Confused about air usage

[calvin1631]

I am confused about air usage. we were setting up a prototype pneumatic system using a 3/4" x 10" cylinder, and 4 tanks. We pumped up the tanks to 100psi and had the pressure limited to about 35psi to the cylinder. I only got it to go in and out about 9 usable times. I saw a formula to calculate this related problem and found that we should technically be able to at 120psi, with a 3/4" x 10" cylinder, have 20 actions. What am I doing wrong?

[popo308]

We calculated that at 120 psi we only could fire our cylinder out once then back in once before we had to recharge. If we fired it again yes it would work but you wouldn't have MAX psi in the cylinder so the power of it would be significantally less.

[Racer26]

Originally Posted by calvin1631

I am confused about air usage. we were setting up a prototype pneumatic system using a 3/4" x 10" cylinder, and 4 tanks. We pumped up the tanks to 100psi and had the pressure limited to about 35psi to the cylinder. I only got it to go in and out about 9 usable times. I saw a formula to calculate this related problem and found that we should technically be able to at 120psi, with a 3/4" x 10" cylinder, have 20 actions. What am I doing wrong?

I believe your calculations are shown by your experience. The 20 "actions" you calculated theoretically transfers to the actual 18 you got, 9 ins and 9 outs, if I'm understanding you correctly.

[sanddrag]

Don't forget you have hose between the solenoid and cylinder which uses up molecules of air each time the solenoid is fired.

[nickcvet89]

If you wanna increase the psi from 35 you do it through the pressure guage that comes out of the tanks, the maximum can go up to 60 psi

[Gary Dillard]

Using your number of 100 psi, 35 psi, and 10 inch stroke, I calculate 11 cycles (in and out = 1 cycle) at 35, but with 4 tanks you should still get several more at lower pressure. A few things to consider:

Not sure why you said 100 psi versus 120. The pressure switch (and the relief valve on the compressor) will cut out at 120, so if you're not getting there it seems like you may have a leak somewhere. Pressurize the system and let it sit for a few minutes to see if it bleeds down. Try it with the actuators in each position; you may be getting a leak on the side of the solenoid or piston that is not under pressure when you initially checked the system. Also, the gages are not very accurate, so you should leave some margin to account for that (and the extra air in the tubing).