SPX Cooling Technologies Marley MD Humidifier User Manual


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17
Caution
Slushy, transitory ice forms routinely in the colder regions of the ll at
low temperature. Such ice normally has no adverse effect on tower
operation, but its appearance should be a signal to the operator to
undertake ice control procedures.
It is the operator's responsibility to prevent the formation of destruc-
tive (hard) ice on the cooling tower ll and louvers. Certain guidelines
should be followed:
1. Do not allow the tower’s leaving water temperature to drop below a
minimum allowable level—say 36°F to 40°F. If such low temperature
operationisnecessaryorbenecialtoyourprocess,establishthe
minimum allowable level as follows:
Duringthecoldestdaysoftherstwinterofoperation,observewhether
anyiceisformingonthebottomofthellorthelouvers.Ifhardiceis
present on either component, you must increase the allowable cold
watertemperature.Ifthecoldestpossiblewaterisbenecialtoyour
process, ice of a mushy consistency can be tolerated—but routine
periodic observation is advisable.
If the minimum allowable cold water temperature is established at
or near minimum heat load, it should be safe for all operating condi-
tions.
Having established the minimum allowable cold water temperature,
maintaining that temperature can be accomplished by fan manipula-
tion, as outlined in Item 4 under Tower Operation. However, in towers
of more than one cell, where fans are manipulated sequentially, please
realizethatthewatertemperaturewillbesignicantlylowerinthecell
or cells operating at the highest fan speed than the net cold water
temperature produced by the entire tower would indicate. Wintertime
operation of multicell towers at low cold water temperature levels
requires that the operator be especially watchful.
2. Under extended extreme cold conditions, it may be necessary to
operate the fan in reverse. This forces warm air out through the
louvers, melting any accumulated ice—adequate heat load must be
available. Reversal may be at either full or half speed; however, we
recommend reversal at half speed or lower. Reverse operation of the
fan should be used sparingly and should only be used to control ice,
Note
Operation
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