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Application of Liebert
®
CRV
Liebert CRV - PD - 265086 - 11.01.2018
2.1.2 Combination with other Cooling systems
Liebert
®
CRV may be combined with other cooling systems such as underflow CRAC units (e.g. retrofit
of current installation) until there is proper setting of both systems without influencing each other. Oth
-
erwise there is a risk of cycling or increased power consumption of both systems, in worst case causing
malfunction of the units. For details contact Vertiv sales representative.
2.2 Selection of Liebert
®
CRV unit(s)
2.2.1 Number and size
When designing a cooling solution using the Liebert
®
CRV unit(s), the initial steps are similar to those
required to cool a conventional critical space. The total heat load must be calculated, including sensible
and latent cooling requirements. These should be increased by the reserve capacity needed for pull-
down situations (e.g. after power failure) where the room temperature must be reduced and to cover
unexpected increases in the heat load. Consider also redundant capacity, which is usually not in use in
the normal operation, but takes duty if any of the running unit(s) fail.
So the different steps are:
•
Check the heat load of IT equipment and apply safety margin if required.
•
Define size and number of Liebert
®
CRV units in order to provide enough net sensible cooling ca-
pacity to cover the heat load. Typical air inlet temperatures to be considered for normal operation
of the unit(s) are between 33° C and 37° C. Please refer also to point 2.2.3 Air Flow Requirements
•
When N+X (typical N+1) redundancy is required, use more units so if any of the unit(s) fail, the
remaining unit(s) will cover the heat load. Always consider the layout of the room when defining
number of units, see chapter 2.4 Positioning-unit placement.
2.2.2 Air Flow Requirements
Liebert
®
CRV is optimized to provide precision cooling for IT equipment with temperature raise (delta T)
of cooling air passing through the equipment around 15 to 20 degrees Celsius or higher. Such tempera-
ture raise is typical for Blade servers and standard pizza servers. For applications with very low delta T,
around 10 degrees Celsius, typical for old fashion servers, it is necessary to de-rate cooling capacity of
the Liebert
®
CRV due to higher air flow equipment.
In case of application with Cold Aisle Containment (Smart Aisle) it is necessary to carefully investigate
the air flow through IT equipment and to define number of Liebert
®
CRV units in order to provide at
least 5% more airflow, excluding redundant unit(s). Otherwise there may occur a situation with negative
pressure in the Smart Aisle containment and hot air possibly leaking inside the containment.
2.3 Operating limits
The units are designed to operate within working ranges.
These limits are referred to new machines or to those that have been correctly installed and serviced.
The warranty clauses are no longer valid for any possible damage or malfunction that may occur during
or due to operation outside the application values.
2.3.1 For all units
From:
To
Room air conditions
Temperature
27°C
40°C
Humidity ratio
5.5 g/kg
11 g/kg
Relative humidity
20 %
60 %
Storage conditions
Temperature
- 20°C
50°C
Relative humidity
Max. 90% RH, preventing
surface condensation.
Power supply tolerances
V ± 10 %
Hz ± 2
Summary of Contents for Liebert CRV 300 CW
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