Page 1 of 1
Piston Valve Maintenance Access
Posted: Sun Jul 01, 2007 7:13 pm
by Gepard
Hi,
I'd like to bounce some ideas off you guys and see what you make of this....I'm hoping to build a 250psi rated barrel sealing piston valve and the force of the piston slamming into the pilot area is obviously worrying. (That's why I started the thread about the pressure ratings of Supahs and Maulers)
What about if I welded on an endcap where you attach the pilot valve and bolted on the barrel reducer? Basically take a Mauler, and bolt on the oppsite side of the tee.
Making it all airtight etc isn't a problem, I just think that since the reducer takes hardly any force, compared whatever it is that stops the piston, it makes sense to use the weakest method of attaching it (the bolts) than the part that will get 'whacked'.
Anyone care to suggest an outcome?
Cheers,
Michael
Posted: Sun Jul 01, 2007 7:16 pm
by MrCrowley
I could see that working as long as you use a bushing and not a reducer

I don't see why it shouldn't work.
Posted: Sun Jul 01, 2007 7:20 pm
by Gepard
Sorry yeah, over here they're called reducers....
I'll blame you if it all screws up
Michael
Posted: Sun Jul 01, 2007 8:22 pm
by frankrede
Reducers generally refer to DWV I believe.
Posted: Sun Jul 01, 2007 8:51 pm
by MrCrowley
Just realised it wouldn't matter if your using metal

Posted: Mon Jul 02, 2007 6:44 am
by Gepard
Frankrede,
No this was from a company that specialises in pressure rated pipe, with pressure pipe fittings at the top of the page and 16MPa marked on the fitting itself - so I think it's safe to assume it's pressure rated
MrCrowley,
Metal fittings are much harder to come by over here though. I'll make it and see what happens.....
Michael
Posted: Mon Jul 02, 2007 7:14 am
by chaos
great idea, what metal are you making it from>>> can you weld?
-what are ya gonna use to gain that pressure?
-im interested...what is the overall gun going to be like? small/big?
cheers
~chaos
Posted: Mon Jul 02, 2007 7:45 am
by Gepard
No I meant I'll make it out of PVC and see what happens
But yes I can (and have) a welder if push comes to shove.
The gun is a stationary one, I've built a wooden frame for it that measures roughly 5ft x 5ft x 5ft with pneumatic elevation (and motorised rotation coming once I've test fired it). The actual gun itself though is based on the Scorpion Class in the Showcase except I'm making it more powerful. I've replaced the 1inch pipes with 2.5" pipes (the four chambers are 2.5 so no bottle necking anywhere) and the 1" sprinkler will be a 3" piston with 2.5 porting which will be piloted by a 1 1/2 diapragm valve piloted by a QEV piloted by a solenoid for remote firing. I'll also be doubling the pressure up to 16bar mainly 'cos I can. I'm not looking to constantly fire at 16bar but I don't like making it out of 16bar rated materials only to have a piston valve that requires 125psi or so.
Since I can program, I might write a controller interface but doubt I'll have time.
Ammo is GBs but I've got a detachable (breech loaded) barrel so can be anything.....
I'm working on how to automate the breech loading now thought I'll most likely use a double acting cylinder connected up to a set of slenoid valves...
DW, I'll be sure to post it once I'm finished.
Michael
Posted: Tue Jul 03, 2007 2:01 am
by clide
Yep, should work fine. Someone on the Spudtech forums made one like that and I've been wanting to for awhile.
It will experience the same force from pressure, but it won't have the piston slamming into it, which has always turned me off from making bolt-in plugs for piston valves. Threaded plugs would work too, but it is harder to make them compact, so I think bolting in the front bushing is the way to go if you need a compact valve.
Also, we typically use PVC well below the pressure rating (I stick to half of pressure rating) because it is not rated for air usage. Pressurized air in PVC is enormously more dangerous than water, so it's a good idea to add in some extra safety factor.