Stainless Steel 1/8 Inches Pneumatic Adjustable Pump Pressure Switch QPM11-NO Normally Open

Good. Easy to use. Good price. Doesn't come with Allen wrench to adjust but I have tons anyways. Good for a replacement. I have one with a low set pressure and needed to adjust for more PSI. This did the trick

These pressure type switches work for replacement of equipment that has pressure switches that are faulty and have been disconnected in order to allow the equipment to operate, though without the safe guard of low pressure creating issues for other things on the machine. You can adjust the settings on these to trigger at a particular set pressure point, making it very useful for multiple applications. Just be sure to get the right one for the right job. NC Normally Closed or NO Normally Open.

If you try to use this to control a relay to control a compressor at a fixed pressure, you will be disappointed. This sensor is so sensitive about switching at exactly the set point it chatters on and off when it reaches the set point. The fancy name for this is hysteresis, it has none. Your compressor will come up to the set point and as soon as it reaches it it will pulse and surge many many times before it finally settles down and as soon as the tank pressure changes at all, the compressor will come back on. This is really hard on a compressor and an electrical system. The sensor is not suitable for that purpose and they really ought to publish a spec about hysteresis because I'm sure I'm not the only person that just wanted an adjustable pressure switch for their compressor tank.It would be impressive as a sensor to detect a small change in pressure, however so I'm not going to rate it negatively.

They work nice slightly sensitive bought 2 one quit working after 3 days , not sure why but it won't shut off anymore second one I didn't use yet

Good build quality and works as described.

But when you set the pressure it fluctuates and your compressor cycles on and off, which I don’t like

We used this switch to add a buzzer to our PTO. We had issues with guys forgetting to turn the PTO off on our tow truck and driving off. We rigged this up so that if the brakes were released and the PTO was still on a buzzer would go off. Works great and we plan on doing the same on the rest of our trucks with air brakes and PTOs.

Worked for my application. I needed it to verify when a cylinder had reached the end its travel.