The present invention pertains to tank fittings, and, in particular, to a tank fitting utilized to provide a tank or vessel with an inlet/outlet port.
Tanks are utilized to transport and hold a variety of fluids. Tanks made of plastic frequently are either roto-molded or blow molded, and during each of these fabrication processes, molding openings into the tank is problematic. In order to provide a drain outlet in such tanks, typically a hole is drilled through the plastic tank body and a fitting is secured over the tank hole. To maximize the amount of fluid within the tank which can be drained by gravity, and if possible, such fittings are provided on the tank bottom wall rather than a tank side wall.
One problem with existing fitting designs results from the need to mount within the volume of the tank a back plate fitting part for connection to an externally accessible portion of the fitting. The use of conventional back plates limits the amount of fluid that can be drained from the tank. In particular, in order to drain from the tank, fluid must pass over the top edge of the back plate, through the back plate's central opening aligned over the hole in the tank wall, and then out through the external portion of the fitting. Consequently, any fluid in the tank at a height below the top edge of the back plate remains in the tank after drainage. An attempt to address this problem includes a low profile back plate fitting portion, but a better solution is desired as fluid still remains within the tank with such a design.
Another problem with many tank fittings results from the corrosive nature of the contents of the tanks. Frequently, the tank fittings are made of an inert material which does not react with the tank contents. However, stainless steel bolts, which simplify the interconnection of the back plate fitting portion with the external portion of the fitting, may react with the tank contents. To address this problem, threaded studs that are not exposed within the tank have been utilized. However, besides being more expensive to manufacture than bolts, such studs increase the assembly time, and therefore the assembly costs, of the fittings in which they are employed.
Thus, it would be desirable to provide an apparatus which overcomes these and other shortcomings of the prior art.