140.925-IOM (APR 2019)
Page 31
XLP3 EVAPORATIVE CONDENSERS
MAINTENANCE
the useful life of the equipment. The degree to which dissolved
solids and other impurities build up in the recirculating water
may be defined as the cycles of concentration. Specifically,
cycles of concentration equal the ratio of the concentration of
dissolved solids (for example - chlorides, sulfates, etc.) in the
recirculating water to the concentration of the same material in
the make-up water.
• In order to optimize heat transfer efficiency and maximize
equipment life, bleed or blowdown a small amount of
recirculating water from the system. This controls the
cycles of concentration to maintain the quality of the
recirculating water within the guidelines given in Table 5,
on page 25.
• Replenish the “bleed” water with fresh make-up water,
thereby limiting the build-up of impurities.
• Bleed/blowdown:
• To minimize water usage, accomplish the bleed
automatically through a solenoid valve controlled by
a conductivity meter. The set point is the water
conductivity at the desired cycles of concentration and
should be determined by a water treatment expert.
Bleed Line Calculations:
Bleed rate is determined by the fol-
lowing formula:
B =
E
(n-1)
Where: B = Bleed Rate (USGPM)
E = Evaporation Rate (USGPM) = Q (USGPM) x R (°F) x 0.001
Q = Process Fluid Flow Rate (USGPM)
R = Range
n = Desired Number of Cycles of Concentration = CR/CM
The evaporation rate is dependent on the wet bulb temperature
and load. The equation shown above provides the maximum
bleed rate on the design day. Contact your local Frick represen-
tative for an exact calculation based on specific site conditions.
NOTICE
A proper water treatment program, administered under
the supervision of a competent water treatment specialist,
is an essential part of routine maintenance to ensure the
safe operation and longevity of evaporative cooling
equipment, as well as other system components.
NOTICE
The solenoid valve and conductivity meter must be
supplied by others. Evaporation is proportional to the load
and will vary seasonally. Frick recommends the use of a
conductivity meter to maximize water conservation.
NOTICE
The approximate design evaporation rate (E) can be
determined by any one of the following methods:
• The evaporation rate is approximately 2 USGPM per 1
million BTUH of heat rejection.
• The evaporation rate is approximately 3 USGPM per 100
tons of refrigeration.
• Evaporation Rate = Q (USGPM) * R * 0.001.