stiff flexible nozzle onto a metal grating above the liquid where the metal components rest. Dirt and dissolved heavy greases fall into the bottom and settle to the bottom of the tank. Originally, mixtures of oil distillates such as gasoline, diesel fuel, lacquer thinner or kerosene were used in solvent-based manually operated parts washers, but these are highly volatile and can ignite easily, potentially leading to an explosion and severe burns to the workers. For this reason, the solvent-based "tub" washer typically has a large cover that is propped open by a lead fusible link. In the event of a fire, the lead will melt and the cover will slam shut to snuff out the fire before it can cause further damage to the building... Aqueous-based An aqueous-based parts washer is much like a large dish washer. It uses water and detergent combined with heat and mechanical energy to provide the cleaning action. There are two main process styles of aqueous parts washers, the jet spray process and the power wash process. In a cabinet parts washer, the parts are placed on a turntable and the door is closed. During the cleaning cycle heated solution is flooded or blasted on the parts as the turntable rotates. Many systems have a wash, rinse and dry cycle. When the cycle is complete the door is opened and the parts removed. There are four primary factors that affect the cleaning results in an aqueous parts washer. These factors are mechanical energy, temperature, detergent and time. Adjusting any one of these factors in a cleaning cycle changes the cleaning results. A parts washer with large amounts of mechanical energy and a high temperature delivers shorter cleaning cycles and uses less cleaning detergent. Mechanical energy is provided by the pump drive system. Most aqueous parts washers use an electric motor to drive a centrifugal pump. The mechanical energy delivered to the wash load is what defines the mechanical energy for cleaning and not the horsepower of the pump. Efficient use of the pump motor energy through a well designed centrifugal pump and attention to details of piping design and nozzle types are critical to put the most mechanical energy into the cleaning process. Additionally, one must consider the work volume of the parts washer. In order to achieve similar results, from one size machine to another, the power density must be the same for a