Midea MWSC340A-FB3 - Page 99

Flooded type water cooled screw chiller (PCB Control)
98
Low pressure-chilled water temperature (low pressure beyond 0.14~0.37MPa is abnormal)
Fig.27 Low pressure at full load (standard unit)
Cleaning work must be done when too much scale found. Physical and chemical cleaning can be
chosen according to the device you have. Generally, chemical cleaning is much easier to carry out.
Methods are as below and the services of a qualified water treatment specialist should be obtained to
develop and monitor a treatment program.
a) Cycle under normal temp. (A):
(Volume of condenser+ volume of pipes+ volume of container)×1/3
Note: concentration of detergent ——33%
b) Cycle under normal temp. (B):
(Volume of cooling tower flume + volume of condenser+ volume of pipes)×1/10
Note: concentration of detergent ——10%
Warning: When doing cleaning with unit stops, volume of cooling tower flume can be 1/2 or 1/3 of rated
value; but if doing cleaning with unit is runs, the volume of cooling tower flume should keep rated value.
Midea assumes no responsibility for pressure vessel damage resulting from untreated or improperly
treated water.
Requirement for cleaning and maintenance
Water quality
Scale
Corrosion
Remark
1
PH≤6 Acid water
Hard
Strong
Generates insoluble CaSO
4
2
PH≥8 Alkali water
Soft
——
Soft fluid deposit may be
caused by ions iron or
aluminum
3
Water with much Ca
2+
and
Mg
2+
Hard
——
Easily generates hard scale.
4
Water with much Cl
-
Dirt
Ultra-strong
Corrosive to copper and
iron.
5
Water with much SO
4
2-
and
SiO
2
2-
Hard
Strong
Generates hard CaSO
4
and
CaSiO
2
6
Water with much Fe
3+
Large quantity,
hard
Strong
Generates deposits Fe(OH)
3
and Fe
2
O
3
7
Odorous water
Large quantity
Ultra-strong
Generates sulfide, ammonia
and marsh gas, especially
H
2
S which has great
corrosion to copper.