30
8.14 PRESSURE CONTROLS
Both High and Low pressure switches are required on the compressor. The suggested cut out settings are
indicated in below Table:
Table
8.14 Pressure controls settings
R404A
R449A
R448A
R452A
R134A
R513A
Application
Type
Control
Type
Mpa
(rel)
Bar
(rel)
Mpa
(rel)
Bar
(rel)
Mpa
(rel)
Bar
(rel)
Mpa
(rel)
Bar
(rel)
Mpa
(rel)
Bar
(rel)
Mpa
(rel)
Bar
(rel)
MBP
Low
0.20
2.0
0.16
1.6
0.18
1.8
0.13
1.32
High
3.24
32.4
2.39
23.9
3.13
31.3
2.39
23.9
LBP
Low
0.13
1.3
0.10
1.01
0.12
1.2
--
--
High
2.90
29.0
2.73
27.3
2.82
28.2
--
--
8.15 INTERNAL PRESSURE RELIEF VALVE (IPR VALVE)
Scroll refrigeration compressors with 3 phase motor have internal pressure relief valves (IPR valve), which
open at a discharge to suction differential pressure of 2.76 – 3.10 Mpa (27.6-31 Bar). This action will trip the
motor protector and remove the motor from the line.
Single phase compressor are not equipped with IPR valve as motor is under lower overload ability and
properly protected by OLP only.
9. INSTALLATIONS
9.1 SYSTEM COMPONENTS COMPATIBILITY
All refrigeration system components shall be compatible with all approved refrigerants: R404A, R452A,
R449A, R448A, R134a, R513A and the oil charged in the compressor. Substances containing chlorine,
mineral oils, paraffin and silicone are not allowed.
All equipment used in the refrigerator manufacturing process that require lubrication
and may come into contact with the refrigeration system components, must use
exclusively polyolester oil as a lubricant (suggested viscosity 32 cSt @ 40°C).
Particular attention must be given to the internal cleanliness of the system, see
Chapter
11.1 – System cleanliness, avoid entering into the system of any solid residues
(dust, brazing flux, metal particles, etc.), humidity and free of debris or any particles
including copper residues.
IMPORTANT
