Chapter 3 Installation
UD-series Screw Compressor
3.2 Installation Works
3-8
Piping Connection
Refrigerant Piping
Observe the following when connecting the refrigerant piping to the compressor.
The compressor is one of the few devices installed within the package unit that have moving
components. These moving components are adversely affected by foreign substances within
the system (scale, dust, spatter, etc.). Therefore, when connecting the piping, do not allow any
of such foreign substances to enter inside.
Some compressors (mainly those for export) are charged with nitrogen gas to prevent rust.
Be sure to release the pressure before starting piping work.
Be sure not to allow moisture to enter the piping. There is a high probability that it will cause
trouble after the start of operation. Be sure to assemble piping when it is dry.
Improper piping may cause operating problems such as oil not returning to the compressor or
liquid flow-backs.
When connecting the piping to the compressor, use piping that is the same size as the
compressor connection port. If the pipe size of the piping is smaller than the compressor
connection port, the flow of lubricating oil or refrigerant will be obstructed leading to problems.
Do not let the mass of the piping connected to the compressor applied onto flanges or joints.
Be sure to prepare proper supports for piping.
Equipment and Devices for Protection of the Compressor
Oil Filter
According to the requirements of the use of the package unit or the standard to apply, install an oil
filter of appropriate filtration precision in the lubrication system of the compressor.
In the case of general applications such as closed-cycle refrigeration systems, we recommend to
use an oil filter with beta ratio in the range of
β
20
≥ 150 that conforms to requireme
nts of NAS 1638
class 8 or ISO 4406 17/15/13.
When the package unit requires API 619 4th/5th edition conformity, use an oil filter with beta ratio in
the range of β
10
≥200.
The oil filter may be clogged just after commissioning. We recommend installing two oil filters in
parallel. This will enable replacement of either filter during operation.
Oil Heater for Oil Separator
To preserve the temperature of the lubricating oil before starting the compressor, install an oil
heater on the oil separator. Make sure to install a protection function (thermostat, or like) to prevent
overheating.
Suction Strainer
When inter-soluble oil is used, the mesh size of suction strainer should be not less than 200
meshes. When non-miscible oil is used, it should be not less than 100 meshes.
For details about inter-soluble and non-inter-soluble oils, see Section 4.1 "Lubricating Oil
(Refrigerant Oil)" in this manual.
During the commissioning, small particles and scale may come from the system. We recommend
installing a finer filter temporarily.
Compressor Protective Devices (Safety Devices)
To protect the compressor, install the necessary protective devices as described in Section 1.4.3
"Compressor Protective Devices" in this manual.
