Oil tank skimming device

Claim 1

In combination with a vertical cylindrical storage tank having a manhole entry near the bottom thereof, a skimming apparatus for removing water immiscible liquids of specific gravity below one from the tank, said apparatus comprising (1) a vertical flange of shape adapted to be fastened to, and to cover, the lower part of said manhole entry, with an aperture in the flange to permit free flow of liquid through the flange from inside the tank, (2) a receiving vessel fastened to the flange outside the manhole entry below the aperture to receive liquid flowing out of the tank and to conduct same to storage or other disposal, (3) an elongated open trough having level sides of uniform equal height below the level of the top of the vertical flange and with one end fastened to the flange at the aperture to permit flow of liquid by gravity from the trough through the aperture to the receiving vessel, said trough also having (a) a closed end remote from said flange, (b) dimensions to permit its insertion into and removal from the tank through the manhole entry, and (c) adjustable support means near said remote end adapted to support the sides of the trough in a fixed level position throughout their entire length, and (4) means to admit water to the storage tank below the level of the manhole entry at a rate to float the immiscible liquid and thereby force it to overflow the sides of the trough and flow by gravity out of the storage tank through the aperture in the flange into the receiving vessel.