The Siemens MVS661 valves are designed as solenoid valves and modulating control of refrigerant circuits including chillers and heat pumps. The valve is designed as an expansion valve and for controlling liquid, suction gas and pressure gas in systems with NH3, CO2 and synthetic refrigerants.
By generating a magnetic field, depending on the voltage, a spindle will be moved up and down. This will result in opening and closing of the valve. If the magnetic field fails(de-energized) the valve is closed. The valve opening is determined by a electronic input signal (0/2..10VDC or 0/4..20mA) through the integrated electronic circuit. The valve opening is linear with the input signal. Standard PI(D) controllers or PLC with PI(D) characteristics with an output signal of 0/2..10 VDC or 0/4..20mA can be used for controlling the valve.
Because valve movement is very quick and the valve can only be influenced by input signal and not by pressure or temperature fluctuations in the refrigerant, a very accurate and rapid control circuit can be achieved. Depending on the circuit these valves can also be used as solenoid valves(open/closed).
In DX systems, the control speed is determined by the response time of pressure and temperature sensors (pay special attention to the temperature sensors).
The insert of the valve is replaceable without dismantling. The Kv value of the valve can be changed easily.
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