Abstract: A system for cleaning the tubes of a condenser or other heat exchanger unit by circulating sponge balls therethrough by a circulating pump, comprising the improvement in the form of a screen assembly including four vertical screens about 90.degree. apart, two of which confront the discharge end of said condenser to divert the sponge balls downwardly through an internally spiralled stationary tube, while the other two screens confront the discharge pipe of the system. By turning the screens 180.degree., they are completely flushed of debris without the need of removing the balls to an accumulator and stopping circulation of the balls during the screen cleaning operation. Higher efficiency, elimination of down time and lower maintenance costs are provided.

Abstract: A four-way valve powered by a single pneumatic power unit enclosed in a cylindrical portion which is detachably secured to a second cylindrical portion which encloses three or more pistons whose piston rod is directly connected to that of the power unit. An inlet port in the second cylindrical portion alternately discharges milk or other liquid through one of two outlet ports on the other side thereof, depending upon the position of the operating piston of the power unit. At the same time, inlet and outlet ports are open for the flow of a second type of liquid, such as cream, across the second cylindrical portion.

Abstract: A butterfly valve assembly particularly suitable for large size fluid-carrying pipes. Instead of using a unitary disc as the rotatable valve element, two offset half discs are provided, staggered by the diameter of a pipe or sleeve surrounding and connected to the shaft which is rotated to open and close the valve. Sealing half-rings connected to each half disc and projecting beyond their perimeters abut against a radially inwardly extending shoulder on an interconnecting pipe or housing between two confronting large pipe ends. Thus no rubbing of the sealing parts results and a positive seal is provided. Means are provided for access to the butterfly disc assembly for replacing the sealing half rings without taking the entire assembly from the line.