User's Manual

Piping
19 Liebert
®
DCP
™
3.4 Piping Installation Methods
The assembly and connection means used for piping in the Liebert DCW
™
system are similar to those
used for conventional refrigeration systems. All piping should be installed with high-temperature
brazed joints. Soft soldering is not recommended.
During brazing, the lines must be filled with flowing dry nitrogen to prevent excessive oxidation and
scale formation inside the piping. Prevailing good refrigeration practices must be employed for piping
supports, leak testing, dehydration and charging. Failure to use good system practices may result in
damage to the system. Refer to the ASHRAE refrigeration handbook for general good-practice
refrigeration piping.
Insulate all piping lines to prevent condensation in applications where the dew point approaches the
chilled water temperature.
3.4.1 Piping Mains
Install a 20-40 mesh strainer on the chilled water supply to the Liebert DCP. The strainer is needed
to prevent particles in the chilled water from entering the Liebert DCP’s heat exchanger.
3.5 Bypass Flow Controllers
The Liebert DCP pumping unit is designed to provide a total of 114GPM (25.9 m
3
/h) of cooling water
to the cooling modules. The pump operates at its highest efficiency between 90 and 120GPM
(20.4m
3
/h and 27.3m
3
/h). Permanent bypass flow controllers must be installed to ensure flow within
this range. Emerson
®
recommends using four 22.67 GPM (5.15m
3
/h) constant flow regulators or other
regulator of similar flow capacity as bypass valves. Bypass lines also prevent excessive flow through
the cooling modules when only a few modules are installed in addition to maintaining high flow rate
through pump.
Refer to individual cooling module specifications to estimate the maximum combined allowable flow
for all the units connected to the Liebert DCP. If the allowable combined flow rate is less than 90GPM
(20.4 m
3
/h), then as many bypass controllers as necessary must be opened to maintain a flow above
90GPM (20.4m
3
/h) through the Liebert DCP.
For example, the maximum allowable water flow rate for a Liebert DCD
™
unit is 22.7GPM (5.2 m
3
/h).
At least four of these units must be connected to the Liebert DCP in parallel to achieve a total flow of
over 90GPM (20.4m
3
/h).
22.7GPM x 4 Liebert DCD’s = 90.8GPM total flow
5.2m
3
/h * x Liebert DCD’s = 20.8m
3
/h total flow
If fewer units are connected to the Liebert DCP, then bypass lines must be opened to maintain the
total flow through the Liebert DCP within the range of 90 to 120GPM (20.4 to 27.3 m
3
/h).
For example, if three Liebert DCD modules are connected to a Liebert DCP, the total flow of 68.1GPM
(15.47 m
3
/h) would be insufficient. A bypass flow controller of 22.67GPM (5.15 m
3
/h) must be added to
increase the flow rate to at least 90GPM (20.4m3/h)
22.7GPM x 3 Liebert DCDs = 68.1GPM
22.7GPM x 3 Liebert DCDs + 22.67GPM bypass flow controller = 90.77 GPM
5.2m
3
/h * 3 Liebert DCDs = 15.47m
3
/h
5.2m
3
/h *3 Liebert DCDs + 5.15m3/h bypass flow controller =20.75m3/h