need help (air valves)

MR. CSM ENGINEER

thank you for the great answer,and yes i have one more question,is it possible to put an air timer between an air valve and an air cylinder also what type of pressure do i need to activate a valve or cylinder THANK YOU SO MUCH FOR YOUR HELP.

It is certainly possible to insert an air timer between a valve and a cylinder. Of course, the timer will only run when the valve is "on". The second part of your question opens up some other principles. Let me address the cylinder first. The pressure required to operate a cylinder is (mostly) dependant on the diameter of the cylinder and the load it's moving. Simply take your force per unit area (psi for example) of the air supply and multiply by the area of the cylinder piston (square inches) to get the force that will be exerted (pounds). Remember that air cylinders "push" (extend) harder than they "pull" (retract), because the rod diameter reduces some of the piston area. There are some very specialized (read "expensive") cylinders that compensate for this difference. Also remember that your air supply will determine the speed of the cylinder; you will have to calculate how long it will take to fill the cylinder to determine the rod speed. As for the valve, I'm not sure what you're asking. If you're asking about air pressures that a valve will hold, they're available in any pressure range you can imagine. If you're asking about an air-piloted valve (opens upon application of a pneumatically-based signal, not the air supply, like a relay) what you're asking about is called crack pressure. Again, these are available in many ranges, but your local supplier should be able to help in detail. I have had manually-operated valves in mind through this discussion, but this all applies to automatic valves as well. There are also electrically-operated valves (commonly referred to as solenoid valves) available that operate on a wide range of voltages, both AC and DC.

Next question!

(Out of curiosity, what are you building?)

Selection of the correct configuration depends on what is needed to happen on the plant in the event of air failure. It follows from what is drawn on the 'for construction' P&I Diagram, as an output document from a HazOp Study. The different configurations are denoted by different symbols on the best diagrams.

• If the valve has to stay in its last position, use a double-acting actuator.
• If the valve has to fail shut, use an air-to-open, spring-closed actuator.
• If the valve has to fail open, use an air-to-close, spring open actuator.

A single-acting valve could be described as air-one-way, spring the other. Single-acting actuators will typically have one air line only.

A double-acting valve could be described as air-one-way, air-the-other. This actuator will typically have 2 air lines to it.

As an example, Worcester ball valves are readily fitted with Norbro single-acting actuators (usual disclaimer). By removing the actuator from the valve, one can see a U-shaped insert in the square socket on the underside of the actuator; removing the insert, replacing it 90° differently and reassembling the actuator to the valve is all that is required to change the assembly from air-to-open from air-to-close. It can be done on the bench readily using an adjustable wrench and a pair of snipe-nosed pliers, typically in about 10 minutes.

Valve distributors will assemble valves and actuators configured ready for use in response to the correctly specified information when ordering.

what is the differance between a single acting valve and a double acting vavle

single acting = Let Air in to go forward. Let Air out to go back.= Spring-loaded

Double acting

• back of piston gets pressure air,front open to atmosphere=PUSH
• back of piston opened to atmosphere,front gets pressure air=PULL

<must air be released >

Must

Why don't you describe what you want to do and then there are several of us that can help you with the proper components you would need to accomplish with what you want to do.

I have over 30 years of Fluid Power Design experience and I know of others on CR4 that have more experience than me.