6
AGL_Stream_ST_A2L_A1_4M_6M_EN_Rev00
2.5.3 Liquid injection / Demand cooling
WARNING
Ignition source in a potentially flammable atmosphere! Fire hazard!
The
solenoid valve of the liquid injection is not an ignition source during normal
operation in an A2L-refrigerant system but could become one if not installed
properly. Never operate the solenoid coil when not positioned on the solenoid
valve. Secure the installation with a screw.
"Demand Cooling" as the term implies means liquid refrigerant injection on demand.
Liquid injection may be required for low temperature applications in order to keep the compressor
within safe discharge temperature limits. The liquid injection system consists of an electronic
expansion valve with a solenoid coil, controlled by the Copeland compressor electronics system
(dedicated "Liquid injection" extension module C to be ordered).
For low temperature applications with R454C, R455A and R454A, liquid injection can be required on
the following compressors:
4MF-13X
4ML-15X
4MM-20X
4MT-22X
4MU-25X
6MM-30X
6MT-35X
6MU-40X
NOTE: For corresponding application envelopes, please see Select software available at
www.climate.emerson.com/en-gb.
2.5.4 Unloaded start
WARNING
Ignition source in a potentially flammable atmosphere! Fire hazard!
The
solenoid valve of the unloaded start is not an ignition source during normal
operation in an A2L-refrigerant system but could become one if not installed
properly. Never operate the solenoid coil when not positioned on the solenoid
valve. Secure the installation with a screw.
Unloaded start is mainly required for compressors connected for part-winding start (for example with
motor version AWM) or star-delta start (motor version EWM).
4M* and 6M* compressors can be equipped with an internal unloaded start system, to be ordered as
an option. The compressor prepared for unloaded start is supplied with a special cylinder head. The
control valve and coil are positioned on the top of the cylinder head. An additional check valve must
be installed in the discharge piping. Recommended inbuild position for the check valve is
approximately 50-100 cm to the compressor discharge connection.
Usually, the unloaded start is activated once for about 5-10 seconds shortly before compressor start
and then kept closed during operation. The unloaded start solenoid valve opens a suction channel
in the valve plate and the pressure in the discharge line equalizes to the suction side.
A. Standard operation
B. Unloaded start operation
Figure 3
1
Special cylinder head
2
Solenoid
3
Valve
4
Spring-loaded control piston
5
Suction side
6
High side in the cylinder head
7
Valve plate
1
6
5
2
3
4
7
1
1
