Model RH-3 and RH-3-2 Differential Pressure Switches monitor low-air pressure, vacuum, or differentials of air pressure. These switches are commonly used to prove blower operation, to sense dirty filters, and to monitor pressure drop across coils. Models RH-3 and RH-3-2 are shipped with 1/4" compression fittings, suitable for use with 1/4" OD copper or plastic tubing, and a 12" (30.5 cm) length of 1/4" plastic tubing. SPECIFICATIONS Setpoint range RH-3 0.05" to 12.0" W.C. (12.5 to 2989 Pa) RH-3-2 0.05" to 2.0" W.C. (12.5 to 498 Pa) Switch differential 0.02" (5.0 Pa) W.C. @ min setting, 0.8" (199.5 Pa) W.C. @ max setting Contacts SPDT Electrical rating 300 VA pilot duty @ 125-277 VAC 15A resistive @ 125 VAC 1/4 hp @ 125 VAC 1/2 hp @ 250 VAC 2.4A @ 24 VAC 0.5A @ 24-125 VDC Max overpressure 0.5 psig (3.45 kPa) Operating temp -40 to 180F (-40 to 82C) Mounting position Diaphragm in vertical plane Pressure connection 1/4" compression (suitable for use with 1/4" OD copper or plastic tubing) Approvals UL, CSA Weight 2.0 lb (0.92 kg)