Data Sheet for Product

MVS661…N Modulating Refrigerant Valves Technical Instructions
for Ammonia (R717) and Safety Refrigerants Document Number 155-404
May 11, 2016
Siemens Industry, Inc. Page 7
Engineering Notes
Depending on the application, additional installation instructions may need to be observed
and appropriate safety devices (such as pressostats, full motor protection, and so on)
fitted.
WARNING:
To prevent damage to the seal inside the valve insert, the plant must be
vented on the low-pressure side following a pressure test (valve outlet port),
or the valve must be fully open during the pressure test and during venting
(power supply connected and positioning signal at maximum or forced
opening by G  ZC).
Expansion application
To prevent formation of flash gas on expansion applications, the velocity of the refrigerant
in the fluid pipe may not exceed 3.3 ft/s (1 m/s). To assure this, the diameter of the fluid
pipe must be greater than the nominal size of the valve.
1 = Evaporator
2 = Compressor
3 = Condenser
4 = Expansion
valves
a) The differential pressure over reduction must be less than half the differential pressure
Δp
FL
.
b) The inlet path between diameter reduction and expansion valve inlet:
 Must be straight for at least 2 feet (600 mm).
 Must not contain any valves.
WARNING:
A filter/dryer must be mounted upstream of the expansion valve.
The valve is not explosion-proof.
Installation Notes
The valve should be mounted and commissioned by a qualified installer. The same applies to
the replacement electronics and the configuration of the controller.
 The refrigerant valves can be mounted in any orientation
above horizontal, but upright mounting is preferable.
 Arrange the pipework so that the valve is not located at a
low point in the plant where oil can collect.
 Fit the pipes so that the alignment does not distort the
valve connections. Fix the valve body so that that it cannot
vibrate. Vibration can cause connection pipes to burst.
 Before soldering the pipes, ensure that the direction of flow
through the valve is correct.
 Carefully solder the pipes. To avoid dirt and the formation
of scale (oxide), inert gas is recommended for soldering.