Mid-West Instrument’s Model 522 differential-pressure/indicator switch is a diaphragm-type unit that features complete high-to-low side isolation, making it a good fit for low-flow monitoring of heat exchangers in geothermalapplications. The switch features a max. static pressure of 1,000 PSIG(69 bar), a max differential over-range pressure of 200 PSID (13.89bar) and differential-pressure ranges of zero to five and zero to 50PSID with  +/- 5 percent full scale accuracy. Body materials arealuminum or 316/316L stainless steel with 316 SS, ceramic and acetalmoving parts. The 522 unit is available with one or two fieldadjustable (40 percent to 100 percent full scale) hermetically sealedreed switches in SPST (3 amp) configuration.  Features up to 240VAC/VDC voltage ratings, flying leads, or DIN-type connectors and canbe custom-designed to meet mounting requirements or operatingconditions. Dial accuracy +/-5 percent standard with a five-yearwarranty.