Regulated Disco Valve

Last year I made a regulator that attaches directly to a Disco valve.... I was working on different ways to produce a non-PAL PCP (ie under 500 fps).... It did the job by using a shortened 2240 valve spring.... Here's what it looks like....

http://i378.photobucket.com/albums/o...DiscoValve.jpg

It replaces the front end of the valve, and is long enough to cover the roll-stamped area on a 22XX tube.... I used the piston and spring from a Ninja regulator, so the parts are easy to obtain, in fact I just bought a Ninja rebuild kit to get them.... The back half of the valve, including the poppet and spring, are stock....

http://i378.photobucket.com/albums/o...latorParts.jpg

I installed it into a 2260 tube for testing.... I found the velocities more consistent with a lightened hammer (I went all the way to 30 gr. - 50% of stock).... Here is the shot string....

http://i378.photobucket.com/albums/o...PAL2260PCP.jpg

It appears that the regulator setpoint with just the spring (no shims) is about 650 psi.... I was quite pleased with the flatness of the shot string, 55 shots averaging 492 fps with 14.3 gr. JSB Express pellets, and the efficiency worked out to 1.21 FPE/CI.... I also tried it with a stack of Belleville washers (disc springs), and with a setpoint of about 1350 psi it gave 10 shots averaging 773 fps (19 FPE) with an efficiency of 1.13 FPE/CI.... The limited number of shots at higher power is because of the 2000 psi fill limit.... It only left 650 psi available, which is only 168 CI (at 1 bar) with a 2260 tube.... You could double that shot count by using a Disco tube.... but in reality there is little point.... Regulators are at their best when the setpoint is low enough to utilize a much wider range of pressure.... Having said that, shimming the coil spring a bit and bringind the setpoint up to about 1000 psi should give a good shot count and velocities in the high 600s.... Adjusted the way it is would produce a non-PAL Disco with over 100 shots per fill....

Bob

So what's stopping someone from doing this with their Disco valve in their Disco? A couple people were selling custom regulators for the Discovery for like $70-80 awhile back as I seem to recall.

Nothing to prevent it.... The regullator covers the gauge hole, so you lose that.... I though the Disco regulators were closer to $100....

Bob

$100.00 may be right- all I remember is that they were a bit pricey- and also lost the gauge port.

Bob just trying to make sure I fully understand your reg setup.

Everything aft of the double O ring is at atmosphere.

The hole in the side of the spring chamber is to vent same

Main pressure is entering thru a hole in the face and travels up the stem into piston chamber

Piston moves back to seal the hole

Where is the air entering the stem? Must be through the side I can't see? can't be straight through the stem or it wouldn't seal the entrance

The spring chamber inside the regulator (and the middle of the piston, between the O-rings) is at atmosphere, but of course the inside of the (right hand) valve portion is at the regulated pressure....

I should have turned the piston so that you can see the hole better.... If you look closely, just left of the small O-ring and down, you can see the hole where the air enters the piston.... It the travels up inside the piston to the top (right side in the photo) where it enters the valve and then pushes back on the piston.... When the air pressure inside the valve is great enough to overcome the heavy sping, the piston moves (left) towards the air reservoir and the seal in the (left) end of the piston hits a seat inside the portion with the two O-rings....

HTHs....

Bob

AHA...Yes I see it now. Thanks that helps a lot

The reason I asked is I've been toying with the idea of putting a regulator in the AR