Hello!
We need to order some solenoids and we were thinking about this one (solenoid A), but I noticed that under R84 C, solenoid A might not not be legal due to the 1/4 NPT inlet and outlets. We found another solenoid (solenoid B),, with 1/8 NPT inlet and outlets.
Is one (or are both) of these solenoids FRC legal?
The first solenoid is not legal for exactly the reason you said. The 1/4" NPT ports are larger than the maximum allowed 1/8" NPT.
From what I see in a quick look-over, the second solenoids look like they should be legal. This advice is worth what you paid for it though, so you’ll want to go over the solenoid specs and pneumatics rules with a fine tooth comb.
Has to be 1/8 NPT.
I agree that the second solenoid you linked looks legal - 215 psi proof pressure, 1/8" NPT ports. Note that it is a 24V solenoid valve, so you will have to move the jumper on your PCM from the default location. If you mix 12V and 24V solenoid valves on your robot, you will need two PCMs (or relays).
Or smaller
Does the relay port on roborio work to control solenoids?
You don’t technically NEED to use the PCM, but you should.
Yes, but indirectly. You must use a legal relay module, either the spike or an automation direct relay. Up to 8 independent sets of solenoids may be operated through the four relay ports. This is a poor option for most teams, as each relay module must be on a separate PDP breaker per R59.
For posterity, I figured I should wrap this up.
We just figured out that solenoid B (in the first post) does not actually have ventilation holes, so once it is activated, the pressure stays in and a cylinder cannot be actuated the other direction and needs manual ventilation (read: disconnect the tube to depressurize). We did some more research and found that this solenoid has the ventilation holes that we need. Hope this helps anyone who stumbles on this thread in the future.
A 3/2 way valve would be appropriate for a single-acting cylinder, or one that is actuated pneumatically in one direction, but returns to its original state with a spring or some other such mechanism.
This page seems to do a decent job explaining why in more detail, and generally how switching the ports on these solenoid valves actuate cylinders.
Benjamin, you’ve left misinformation for the future.
The AVS-3211-24D “solenoid B” operates according to diagram A from the product spec sheet and we are using these without any issues. Port P connects to your working pressure, port A connects to a spring return pneumatic, and port R is the exhaust.
Ah! I didn’t know that. Thanks for clearing it up.
Many of the solenoid valves used in FRC are actually pilot operated. it not obvious unless you read the spec carefully. On those valves it is important the pressure is connected to the P port.
R84
C. Solenoid valves with a maximum â…› in. (nominal, ~3 mm) NPT, BSPP, or BSPT port diameter or integrated quick connect ÂĽ in.(nominal, ~6mm) outside diameter tubing connection,
Frank,
As far as I’m aware, all of the commonly used solenoid valves in FRC are pilot-operated. These internally supply the necessary pilot pressure by some sort of diversion from port 1/P. Other valves can be purchased that need to be supplied with an additional source of pilot pressure, but they do utilize pilot pressure to switch positions too, and I have not really seen these in FRC.
I’m fairly new to the fluid power industry/FRC pneumatics, so it is certainly possible there are offerings I’m not aware of in use, but the options sold by AndyMark and VEXPro utilize electrically actuated pilot valves, and I suspect unless a team is doing something truly unique with different sources, their valves will too.
Josh
Actually they are quite a few that do not. Admittedly not common in FRC. They do have the disadvantage of either lower flows and/or higher solenoid load, but they are legal to use.
I realize I was a bit ambiguous, but I am aware, generally, of other valves that do not operate with some sort of pilot function. I was more curious if you had seen them applied in FRC. Like I said, I’m still very new to fluid power and FRC pneumatics in general, but I’m always curious to hear about unique applications.
I see them occasionally when inspecting robots. They where more common when the rules restricted Cv & required 120(5?) PSI working pressure. Most of the pilot operated valves are not rated that high. The MAC valves we used at the time were direct.