Equipment for Spray Systems Spray Washing Machines

Where metal is washed in volume on an assembly line, spray application of the detergent solution in an automatic or semiautomatic spray washing machine is the faster possible cleaning method. It combines the mechanical force of spray jets with the chemical and physical action of the cleaning solution.

Spray washing machines are usually engineered to a particular installation. Part, size, volume, time necessary to clean and rinse, and subsequent operations are factors that influence individual machine design. Many machines provide for more than one washing stage, as well as for rinsing and forced air drying. They can be batch cabinet style or in-line conveyor. The proper type is the one that matches the materials handling and product flow of the rest of the manufacturing process.

Work is transported through the various spray washer stages on a flat conveyor belt, in a screwlike drum that keeps work moving forward, or suspended from an overhead monorail. Spray machines deliver a solution through fixed nozzles, to impinge on work from all angles as it passes through. Soiled work is typically exposed to a detergent spray solution for about one minute, sometimes less.

For batch washers, the sprays can be either fixed or moving. Most operations have fixed sprays with a rotary table turning relatively slowly (usually 2 to 10 rpm) through the sprays to ensure overall cleaning. The use of programmable logic controllers in batch cabinet spray washers can allow multistage processing in a single cabinet. The key is to keep solutions separate and develop a system to prevent cross-contamination. This includes using separate spray headers or having a way to evacuate one solution before second-stage processing. If a dry stage is required, the cabinet must be designed so that the solution tanks can be closed off from the spray cabinet; otherwise, moisture will continue to flow into the cabinet. Parts will not dry in a wet cabinet.

Solution tanks should be sized to hold a volume of two to three times the pump flow rate. The tank bottom should be sloped for easier cleanout, and the entire tank should be insulated for efficiency and operator safety. The pump intake should be above the bottom of the tank and should be equipped with a screen to prevent the intake of sediment and chips. In handling unstable emulsions, pump intakes should be located at the interfaces of oil and water. In some applications, more than one intake is necessary. The reservoir tank is usually constructed of low-carbon steel. The thickness of the steel depends on the size of the equipment, but it should not be less than 10 gage.

0 0

Post a comment