SPX Cooling Technologies none user manual Intermittent Wintertime Operation

Operation

If the minimum allowable cold process fluid temperature is estab- Cautionlished at or near minimum heat load, it should be safe for all operat-

ing conditions.

Having established the minimum allowable cold water temperature, maintaining that temperature can be accomplished by fan manipulation, as outlined in Item 4 under Fluid Cooler Operation.

2.A fan operating in a forced-draft tower is subject to the risk of freez- ing. Icing is a particular danger as this can form not only on the fan blades, but also the inlet guard. Ice particles can be thrown off and cause severe damage. The fan casing should be checked so that any water entering it (either from the tower or external sources) can drain away. If water is allowed to collect in the fan casing, the fan could be frozen into place. This could result in damage to the drive system if starting were attempted.

3.As cold air enters the fluid cooler, it causes the falling water to be drawn inward. Thus, under fan operation, the lower periphery of the fluid cooler structure remains partly dry, seeing only random splash- ing from within the fluid cooler—plus normal atmospheric moisture from the entering air. Such lightly wetted areas are most subject to freezing.

Although ice is unlikely to cause structural damage, it may build up sufficiently to restrict the free flow of air. This effectively reduce the fluid cooler's thermal performance efficiency. When excessive ice forms, stop the fan for a few minutes. With the fan off, the action of the spray system will cause a slight downward movement of air through the coil and deice the fluid cooler.

Intermittent Wintertime Operation:

If periods of shutdown (nights, weekends, etc.) occur during freezing weather, measures must be taken to prevent the water in the cold water basin—and all exposed pipework—from freezing. Several methods are used to combat this, including automatic basin heater systems and pump freeze protection systems available from Marley.

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