issues with Solenoid(Valve)

[team1631]

Last week we had a perfect setup for our bot. Everything worked fine. We could shoot the ball and the such. Our president made the decision to up our valve from a 12v to a 24v. We did it, and suddenly it didnt work. We set it up all right, we put it through the 24v on the power board and all. But it just wouldnt work. Finally after a day or two we decided to go back to our 12v, and found that it wouldnt work as well. We have NO clue as to why. All of us have little experience with this issue and with pneumatics in general. The solenoids are receiving power but the valve isnt turning on or off.

[Nirvash]

Originally Posted by team1631

Last week we had a perfect setup for our bot. Everything worked fine. We could shoot the ball and the such. Our president made the decision to up our valve from a 12v to a 24v. We did it, and suddenly it didnt work. We set it up all right, we put it through the 24v on the power board and all. But it just wouldnt work. Finally after a day or two we decided to go back to our 12v, and found that it wouldnt work as well. We have NO clue as to why. All of us have little experience with this issue and with pneumatics in general. The solenoids are receiving power but the valve isnt turning on or off.

Is the system pressurized while you are testing the valves? The valves we use generally have a minimum PSI needed to switch, this includes the outputs of valve. If an output is venting to the room, the valve will not switch.

Also, how did you verify that the valve was receiving power?

[team1631]

We used a voltage meter to check if it was receiving anything. Pressurizing is kinda hard to do when the valve starts open.

[Nirvash]

Originally Posted by team1631

We used a voltage meter to check if it was receiving anything. Pressurizing is kinda hard to do when the valve starts open.

That would be your issue, the valve outputs can not be open to room air. Connect a short length of tubing to the outputs and kink it(And probably ziptie it to hold it in place), then try.

[team1631]

Thanks we are trying that out now. I'm just to clarify you said that the output venting to the room needs to be kinked so that we can switch the output that starts off?

[Nirvash]

Originally Posted by team1631

Thanks we are trying that out now. I'm just to clarify you said that the output venting to the room needs to be kinked so that we can switch the output that starts off?

Just to make sure everything is clear, I assume you are using double acting valves, which have 3 ports on one side and 2 on the other.

Like this:

Output1 Output2

Vent1 Input Vent2

The input is the obviously connects to the pressure system.
The vents have nothing connected to them.

Both outputs must be able to pressurize, a simple way to do this is to have two kinked lines on the outputs.

[Bill_B]

Originally Posted by Nirvash

...
Both outputs must be able to pressurize, a simple way to do this is to have two kinked lines on the outputs.

The kinked lines are there merely as testing for solenoid activation in the absence of an actual cylinder. Once you confirm the solenoid operation, you can remove the kinked line and eventually hitch the unkinked tubes to the cylinder(s). BTW we use a tubing T-fitting with one "input" tube and another tube that goes from one leg to the other of the T. This is effective as a stop wherever you need to plug a tube run for leak checking, etc..

[Joe Ross]

Originally Posted by team1631

Our president made the decision to up our valve from a 12v to a 24v. We did it, and suddenly it didnt work.

Electrical things rarely like switching voltages arbitrarily. Next time someone asks you to change things that are working, it might be worth asking why.

[goofy173]

I'm confused about kinking the outputs. Are we talking about Festo valves?

I've had 3 of these open and completely disassembled to clean them (There was some moisture inside for some reason, probably kids blowing in them). The small electric solenoids on each end open to pass air to transfer the pneumatic valve. I wouldn't see a reason the outlet needs to be kinked.

Furthermore when I finished cleaning the 3 of them I had, and reassembling them, all 3 operated and transferred back and forth with the outputs open to air.

As far as testing them without air first, electrically, you should hear the electric solenoid transfer. (a small click)

[Mr V]

Originally Posted by goofy173

I'm confused about kinking the outputs. Are we talking about Festo valves?

I've had 3 of these open and completely disassembled to clean them (There was some moisture inside for some reason, probably kids blowing in them). The small electric solenoids on each end open to pass air to transfer the pneumatic valve. I wouldn't see a reason the outlet needs to be kinked.

Furthermore when I finished cleaning the 3 of them I had, and reassembling them, all 3 operated and transferred back and forth with the outputs open to air.

As far as testing them without air first, electrically, you should hear the electric solenoid transfer. (a small click)

There is no need to "kink" the output hoses for the valve to switch, but there is a need for a minimum amount of pressure to be available on the input side for the valve to fully switch as many of the valves used in FRC are air piloted. So if you hook it directly to a compressor and try to make it switch the loss of air out of the side that is currently activated may be large enough so that pressure doesn't build high enough for the valve to switch.