This 1/2 inch flow measurement valve 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, a position indicator, memory device, checked metering ports with drip caps, two brass pressure taps, integral drain ports, and a brass drain plug. It has a compact size which 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, reheat coils, panel coils, small branch lines, unit heaters, unit ventilators, finned radiation, small domestic hot water lines, convectors, and small pumps.