An alternate system runs on the fog or fine mist injected into the intake air stream. Although several commercial systems are available, growers can assemble and set up their own system utilizing a high pressure piston pump and fog nozzles. The basic components are proven in Fig. 1. A two-stage system controlled by a two- stage thermostat enables more water to be applied on excessively warm, shiny days. Temperature settings should be 5-10°F apart.
Algae development in the pads can become a problem which will reduce the effectiveness of the machine and result in accelerated deterioration of the pads. The addition of an algaecide to the water supply will help in control.
It is desirable, especially in hard drinking water areas, to add a wetting agent to the drinking water to obtain additional uniform wetting of the pads. A commercial material or liquid household detergent at the price of 2 tablespoons per 100 gallons can be used.
Water for the pads should be clean and lower in mineral content to avoid clogging and coating of the pads. A pump, pipes and gutters are used to recirculate the water. A flow rate 113 gallon each and every minute per linear foot of pad system should be provided to assure adequate wetting.
In the most common coolant system (fan and pad), the fans draw air through wet pads that prolong the length of 1 endwall or sidewall. Aspen and coated cellulose are common pad materials that usually have life of one to three years. Approximately one square foot of pad are is necessary for 20 square feet of floor area.
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