Issues with vacuum and solenoid interaction

Hi, We are trying to use a low pressure aquarium pump to quickly attach and release suction cups.

Our interpretation of the topmost solenoid schematics is that when 14 is active then 5 is blocked, air flows from 1 to 4 and there is flow from both 3 to 2 and 2 to 3. We believe that the opposite is true for when 12 is active.

In the indicated setup (lower) our thought was that when 14 is activated exhaust would flow through 3 to 2 and vent through there while the vacuum would continue through 1 to the suction cups, resulting in the suction cups sticking to the surface. When 12 was activated, we thought that the vacuum would switch from connecting to port 4 to port 2, and the exhaust would go into the suction cups, meaning they would release. However, in this orientation the suction cups would constantly be in exhaust. The opposite was true when the two initial tubes were switched: the suction cups would only be in vacuum.

Is there some configuration of this solenoid, (or multiple) where a single port switches between suction and exhaust? Otherwise, is there a different solenoid that we could use?

You mean suction and exhaust?

FWIW we had suction and exhaust to atmosphere in 2019

Thanks, fixed typo. The issue with using atmosphere in this case is that it will take ~5 seconds before the object will be released. While it is an option, our hope is that there was some faster way.

If you have to “backdrive” the suction cups (or other parts of the system) with positive pressure air you are going to have to prove that every part of that system meets the pneumatic component rules regarding pressure ratings. In particular R802 (page 106) and R804 (page 107). If the back side of that pump generates ANY positive pressure that you are not immediately venting to the atmosphere it MUST comply with R806(page 108). Please make sure you are in compliance for the whole subsystem.

Keep in mind that solenoid valves generally need a minimum priming pressure at the “inlet” port (number 1 in your diagram). I’m not sure how that would work in a vacuum

Most of the pneumatic valves used in FRC are air piloted. What that means is that the solenoid portion of the valve opens up a very small port and the air pressure in that circuit is what moves the valve. With no air pressure they will not change state and with vacuum, if it does anything, it is likely to do the opposite of what is commanded.

You are correct in how it functions, at least when provided with pressure.

This topic was automatically closed 365 days after the last reply. New replies are no longer allowed.