Maneurop horizontal valve/Rotalock valve/Stop valve

This group covers the three service valve styles used on commercial compressors and receiver assemblies: the Maneurop horizontal valve, the Rotalock valve, and the standard copper stop valve. They look similar in a photograph but the mounting and the thread are different, and fitting the wrong one is the usual reason a compressor change takes longer than it should.

The MV series is the horizontal valve for Maneurop-style compressors, with the body lying along the compressor connection so that the spindle is accessible from the side. Nine sizes cover 3/8 inch to 2-1/8 inch copper, with valve bodies from 20x20 to 45x45 mm. The RV series is the Rotalock pattern, where the valve screws onto a threaded stub on the compressor or receiver with an O-ring seal and is then locked by a nut - the advantage being that the valve can be removed without cutting pipe. The SV series is the conventional stop valve with solder connections, used on receivers, liquid headers and line ends.

Across the three series the connections run from 3/8 inch to 2-1/8 inch, or metric 10 mm to 54 mm, and the compressor-side threads from 1 inch-14UNS to 2-1/4 inch-12UNF. That range covers the compressor sizes normally found on cold room and small industrial packages.

Selection is by matching three things: the compressor stub thread, the line size, and whether the valve has to be removed for service (Rotalock) or can be permanently brazed (SV). A valve with the right line size but the wrong thread will not seal, and adapters are a common source of leaks on discharge lines.

All three are supplied with a service port and cap for gauges and charging. When fitting, lubricate the O-ring on Rotalock valves with refrigerant oil, and do not over-tighten the locking nut - it seals on the O-ring, not on torque.