The water that is being supplied to the heat exchanger must meet the requirements that are described in
this section.
Do not use glycol solutions because they can adversely affect the cooling performance of the heat
exchanger.
Cooling loop requirements
A secondary cooling loop, separate from the main site cooling loop, is required for the rear door heat
exchanger. Cooling distribution units are available from suppliers such as Coolcentric.
The secondary cooling loop must meet the requirements that are outlined in the water chemistry
specication. For more information about water chemistry requirements, see Water cooling system
specication and requirements.
Water-supply requirements for secondary loops
Learn about the specic characteristics of the system that supplies the chilled conditioned water to the
heat exchanger.
Temperature:
The heat exchanger and its supply hose and return hoses are not insulated. Avoid any condition that
might cause condensation. The temperature of the water inside the supply hose, return hose, and
heat exchanger must be kept above the dew point of the location where the heat exchanger is being
used.
Attention:
Typical primary chilled water is too cold for use in this application because building
chilled water can be as cold as 4°C - 6°C (39°F - 43°F).
Important:
The system that supplies the cooling water must be able to measure the room dew point and
automatically adjust the water temperature accordingly. Otherwise, the water temperature must be
above the maximum dew point for that data center installation. For example, the following minimum
water temperature must be maintained:
• 18°C plus or minus 1°C (64.4°F plus or minus 1.8°F). This specication is applicable within an
ASHRAE Class 1 Environmental Specication that requires a maximum dew point of 17°C (62.6°F).
• 22°C plus or minus 1°C (71.6°F plus or minus 1.8°F). This specication is applicable within an
ASHRAE Class 2 Environmental Specication that requires a maximum dew point of 21°C (69.8°F).
See the ASHRAE document Thermal Guidelines for Data Processing Environments.
Pressure:
The water pressure in the secondary loop must be less than 690 kPa (100 psi). Normal operating
pressure at the heat exchanger must be 414 kPa (60 psi) or less.
Flow rate:
The flow rate of the water in the system must be in the range of 23 - 57 liters (6 - 15 gallons) per
minute.
Pressure drop versus flow rate for heat exchangers (including quick-connect couplings) is dened as
approximately 103 kPa (15 psi) at 57 liters (15 gallons) per minute.
Water volume limits:
The heat exchanger holds approximately 9 liters (2.4 gallons). Fifteen meters (50 ft) of 19 mm (0.75
in.) supply and return hoses hold approximately 9.4 liters (2.5 gallons). To minimize exposure to
flooding in the case of leaks, the entire product cooling system (heat exchanger, supply hose, and
return hose), excluding any reservoir tank, must have a maximum 18.4 liters (4.8 gallons) of water.
This is a cautionary statement, not a functional requirement. Also, consider using leak detection
methods on the secondary loop that supplies water to the heat exchanger.
Site and hardware planning
49
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