Abstract: An apparatus for dispensing a liquid detergent solution using a timing fluid is disclosed. A preferred cleaning system (10) includes a fluid-operated solvent metering apparatus (38). The metering apparatus (38) preferably includes a normally-closed valve (16) and a timing device (40). The timing device (40) preferably includes a cylinder (52) and a piston (54), wherein the piston (54) forms a pair of subchambers (56, 58) which are interconnected by a flow control device (68). The flow control device (68) serves to restrict the flow of a timing fluid from one subchamber (56) to the other subchamber (58) so as to hold the valve (16) in its open position for a period of timing following its initial manual opening. A return spring (48) in the normally closed valve (16) urges the valve (16) toward its closed position, and the spring (48) also acts against the piston (54) to cause the timing fluid to flow from the first subchamber (56 ) to the second subchamber (58).