HSO 2024 to HSO 2035 Installation, Operation and Maintenance Manual
Issue 1.2 : 03/10
Publication 2-119
Page 49 of 94
(c)
If liquid injection oil cooling is fitted, check that stop valves are
open in the line supplying refrigerant to the liquid injection valve.
With the solenoid valve in the line energised (open), the sight-glass
in the line should be full of refrigerant.
Check that the stop valves in the the rest of the refrigeration
system are in their correct running positions.
(d)
If the plant is fitted with a water cooled oil cooler, start the water
circulation pump and check for adequate flow through the cooler.
(e)
Check the following:
•
Safety devices and interlocks are in a ‘safe’ condition.
•
Auxiliaries which are required to run before the compressor
starts, for example, the condenser water pump and/or
evaporator cooled medium pump, are providing interlock
‘running’ signals to the control system.
(f)
For safety reasons, select hand compressor start/stop - hand
capacity control operating mode for starting the compressor for the
first time and for the initial period of operation.
(g)
Start the compressor.
The following descriptions refer to applications using oil differential
pressure switches to sense system pressures.
No Oil Pump
After the compressor has started and been in operation for a short
time, allowing sufficient time for the system pressure differential to
become established, ODPS is brought into circuit. Oil is now being
supplied to the compressor under the action of the system
pressure differential monitored by ODPS. If the system pressure
differential falls below the switch contacts open setting, ODPS will
trip and stop the compressor motor.
Start-up Oil Pump
The oil pump starts before the compressor.
When sufficient oil pressure differential is available between the oil
reservoir outlet and the pump delivery, i.e. at least 1.5 bar,
contacts of ODPS2 close allowing the compressor start sequence
to proceed. After the compressor has started and been in
operation for a short time, allowing sufficient time for the system
pressure differential to become established, the oil pump is
stopped and ODPS2 electrically bypassed. At the same time
ODPS1 is brought into circuit. Oil is now being supplied to the
compressor under the action of the system pressure differential
monitored by ODPS1. If the system pressure differential falls
below the switch contacts open setting, ODPS1 will trip and stop
the compressor motor.
Continuously Running Oil Pump
The oil pump and compressor start together.
Providing the drain line is clear of oil, the oil pump and compressor
start together. ODPS is brought into circuit after allowing sufficient
time for the oil pump to start and contacts of ODPS to close.
ODPS will stop the compressor unless the oil differential pressure
has risen to 1.5 bar during the start period, and continues to
monitor this differential all the while the plant is in operation.
