(a) Aboveground containers comprising purifiers, clarifiers, and filters, in Class II systems shall not exceed 350 gallons individual capacity. Solvent storage tanks or Class II and Class III systems may be inside of buildings if individual capacity of tanks does not exceed 275 gallons and the aggregate capacity of storage tanks does not exceed 550 gallons. Quantities of solvents for Class II and Class III systems in excess of the above shall be in accordance with subchapter VIII of this chapter.
(b) The handling of solvents from storage tanks through the various machines and back to the settling and clear solvent tanks shall be through closed circuits of piping. Pumps shall be of positive displacement type and shall have a by-pass and relief valve.
(c) Sight glasses, the breakage of which would permit the escape of liquids, shall be of a type not readily damaged by heat and shall be reliably protected against physical damage.
(d) Liquid level gauge glasses in Class II systems shall be equipped with an automatic device which will immediately shut off the flow of solvent if the glass is broken. These liquid level gauge glasses shall also be guarded against physical damage.
(e) When underground treating and settling tanks are used a separate suction and discharge connection shall be provided to the pump for removal of sludge. The suction pipe shall be carried to the tank bottom, and the discharge connection to a suitable container.
(f) All piping shall be tested to a pressure of at least fifty percent in excess of normal operating pressure and proved tight and protected against physical damage.