
GENER
AL INFORMA
TION
PR
ODUC
T INFORMA
TION
SY
STEM DESIGN
INTEGR
ATION INT
O SY
STEM
ORDERING INFORMA
TION
Oil temperature sensor must be placed between
oil sight glass and compressor baseplate. Some
thermal paste shall be used to improve the
conductivity. The sensor must also be correctly
thermally insulated from the ambiance.
The Oil superheat is defined as:
(Oil temperature - Evaporating temperature)
14
16
18
12
10
8
6
4
-30
-25
-20
-15
-10
-5
0
5
10
15
20
25
-22
-13
-4
5
14
23
0
32
50
59
68
77
30
86
2
0
Unacceptable
Acceptable
Dilution chart
(reference at 20°C / 68°F ambient temperature)
Evaporating Temperature °C
Evaporating Temperature °F
Oil Superheat (K
)
Oil Superheat (°F)
25
29
32
22
18
14
11
7
4
0
Manage superheat
Test, criteria and solutions
Test N°
Purpose
Test condition
Pass criteria
Solutions
Liquid flood
back test
Steady-state
Liquid flood back testing must be
carried out under expansion valve
threshold operating conditions:
•Lowest foreseeable evaporation,
and highest foreseeable
condensation.
•Minimum speed running.
For reversible system, perform test
in both heating and cooling mode Suction superheat >5K
1. Check expansion valve selection
and setting.
-For Thermostatic expansion valve
(TXV) check bulb position...
-For Electronic expansion valve
(EXV) check measurement chain and
PID....
2. Add a suction accumulator*.
Transient
Tests must be carried out with most
unfavorable conditions :
•
fan staging,
•
compressor staging
•
…
Oil superheat shall not be more than
30 sec below the safe limit defined in
the Dilution Chart. (see graph above)
Defrost test
Check liquid
floodback
during defrost
cycle
Defrost test must be carried
out in the most unfavorable
condition at 0°C (32°F) evaporating
temperature).
Oil superheat shall not be more than
30 sec below the safe limit defined in
the Dilution Chart. (see graph ablve)
1.Check defrost logic.
In reversible systems, the defrost
logic can be worked out to limit
liquid floodback effect. (for more
details see “Control Logic”).
2. Add a suction accumulator*.
*Suction accumulator offers protection by trapping the liquid refrigerant upstream from the compressor. The accumulator should be sized at least 50 % of the total system
charge. Suction accumulator dimensions can impact oil return (gas velocity, oil return hole size…), therefore oil return has to be checked according to section “Manage oil in the
circuit”.
A
SY
STEM DESIGN
29
AB237586440343en-000601