The CIP system is actually a chemical cleaning operation, in which the chemical solution is brought into contact with all soiled surfaces. Addition of surface active substances, reducing substantially the surface tension of water, facilitates the penetration of water and aqueous cleaning solutions into crevices of the equipment. The required tanks, pumps, pipes, valves and heaters (heat exchangers or steam injection devices) are used either as single-use or re-use (re-circulation) systems. Air-operated piston or diaphragm-type pumps are used to feed the chemical solutions. For safety reasons, the pumps and the chemical supply containers are enclosed in a separate compartment of the processing plant.