3-Position Valve Needed

[jnnewton]

I have an application where I need a pneumatic valve to have 3 states. One of the work ports would be plugged, the other would be connected to a bladder The "normal" state would have the work port open to exhaust. The other two states would switch between two different pressures. Could someone help me with the plumbing and the valve selection. I would rather not use two valves for this.

 

[kcj]

In just a quick read, could you use a normal two solenoid, 3 position, spring centered valve? I don't know what brand of pneumatic, but many hydr valves are available open center, P to T. Then, connect Work port to P, solenoid 1 A or B is to pressure one, sol 2 is to pressure 2. This does require going through neutral when changing pressures.

kcj

 

[budt]

Use a spool type 5-Way 3 position with the center condition having "1" ("P")open and "2" ("A") and "4" ("B")connected to (1)("P") to atmosphere. Connect port "3" ("E1") and "5" ("E2") to the different pressure inputs.

Connect ports "2" and "4" to the inlets of a shuttle valve and the outlet of the shuttle valve to the work.

You will probably have to plumb an external pilot supply if the valve is not direct solenoid activated. Also when you want different pressures you will pass thru the work ports open to atmosphere and lose some air in the transition.


Bud Trinkel CFPE
HYDRA-PNEU CONSULTING, INC.
fluidpower1 @ hotmail.com

http://www.fluidpower1.us