7.3.7 Secondary Fluid Flow Considerations for Rear Door Heat Exchangers
Secondary fluid flow should be maintained between the values of 25 gpm (minimum) and 200 gpm (maximum) per running
unit depending on pump size.
Refer to individual cooling module specifications to estimate the maximum combined allowable flow for all units connected to
the Vertiv™ CoolPhase CDU. If the allowable combined flow rate is less than 25 gpm (5.8 m3/h) per CoolPhase CDU module,
adjust bypass valves (field provided) as necessary to maintain a flow above 25 gpm (5.8 m3/h) through the CoolPhase CDU.
For example, the maximum allowable water flow rate for a Vertiv™ Liebert® DCD unit is 22.7 gpm (5.2 m3/h). If four of these
units are connected in parallel to the CoolPhase CDU, you can have a total flow over 90 gpm (20.4 m3/h).
22.7 gpm X 4 DCD units = 90.8 gpm total flow
5.2 m3/h X 4 DCD units = 20.9 m3/h total flow
If only one of the Liebert® DCD20 units is connected to the CoolPhase CDU, you must open bypass valves (field provided) to
maintain the total flow through the CoolPhase CDU within the 25-170 gpm per module range.
7.3.8 Secondary Fluid Flow Considerations for Direct to Chip Cold Plates
Secondary fluid flow should be maintained between the values of 25 gpm (minimum) and 200 gpm (maximum) per running
unit depending on pump size.
Refer to individual IT specifications to estimate the maximum combined allowable flow for all IT cabinets connected to the
CoolPhase CDU. If the allowable combined flow rate is less than 25 gpm (5.8 m3/h) per CoolPhase CDU module, adjust bypass
valves (field provided) as necessary to maintain a flow above 25 gpm (5.8 m3/h) through the CoolPhase CDU.
7.3.9 Fluid Quality Requirements for Rear Door Heat Exchanger and Direct to Chip
Applications
The cooling water used must be soft enough to prevent deposits, but it must not be too soft because that would lead to
corrosion in the water system.
Water/glycol solutions have different requirements. As stated in the notice in Secondary Fluid Circuit Requirements on
page61 a local water treatment specialist could be consulted.
Table 7.5 below lists the most important impurities and measures for their removal.
Water Impurity or Condition Corrective Method
Particles (dp < 0.3 mm) Filter the water.
Excessive hardness Soften the water by ion exchange.
Moderate level of particles and hardeners Add dispersion or stabilization agents.
Moderate level of chemical impurities Add deadening agents and inhibitors.
Biological impurities (bacteria and algae) Add biocides.
Table 7.5 Water Impurity (Rear Door Heat Exchangers)
70 Proprietary and Confidential ©2024 Vertiv Group Corp.
7 Secondary Fluid Circuit
Requirements
Vertiv™ CoolPhase CDU Installer/User Guide
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