M & L Suction Bells are, in effect, localized heating devices with piping connections arranged so that the oil is withdrawn and excess heated oil is returned through it. This combination of coil heating, using steam or hot water, and the return of the excess heated oil from the oil pre-heater and burner system, affords localized heating without wasteful heating of the entire tank contents.

 
In some instances, the return of hot oil, in itself, yields a sufficient source of heat so that the suction bells can be used without coils. They serve simply as focal points for tank connections and as reservoirs of heated oil returned to the tank from the pre-heater and burner system.

TANK OUTLET HEATERS INSTALLED IN THE OIL STORAGE TANK
For capacities beyond those obtainable with M & L suction bells, M & L tank outlet heaters are frequently used, being installed wholly within the tank. Ratings for tank outlet heaters can be obtained from our engineering department.

When tank outlet heaters are placed inside the oil storage tank they are usually installed through the manhole with the piping brought up through the manhole cover. The hot oil return, in such an installation, is brought to the open end of the heater, where it is immediately drawn into the heater for recirculation