Rubber for pressure switch membranes?

At work we have some pressure switches that activate at low pressure, maybe less than 1PSI, and have high pressure of over 400PSI in cycle. (safety switches to prevent presses from opening while pressurized) They have a thin rubber membrane as you describe and a thin piece of stainless steel. The stainless steel sheet (Maybe 1/4mm thick) keeps the rubber from bulging out of shape with over 400 PSI on the line. Maybe if you could fit it you could use thin SS with your rubber, rubber for the seal and SS for strength.

RogerN

Without knowing the Durometer hardness and whether the original diaphram has reinforcing fibers, it's going to be a cut and try. A pressure switch is like $20 from the local hardware, so, for me at least, it's not worth messing around with it. Only if the switch was the last of its type would it be worth it. Or if it were a multi- hundred dollar component.

Stan

Hey, I have a slightly related problem. I need a soft, pliable material to rebuild a fuel pump I made for my tractor. It needs to tolerate exposure to gasoline, the main problem I have. I bought some gasoline diaphragm material from McMaster, I think, and it lasted for literally 10 minutes! I had been using some miscellaneous rubber sheet material and it would last for up to

2 years, but has finally gotten crumbly. So, now I need some new "stuff" to make another diaphragm. The stuff they used to have in carburetor accelerator pumps would be ideal, it was thin and quite flexible, and obviously withstood gas and flexing for years. Anybody know where to get such stuff? I need about a 2" square of the stuff.

Thanks,

Jon

Jon, I suppose you already know that neoprene is needed for gasoline contact, unless the new fuel formulas attack it, otherwise, I don't know of any newer product that replaces neoprene.

For a diaphram, the best product will most likely be a fabric reinforced sheet, to withstand all the flexing and some pressure.

There are a lot more products made of neoprene these days, including hip waders and rugged severe weather garmets.

I think searching for a fabric reinforced neoprene will yield more durable products, although some old car restoration vendors may have the correct materials for rebuilding old fuel pumps.

I bought some stuff from McMaster-Carr, it was supposed to be reinforced neoprene. It was really stiff with the reinforcing, and then the stuff just disintegrated between the weave in a very short time. I suppose the stuff could have been mismarked, and not what I ordered.

Yeah, that's what I need. Maybe I should see if I can find J. C. Whitney!

Jon

It sounds like the failure may have been fatigue. You might need a preformed or 3D shape with pleated rings molded into the material for a certain amount of movement.

Most times I've seen diaphrams that were intended to respond to a reciprocating stroke (some applications with a spring on one side), they have had the rings molded into the material.