Abstract: To control build-up of paint in the water tank an alkaline liquid containing NaOH is added in quantities to maintain a pH not substantially less than 9, thus preventing corrosion, and a hydroxide ion concentration not exceeding 0.01M. The additive is introduced by a metering pump under the control of a programmed timer over a seven day cycle. Over half the amount to be added in the cycle is introduced as a single discrete dose (preferably before a weekend) and the rest as smaller doses at intervals.

Abstract: A paint spraying booth has a back wall over which a water curtain flows to collect sprayed paint, a tank to receive the water curtain, vertical entrainment ducts disposed above the rear part of the tank, means for generating a flow of air through said ducts to lift water from the tank for the formation of the water curtain, a vertically-disposed wall separating the front and rear parts of the tank and having one or more transfer openings below the water surface, and baffle plates in the front part of the tank causing paint-laden water from the curtain to flow to a remote zone before returning to the transfer opening in order to minimize the quantity of paint passing into the rear part of the tank. A surface-removal device, preferably with a venturi unit, is arranged in front of the transfer opening to remove floating paint and pass it back to the baffled region for further dispersal.

Abstract: An immersion type metal degreaser for use with relatively low boiling fluorocarbon solvents or azeotropes thereof in which liquid solvent is boiled and vaporized in the degreaser by a heater immersed in liquid solvent which constitutes the condenser section of a compression-expansion refrigeration system and in which solvent vapors within the metal degreaser are confined within the degreaser by being cooled and condensed by means constituting the evaporator section of the refrigeration system. An adjunct of the cooling system maintains a portion of the liquid solvent within which ultrasonic units are immersed at the optimum temperature thereof.