Finally I got around to make a gun out of a valve that I had sitting around for a long time. It´s the larger one of the tees in my avatar.
The set-up is a rather conventional 3000 cc barrel sealer, except:
- The main seal is not on the front of the piston, but rather on its seat. It´s an O-ring, about 60 mm inner dia, jammed into a groove. The piston is a 63 mm ID end cap, and the tee is 75 mm ID.
- The pilot valve is a DFTV. In fact, it´s my SEX Pistol now returned to pilot valve service.
The barrel is a 75 mm OD PP drain pipe. I am NOT afraid it will explode; that plastic is really tough, much better than PVC. Only problem is, it is nearly impossible to cement.
I have only fired the gun once since I built it (and it had been lying around for a long time before that - I am concentrating on a different project right now). It sent an orange about 50 m in a neat and straight line, before it splattered on a tree in a large cloud of vaporized orange juice
And that was at only 5 bar - I was afraid of too much recoil at higher pressures.As for higher pressures, the weakest part, the chamber pipe, is rated for 10 bar. Everything else has a 16 bar rating. My supplier only gets 16 bar pipe when he can´t get 10 bar - but then he sells it at the 10 bar price
In a few days, I will take it to 10 bar, with my friend taking a video... I got the oranges today, hehe. Stay tuned.
Regards
Soren
nice work on the large porting for that size tee. When you fire it, do you use the pilot valve as a shoulder support? or du you fire it from the hip? i would imagine that the recoil at higher pressure than 5 bar combined with an orange could do some damage to that pvc if it was to be shouldered 
