Apollo™ Model 58A Balance Valves are precision engineered and manufactured valves which provide two position hydronic circuit isolation capability and multi-turn throttling adjustment as required for proportional balancing of hydronic systems. The unique integrated digital readout in the handle allows qualified technicians to easily adjust the valve to achieve a highly accurate flow. Valve pressure drop can be read through the valves integrated 1/4 in measurement ports, and flow calculated from the flow coefficient associated with the numerical setting. The integrated fixed orifice offers greater accuracy than that of a variable orifice.