The 142 series low lead manual balancing valves are used to measure and adjust the fluid flow rate in hydronic or plumbing circuits. Turning the knob moves a plug within the fluid stream which varies the flow rate. The flow rate is determined from the pressure drop created across the two test ports as the fluid passes the adjustment plug. The pressure drop value is measured by a differential pressure meter connected to the pressure test ports. The valve design is variable orifice with pressure ports located upstream and downstream of the adjustment plug. A memory stop feature allows the valve to be closed, and later reopened to the original set position.