Daikin DWSC079 Installation, Operation And Maintenance Manual page 24

Compressors using chilled water for oil cooling will often start with warm "chilled water" in the system until the chilled
water loop temperature is pulled down. Data given above includes that condition. As can be seen, with cooling water
in the 45F to 65F (7C to 18C) range, considerably less water will be used, and the pressure drop will be greatly
reduced.
When supplied with city water, the oil piping must discharge through a trap into an open drain to prevent draining the
cooler by siphoning. The city water can also be used for cooling tower makeup by discharging it into the tower sump
from a point above the highest possible water level.
NOTE: Particular attention must be paid to chillers with variable chilled water flow through the evaporator.
The pressure drop available at low flow rates can very well be insufficient to supply the oil cooler with enough
water. In this case an auxiliary booster pump can be used or city water employed.
Figure 8, Oil Cooler Piping Across Chilled Water Pump
Figure 9, Oil Cooler Piping With City Water
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PUMP
STOP
VALVE
STRAINER
MAX. 40 MESH
STOP
WATER
VALVE
SUPPLY
STRAINER
MAX. 40
MESH
CHILLER
OIL COOLER
SOLENOID
VALVE
R
OIL COOLER
S
SOLENOID
VALVE
DRAIN VALVE
OR PLUG
R
S
DRAIN VALVE
OR PLUG
COOLING TOWER
COOLING TOWER MAKEUP
DISCHARGE ABOVE
HIGHEST POSSIBLE
WATER LEVEL
OPEN
DRAIN
STOP
VALUE