8.7.9 Water quality
8.7.9.1 Water quality control
When industrial water is used as chilled water, little furring may
occur; however, well water or river water, used as chilled water,
may cause much sediment, such as furring, sand, and so on.
Therefore, well water or river water must be filtered and softened
in softening water equipment before flowing into chilled water
system. If sand and clay settle in the evaporator, circulation of
chilled water may be blocked, and thus leading to freezing
accidents; if hardness of chilled water is too high, furring may
occur easily, and the devices may be corroded. Therefore, the
quality of chilled water should be analyzed before being used,
such as PH value, conductivity, concentration of chloride ion,
concentration of sulfide ion, and so on.
<50ppm
<50ppm
<30ppm
<200μV/cm(25℃)
<0.3ppm
<50ppm
<50ppm
8.7.9.2 Applicable standard of water quality for the unit
PH value
Total hardness
Conductivity
Sulfide ion
Chloride ion
Ammonia ion
Sulfate
Silicon
Iron content
Sodium ion
Calcium ion
No
No
No requirement
Table 8-9
7.5～9
h3: Water resistance of the longest water-loop distance,
includes:
pipe resistance, different valve’s resistance, flexible pipe
resistance,
pipe elbow and three-way resistance, two-way resistance or
three-way resistance, as well as filter resistance.
H4: the longest terminal resistance.
8.7.8.2 Installation the pump
a. The pump should be installed at the water inlet pipe, both of
which sides must mount the soft connectors for vibration-proof.
b. The backup pump for the system (recommended).
c. Units must with a main unit controls (Please see Fig. 8-22 for
the controls wiring diagram).
8.7.8 Selection and installation of the pump
The minimum chilled water flow is shown in the table 8-8
If the system flow is less than the minimum unit flow rate,
the evaporator flow can be recirculated, as shown in the
diagram.
8.7.6 Maximum chilled water flow
The maximum chilled water flow is limited by the permitted
pressure drop in the evaporator. It is provided in the table 8-8
If the system flow is more than the maximum unit flow rate,
bypass the evaporator as shown in the diagram to obtain a lower
evaporator flow rate.
8.7.5 Minimum chilled water flow
For maximum chilled water flow rate
Evaporator
Recirculation
For minimum chilled water flow rate
Fig. 8-28
8.7.7 Minimum and Maximum water flow
Evaporator
Recirculation
Fig. 8-29
Table 8-8
Waterflow rate(m
3
/h)
Maximum
Minimum
Item
Model
13.0
ECH060N
8.0
6.4
ECH030N
3.8
16.5
ECH090N
13.5
8.7.8.1 Select the pump
a. Select the water-flow of the pump
The rated water-flow must no less than the unit rated water-flow;
in terms of multi-connect the units, that water-flow must no less
than total units’ rated water-flow.
b. Select the left of the pump.
H=h1+h2+h3+h4
H: The lift of the pump.
h1: Main unit water resistance.
h2: Pump water resistance.
40
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