ULT Energy-saving Series
After-sales Service Manual
29
freezer capacity.
4) Prohibition: All ULT Freezers are low temperature storage equipment, which are used to store low temperature
items, and are not allowed to be used for quickly freezing plasmanate with high temperature. It is strictly prohibited
to put too many relatively hot items at one time, which may cause the compressor to stay in operation for a long
time, the temperature will not drop, and it is easy to burn the compressor, resulting in damage to the items in the
freezer. Items must be put into in batches, cool by stages until get the required low temperature!
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7.3 Working principle of pressure switch
A. Principle: When the pressure in the pipeline at the pressure switch exceeds 2.1 MPa, the contact is disconnected,
the ULT Freezer stops, and the pressure begins to drop. When the pressure drops to 1.35 MPa, the contact is
connected, and the ULT Freezer starts up. When the pressure exceeds 2.1 MPa again, the contact is disconnected
again, and the followed steps circulate in turn.
B. Precautions: When welding the pressure switch, place a wet towel on it to keep the temperature not higher than
100°C. The parameters of the pressure switch are not adjustable.
C. Parameters: Voltage: 220 V, 50 Hz, contact capacity: 6A.
7.4 Characteristics of refrigerant
1) The refrigerant is a mixed working medium, which is inflammable and explosive. Refrigerant charging place shall
be well-ventilated, and ignition or sparking is not allowed nearby in case of leakage. If there is a problem in the
refrigeration system, the local after-sales service site shall judge and give feedback on the problem, and the technical
personnel of Medical Business Division shall instruct the local after-sales site to carry out repair and maintenance as
per specific situation.
2) Refrigerant code
(energy-saving): R290 for high temperature stage system; R290 and R170 for low
temperature stage system (R600A, R1150 and R50 forDW-86L100J)
7.5 Refrigerant charging procedures:
7.5.1 Preparation
1)
Refrigerant (R290, R170)
2) Hansen valves
3) Standard electronic scale (error ≤ ±2 g)
4) Vacuum pump ( ≥ 4 L)
5) Pressure gauge (it is required to read high and low voltage at the same time) is shown in Figure 1
7.5.1 Open the system
1) Cut the system with fault from the end of process pipe with pipe tongs, and discharge the refrigerant in the
system.
2) Weld the opened pipeline to the pressure gauge within 20 minutes after opening the system.
[Precautions]
*This product series is a two-stage refrigeration system, which includes two independent systems, i.e. the
