The HM 650 reads differential or gage fluid pressure and can be used to balance heating and cooling systems or check pump performance. The company says its hydronic manometer can be hooked up to common valve and flow controllers, venturi meters, and orifice plate meters. The measurement range of the HM 650 is 0-300 psi in an operating temperature range of 40°F to 113°F. It features a 0.05-psi resolution.
— Alnor Instruments Co.