This flow measurement valve, 1 inch, monitors system flow in low to medium flow rate HVAC units, providing a highly accurate flow measurement. It consists of bronze body construction with bi-directional, positive shutoff ball valve design, blow-out proof stem, memory device, a position indicator, checked metering ports with drip caps, integral drain ports, two brass pressure taps,thread connections, and a brass drain plug. The compact size allows for easy installation and access in a crowded piping environment. It is ideal in hot/chilled water units such as fan coil units, water source heat pumps, panel coils, reheat coils, small branch lines, unit heaters, finned radiation, small domestic hot water lines, unit ventilators, convectors, and small pumps.