Calibration of secondary relief valve

[FrankJ]

No I am talking about the secondary relief valve pressure. It has to be over 60psi & under the max working pressure of the solenoid valve. But you have to temporally turn up the working pressure to set it.

You only need it if the working pressure of the solenoid valves is <125 psi

[Mark McLeod]

You can also just connect it temporarily to the high side while you calibrate it.

[Al Skierkiewicz]

Karlis,
This is an area of particular confusion. There is a difference between max operating pressure and recommended operating pressure. This is a case where manufacturers have maybe listened too hard to their marketing department. If the manufacture states a recommended operating pressure of 30-125 psi, that is not the max operating pressure. Your solenoids may meet FRC rules without the need for the secondary relief valve.

[FrankJ]

Our valves list a nominal operating pressure of 20-115 psi. Nominal as I define it mean working. They work fine at 125 PSI. Proof pressure is like 225 PSI. Since I can't find anything else written I am thinking I need the secondary relief valve

[kmusa]

Originally Posted by Al Skierkiewicz

Karlis,
This is an area of particular confusion. There is a difference between max operating pressure and recommended operating pressure. This is a case where manufacturers have maybe listened too hard to their marketing department. If the manufacture states a recommended operating pressure of 30-125 psi, that is not the max operating pressure. Your solenoids may meet FRC rules without the need for the secondary relief valve.

True. Unfortunately, the manufacturers often use operating, maximum, and/or proof pressures, and FIRST wants max working pressure (and (from Q&A) specifically excludes proof pressure as a substitute.)

In our case, STC's 4V110-1/8, with "operating pressure" of 21 to 115 PSI, and "maximum pressure" of 180 PSI (@75 Deg F).

Setting the relief valve to 100 PSI is probably the best approach (since the regulator should release anything above 60 (or whatever the current set point is.))

On the other hand, having the low pressure side at 100 PSI for the test can be a little exciting, when making sure that nothing is inadvertently activated, and the robot is disabled once the compressor cuts out. Next time, we'll just plug the output of the regulator.

Did discover some tired fittings in the process.

-Karlis

[Al Skierkiewicz]

Frank and Karlis,
When I see the specification "working pressure" and it displays a range, I think that the manufacture is telling me that all operations and life cycles will be warranted under those conditions. I don't believe that the spec is a max pressure at which the valve fails to operate. This is not burst pressure. I suspect that the rule is written so that teams use components that will operate as expected should the system go over expected pressures. For instance, if a valve is holding an assembly up, I would not want the valve to suddenly bypass pressure and release the mechanism. Can you contact the manufacturer and show them the rule and how their valve is interpreted under that definition?

[FrankJ]

Yeah the only other thing they will give is proof pressure. I imagine liability issues and such. Anyway the secondary valve is easy & no question during inspection.

We were running the catapult latch valve on the high pressure side with no issues. (don't worry it will be where is supposed to be for competition.)