Inlet Header.
—For usual purposes steam and water are admitted into the tank at one point and steam at one, see Nos. 12-a and 12-b on diagram. If tank water is being collected and evaporated, line 12-c is introduced and used as follows:
Ordinarily the use of 12-b is for admitting water into bottom of tank in case the oil line after tank contents are cooked and settled are below the draw cocks.
In the event tank water is being saved to avoid weakening tank water by introduction of cold clean water, this result is accomplished by pumping tank water into the tank via the connection 12-c. If tank water is not being evaporated, 12-c line and connection is omitted.
Draw Down Pipe.
—If the oil is high and water appears at the draw-cocks 14 and 15, then the content is lowered by opening cock No. 13 and lowering the body as much as required.
Oil Draw Cocks, 14 and 15.
—When the tank is cooked, oil settled and the tank raised or lowered by use of No. 12 connections or No. 13 cock, the oil belt should be such that the bottom of it is about on a line with cock 14, and the main body of oil is drawn through cock No. 15.
Surface Box Treatment.
—After the oil is drawn out of the tank, the residue is dumped into the surface box. Anything that has not been thoroughly cooked will float on top in the vat. These floaters should all be skimmed off and put back into the tank to be re-cooked. The contents should be thoroughly agitated with a pole or rake, cooked fifteen minutes, allowed to settle and the oil carefully skimmed off. This should be done two or three times on each vat so as to free all the oil possible.