[Chris Fultz]

In my opinion, the system probably safely operate above 60 psi. The presssure between the tank and the first regulator valve is 120 psi, and we use similar components (especially the tubing) through-out. The 60 psi limit is probably both to add a safety factor in the system (a blown hose or other component could seriously injure a student) as well as put a limit on the power of the pneumatics. Remember the commetns from the kick-off - don't turn into a lawyer. Your goal should be to keep the system under 60 psi and it can be done just by reducing your regulated pressure.

Operating through the exhaust like you are is probably not significant, but I thought it should be mentioned. One difference in this design circuit vs. running into a wall is that running into the wall is unintentional, but building the pneumatic circuit is intentional.

I had three reasons for the post - one is that I laid out the schematic and it looks like it would work and I think it is great that studetns have found a way to do this, another was to clarify / correct a few statements about pressures and forces to be sure others walked away with the right concepts, and the third was just to be sure students were aware that part of the system had to be over 60 psi to make this work (if the system regulator was set at 60).

Please post any info you get from FIRST. And good luck in fluids.