D
–EIMAC01905-23_00EN - 36/53
Coolant quality requirements
There are three main reasons for this suggested minimum advised content of glycol:
1. Corrosion protection
2. PH buffering increasing
3. Inhibition of the proliferation of most bacteria and fungi
In alternative to water+glycol, to ensure the long operating life of microchannel free cooling coil, the following conditions
for coolant shall be respected:
Table 15
– Free cooling application coolant quality requirements for MCH coils
Coolant quality requirements
Value
Ph (25 °C)
7.5 ÷ 8.5
Ammonium ion [mg NH
4+
/ l]
< 2
Chloride ion [mg Cl
-
/ l] (water temp. < 65°C)
< 10
Sulphate ions [mg SO
4
2-
/ l]
< 30
Fluoride ions [mg F
-
/ l]
< 0.1
Fe2+ and Fe3+ ions (if dissolved oxygen present >5mg/l) [mg
/ l]
0
Fe2+ and Fe3+ ions (if dissolved oxygen present <5mg/l) [mg / l]
< 5
Zn ions (ethylene glycol solution application)
0
Silica [mg SiO
2
/ l]
< 1
Total Hardness [mg CaCO
3
/ l]
100 ÷ 250
Total alkalimetric title (TAC) [mg / l]
< 100
Electrical conductivity [mS/m] (25 °C)
20 ÷ 60
Specific resistance [Ohm / m]
> 30
Notes:
-
Dissolved oxygen: any sudden change in water oxygenation conditions is not expected.
-
The addition of corrosion inhibitor is necessary for ensured coil protection, e.g. those based on monopropylene
glycol or sodium molybdate.
-
Maximum opening for strainer mesh shall be 1mm.
The most appropriate water treatment must be determined locally, according to the type of system and water
characteristics.
The manufacturer is not responsible for damage to or malfunctioning of equipment caused by failure to treat water or by
improperly treated water.
First operations at unit commissioning start
Free cooling section is pressurized before shipping up to 1-2 bar with nitrogen. To do so, it is necessary to disable free
cooling by PLC and close manually
the valve ”d” (see. Fig. 25); valve ”1” will close automatically when disabling free
cooling.
When commissioning the unit, it is necessary to:
-
O
pen valve ”d”
-
Enable free cooling operation from PLC
-
After coolant (water + glycole) charge operation, it is necessary to vent the unit. Use venting valve installed on
top of MCH coil to do this operation.
The minimum advised content of glycol is 25% (ethylene or propylenic).
For operation at less than -10°C the percentage of glycol must be determined by the installer.
The use of other substances different from ethylene or propylenic glycol shall be approved by the
factory.
For operation below +4°C the use of glycol is mandatory.