SpudFiles

ok so i just finished modding my sprinkler valve to use a blowgun pilot valve. The sprinkler valve is being modded for my new 1.5 inch coaxial piston gun with a piston made from a 1 inch pvc endcap. Anyways the mod went great in my opinion atleast...i mean i think i did a pretty good job tapping new threads for one of my first thread tapping jobs.
But my problem is when i first pressurized my cannon i had few leaks here and there but those were quickly fixed with the addition of more teflon tape...but for some strange reason my sprinkler valve only wants to seal part way and still let a good bit of air leak out of the back...(not where i tapped the new threads those are holding up great)
So from any of you more exsperianced spudders out there any suggestions?

my guess is that its just not enough pressure moving through the valve quick enough to make the seal... but i dont know...i was late when i finally had a chance to pressure test my gun i will run more tests tommorow and give you guys an update
PS this my first post but not first piston cannon...this about my 5th piston cannon...and about my 8th cannon overall... im not a total noob...lets just say i know my way around a hardware stores plumbing section
Any help/suggestion are appreciated thanks!

there might be some dirt on the seat of the valve and its leaking past it, open it up and give it a good clean.

I had this exact same problem. The issue was that a small amount of air was getting through the old solenoid valve chamber. I fixed I by pouring more epoxy into the solenoid port.

It sounds like you're not filling it fast enough to seat the diaphragm. It looks like you are using a compressor, so you might can try moving the fill valve to the sprinkler valve pilot area.

Also, double check to make sure all leaks are fixed. I've modded a whole bunch of sprinkler valves and I still can't seem to get the threads in the cap straight. Epoxy is liquid duct tape and will be your friend in this. Be sure to check the hose and blowgun valve as well.

How is the equalization hole in the diaphragm? Was it modified any? If you left the little filter on it, it may be hindering the flow, and preventing the pilot area to fill quickly enough.

Check the Hubb Library for The Sprinkler Valve. Lots of good info and has a troubleshooting guide that you might find helpful.

To Hubb,
yes your right i am using a compressor, nothing else on the entire gun is leaking except for the valve, and yes i did pull the little filter in the diaphrams equilization hole out and it still leaked so i put back in and it continued to leak, and i also filled all the holes that needed to be filled with a plastic bonding glue, and it is holding perfectly

for now i just went back to using the solenoid to fire it and it seems to work pretty good...but i would like to get the pneumatic trigger working...so i dont need to freakin plug my gun in lol

lastly i have a question about powering my solenoid..it came with a 24 volt 300 ma output charger but i want to somehow battery power so i dont have to run out an extention cord to fire my gun...any suggestions?

A sprinkler valve works fine on 12-18 volts DC. A pair of 9V or 7.2 volt RC batteries in series works.

thanks technician,
ya thats what i was thinkin to just rigg up to 9 volts or rc car batteries together...but what about the amps...are there enough supplied by the 9 volt or the rc car battery for the valve because the wall inverter that it originally came with is 300 ma

http://www.spudfiles.com/spud_wiki/inde ... kler_valve

Most will work fine on a single 9V. 3 is not needed.

the valve is rated for 24 volts though so wouldnt only 9 volts be a bit underpowered?

Not really. AC inductance limits the current on AC. On DC only resistance of the coil wire limits current. Magnetism is directly related to the current, not the voltage. Most 24VAC solenoids draw higher current on 12 VDC than they do on 24 VAC.

I used a meter and measured the current on one with DC and AC.
See this thread.
http://www.spudfiles.com/forums/questio ... 18083.html

Due to the inductance change as the valve core pulls into the coil, on AC higher current is drawn until the core pulls in, then drops to a lower value. On DC, you need to have the pull in current to open the valve, not the hold current value which is what I measured. The hold in current is reached at about 6 VDC.

This is probably more technical than you care for, but it works in theory and in reality.

Well, you have the valve on the right way (I thought I messed up my first modded valve because it wouldn't seal, but it turned out I just had it on backwards)

In addition to what has been said by others, you could make sure that you tightened the screws enough when you put the valve back together.