Pipe Connections; Pipes; Start Unloader (External) - GEA Bock EX-HG88e Series Assembly Instructions Manual

4 | Compressor assembly

4.3 Pipe connections

Fig.12: graduated
internal diameter

4.4 Pipes

Pipes and system components must be clean and dry inside and free of scale, swarf and layers of
D
rust and phosphate. Only use air-tight parts.
GB
Lay pipes correctly. Suitable vibration compensators must be provided to prevent pipes being
cracked and broken by severe vibrations.
F
Ensure a proper oil return.
E
Keep pressure losses to an absolute minimum.
I

4.5 Start unloader (external)

A internal start unloader ex factory is not available. Alternatively a start unloader can be installed in
the plant. Monitoring, including the parts used, must comply with Directive 2014/34/EU.
Operation:
When the compressor is started, a solenoid valve receives power via a time switch and opens a by-
pass between the discharge- and suction line. At the same time, a non-return valve in the discharge
line closes and prevents a backflow of refrigerant from the condenser (Fig. 13).
The compressor is now short-circuited and delivers from the outflow directly into the intake. The
pressure differential consequently decreases substantially. As a result, the torque on the drive shaft
of the compressor is considerably diminished. The drive motor can now start with a low level of
starting torque. As soon as the motor and the compressor reach their rated speed, the solenoid valve
closes and the non-return valve opens (Fig. 14). The compressor now works under normal load.
18
The pressure and suction shut-off valves have graduated inside dia-
meters so that pipes in the common millimeter and inch dimensions can
be used. The pipe will be inserted more or less deep, depending on the
dimension.
The connection diameters of the shut-off valves are designed for maximum
compressor performance. The actual required pipe cross section must
be matched to the output. The same applies for non-return valves.
ATTENTION An explosive atmosphere must not be present!
Do not solder as long as the compressor is under pressure.
Superheating can damage the valve. Remove the pipe supports the-
refore from the valve for soldering and accordingly cool the valve
body during and after soldering.
Only solder using inert gas to inhibit oxidation products (scale).
Solenoid valve actuated
Non-return valve closed
Fig. 13