SPX Cooling Technologies Marley MH 05-116E - Manual (Page 16)

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4. air flow rate: Reducing air flow through the fluid cooler causes the cold
process fluid temperature to rise. This is the recommended method
by which to control leaving process fluid temperature.
If your fluid cooler is equipped with a single-speed motor, the motor
may be shut off when the process fluid temperature becomes too
cold. This will cause the process fluid temperature to rise. When the
fluid temperature then becomes too warm for your process, the motor
can be restarted.
When operating in this mode care must be taken not to exceed a total
fan acceleration time of 30 seconds per hour.
Fan cycling limits: From a dead stop, determine the number of sec-
onds it takes the fan to arrive at full speed. Divide this number into 30
to determine the allowable number of starts per hour. Considering the
normal fan and motor sizes utilized on MH Fluid Coolers, anticipate
that approximately 4 to 5 starts per hour are allowable.
If your fluid cooler is equipped with a two-speed motor(s), you will
enjoy greater opportunity for process temperature control. When the
process fluid temperature becomes too cold, switching the fan to
half-speed will cause the cold process fluid temperature to rise—
stabilizing at a temperature a few degrees higher than before. With a
further reduction in fluid temperature, the fan may be cycled alternately
from half-speed to off—subject to the same constraint of 30 seconds
of allowable acceleration time per hour as outlined above.
For greater insight on process fluid temperature control, please read
“Cooling Tower Energy and its Management”, Technical Report
#H-001-A, available at spxcooling.com.
Wintertime Operation:
The Marley film-fill system used in the MH Fluid Cooler has air entrance
louvers that are molded as an integral part of the fill. This feature makes
these fluid coolers very forgiving of cold weather operation, even at the low
temperature and reduced load conditions encountered in low temperature
applications. Nevertheless, during operation in subfreezing weather the op-
portunity exists for ice to form in the colder regions of the fluid cooler.
Operation
Caution