of a check valve -
tiny loose parts that will spring out at me and get lost? Right now
its a pain in the ass, but if I take the valve apart and can't get it
to work it will be a much bigger pain to be with out a compressor.

aribert n wrote:


. After about 25 on/off cycles the valve sticks open when the
compressor is not running - air escaping thru the unloader valve - so
the compressor now cycles on once every min to 90 sec with a compress
So, what is inside of a check valve -
snip
tiny loose parts that will spring out at me and get lost? Right now
its a pain in the ass, but if I take the valve apart and can't get it
to work it will be a much bigger pain to be with out a compressor.
You can probably get a replacement valve at someplace that sells
air tools. Not Lowe's, but there ought to be someplace open on Saturday.

Jon

"aribert n" wrote in message
...
I picked up an old 1 hp comp (cast iron pump, twin "hotdog" tanks, a
real Dayton 1725 rpm, 1hp motor) several years ago. This compressor
used pneumatic actuated valves on the compressor - motor ran
continiously. I changed it over to a conventional pressure
regulator / check valve / pop off valve. I bought the check valve
(w/ unloader port) at Grainer:
http://www.grainger.com/Grainger/CDI...781?Pid=search
. After about 25 on/off cycles the valve sticks open when the
compressor is not running - air escaping thru the unloader valve - so
the compressor now cycles on once every min to 90 sec with a compress
time of (guessing) 20-25 sec. when there is no air usage. I whacked
at the valve with a 3/4 inch bar stock - no hammer close by and with
each whack the air flow reduced. After about 3 or 4 whacks the air
leakage was gone and the comp opperated correctly during cycling - for
a while and then it started loosing air at the unloader valve.

I'm working on reroofing a house this weekend and I can't keep on
running down the ladder every time the valve sticks. I also do not
want to leave one of my other (better) compressors outside in the
backyard of the house that I'm working on. I'm tempted to open the
valve up - it looks like the check valve parts are inserted from the
side that has the large hex. So, what is inside of a check valve -
tiny loose parts that will spring out at me and get lost? Right now
its a pain in the ass, but if I take the valve apart and can't get it
to work it will be a much bigger pain to be with out a compressor.

They are all a bit different but usually they can be cleaned without having
to fully disassemble

Remove and clean it by soaking in soapy water and/ or alcohol,
re-install....

In my experience, synthetic oils tend to clog air valves and so forth worse
than a straight non-detergent oil will and so if the compressor has
synthetic oil in it you might to replace.

On May 25, 11:15*pm, aribert n wrote:
I picked up an old 1 hp comp (cast iron pump, twin "hotdog" tanks, a
real Dayton 1725 rpm, 1hp motor) several years ago. *This compressor
used pneumatic actuated valves on the compressor - motor ran
continiously. *I changed it over to a conventional pressure
regulator / check valve / *pop off valve. *I bought the check valve
(w/ unloader port) at Grainer:http://www.grainger.com/Grainger/CDI...r-Check-Valve-...
. *After about 25 on/off cycles the valve sticks open when the
compressor is not running - air escaping thru the unloader valve - so
the compressor now cycles on once every min to 90 sec with a compress
time of (guessing) 20-25 sec. when there is no air usage. * I whacked
at the valve with a 3/4 inch bar stock - no hammer close by and with
each whack the air flow reduced. *After about 3 or 4 whacks the air
leakage was gone and the comp opperated correctly during cycling - for
a while and then it started loosing air at the unloader valve.

I'm working on reroofing a house this weekend and I can't keep on
running down the ladder every time the valve sticks. *I also do not
want to leave one of my other (better) compressors outside in the
backyard of the house that I'm working on. *I'm tempted to open the
valve up - it looks like the check valve parts are inserted from the
side that has the large hex. *So, what is inside of a check valve -
tiny loose parts that will spring out at me and get lost? * Right now
its a pain in the ass, but if I take the valve apart and can't get it
to work it will be a much bigger pain to be with out a compressor.

The unloader is there to protect the motor from drawing excessive
current. I know that it's heretical, but I've run small compressors
with the unloader plugged and I had no problems. If you're in a
pinch, that's what I'd do.

On Sat, 26 May 2012 08:33:55 -0400, BQ340 wrote:

On 5/26/2012 12:15 AM, aribert n wrote:

--snip--

So, what is inside of a check valve -
tiny loose parts that will spring out at me and get lost? Right now
its a pain in the ass, but if I take the valve apart and can't get it
to work it will be a much bigger pain to be with out a compressor.

I have the same valve on my compressor, under the cap on the side is
just a plastic disk & a spring.

I'll wager the spring broke, a quick fix is just the stretch out the
larger remaining piece of the spring & re-assemble until you can get
another spring.

MikeB

Mine's a ball (metal, marble sized) and a spring about 3/8" in diameter;
for some unknown reason some previous owner had removed the ball.

If you lose either part you're toast, so don't try the disassembly over
grass.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

Just a quick follow-up. I took the check valve apart numerous times
to clean with no improvement - it was a simple disc with a very light
spring. I stretched the spring to provide some additional force - that
just made the poppet have a non parallel relationship to the valve
seat. I tried to use a heavier compression spring but I was unable to
get the poppet to seat what so ever.

I called CDI on Tuesday and received a call back on Wednesday from an
individual in their engineering dept. I had selected a check valve
that was inapproproate for my application. Apparently not all check
valves use the back side pressure to augment the spring to seat the
valve. I was quite pleased in getting a response from CDI (even if
it did not solve my immediate issue). Short term, I ended up
plugging up the unloader port and lowering the cut in pressure by
about 10 psi - no more tripped breakers (1hp straining to start
rotating on a 20A circuit).