syringes for valves

[Anatine Duo]

Initially I was thinking of using one to pilot a coax (mechanically hold in place; release sear to let syringe head out of the pilot tube), but it dawned on me they could be adapted for other spud purposes too. JSR had some inspiring designs using them.

I recall reading somewhere that some single stroke pneumatics don't hold full pressure because of soft rubber in the pump head not holding air. If that's true it might also be true that the soft material in a syringe head won't hold pressure for long. Anyone have any experience in this matter before I start casting epoxy reinforcement?

I like to see a pneumatic hold pressure overnight... in case zombies attack first thing in the morning.

[farcticox1]

That could happen

[hectmarr]

Initially I was thinking of using one to pilot a coax (mechanically hold in place; release sear to let syringe head out of the pilot tube), but it dawned on me they could be adapted for other spud purposes too. JSR had some inspiring designs using them.

I recall reading somewhere that some single stroke pneumatics don't hold full pressure because of soft rubber in the pump head not holding air. If that's true it might also be true that the soft material in a syringe head won't hold pressure for long. Anyone have any experience in this matter before I start casting epoxy reinforcement?

I like to see a pneumatic hold pressure overnight... in case zombies attack first thing in the morning.

I have used and still use syringes to make pneumatic test valves of all kinds. The longest time I have had a syringe with compressed air is about 10 minutes and I have not noticed that it loses pressure. If the time increases, this is likely to happen, but only a test with a syringe will answer your question safely.

[jackssmirkingrevenge]

Before I had the facility to machine o-ring pistons, syringes were always my go-to for 100% seals.

If that's true it might also be true that the soft material in a syringe head won't hold pressure for long

I don't think this is the case with syringes - essentially the pressure forces the material to expand again the walls of the cylinder, making it seal even better. What pressures did you have in mind?

[Anatine Duo]

300ish psi

The whole concept is a little odd... I feel rubber either holds air or it doesn't. Soft rubber inner tubes hold air... balloons do pretty well for a day or two. Worst case scenario I can put an o-ringed job into the syringe if the syringe head starts leaking.

I only have one single stroke pneumatic. I guess I could Chrony that after leaving it a day, though it will be weird leaving it actually loaded (I don't think I can open it for loading without retracting the pump head).

[jackssmirkingrevenge]

I don't think you can compare the two, pumpers typically have a parachute seal which isn't the same thing as the rubber plug that a syringe represents.

If you're not comfortable with syringes, there are options for the lathe deprived:

http://www.spudfiles.com/how-to-databas ... 21740.html