One way valves

[Doc543]

Are one way valves allowed on the robot? I want to have a piston to open fast but close slowly.

[Jon Stratis]

[R71]
The only pneumatic system items permitted on 2012 FRC Robots include the items listed below.
A. Items listed in the 2012 KOP Checklist or available via FIRST Choice.
B. Pneumatic pressure vent plug valves functionally equivalent to those provided in the KOP.
C. Solenoid valves with a maximum ? in. NPT port diameter, and a maximum Cv of 0.32 (if non-KOP valves
are used, the team will be required to provide part documentation validating that the valves meet these
constraints).
D. Solenoid valves that are rated for a maximum working pressure that is less than 125 psi rating mandated
above are permitted, however if employed, an additional pressure relief valve must be added to the low
pressure side of the main regulator. The additional relief valve must be set to a lower pressure than the
maximum pressure rating for the solenoid valve.
E. Additional pneumatic tubing, with a maximum 0.160 in inside diameter, functionally equivalent to that
provided in the KOP, with the pressure rating clearly factory-printed on the exterior of the tubing or with
supplier documentation showing the pressure rating.
F. Pressure transducers, pressure gauges, and connecting fittings,
G. Pressure regulators with a maximum bypass pressure of no more than 60 psi,
H. Pneumatic cylinders,
I. Pneumatic storage tanks, and
J. Compressors compliant with Rule [R73].

That's the best (and only!) list of allowed pneumatic components you'll find!

[Mark McLeod]

A flow control connector will do what you ask.

It has an adjustable flow control that affects one direction, but not the other.

Here's a thread discussing them.

[Doc543]

I didn't know they made one way flow control valves, that would be perfect

*edit

are the ones that we get in the KOP one way?

[Mark McLeod]

They usually are.
Look on the side and there should be a large arrow indicating unrestricted flow in one direction and a smaller arrow meaning restricted flow in the other direction.

[Kevin Thorp]

This is the pneumatic symbol for a flow control valve.

Picture your solenoid valve above it and your cylinder below it. Air flows in freely through the check valve on the right, but when the solenoid valve shifts and the the air tries to exit the cylinder, the check valve stops it, forcing the air through the adjustable needle valve on the left.

Cylinders typically have a flow control (A.K.A. speed control) valve on each port; one controls the extension speeds and the other controls retraction.

They're great for reducing damage to robots and fingers!