CHAPTER XIV.
TANK HOUSE DEPARTMENT.
Tank House Design — Isolation and Ventilation — Separation of Press Room — Digesters — Rendering Tank — Surface Box — Press and Pump — Cooking Killing Stock — Operating Tank Blow Off — Pressing Tankage — Treatment of Lard and Tallow — Titer in Tallow and Lard — Steam for Cooking — Cooking Tests — Operating Odorless — Tests — Catch Basin.
Introductory.
—When slaughtering was done promiscuously throughout the country, sufficient product was not available at any one point to necessitate a tank house, consequently open kettles were used either with fire under them, or jacketed for steam, the best of the fat was thus rendered, and the balance was thrown away. It being impossible to render offal to advantage under these conditions, the “digester” as it is called by many, was evolved. It consists of a closed tank in which cooking is done at forty pounds steam pressure, giving a temperature of nominally 287° F., this high temperature thoroughly disintegrating all products in the tank, liberating all the grease. The residue from cooking in this manner, after being pressed, is dried and sold as fertilizer. The effectiveness of this process is shown, for instance, by the fact that if a hundred cattle heads are put into a tank, after cooking, the bones are entirely disintegrated, except the teeth.
Tank House Design.
—Almost any arrangement of tank, surface box and press can be made to serve the purpose of rendering. The method and arrangement shown herein are those practiced by one of the revisors of this work and embodies principles as described.
The requisite apparatus for a rendering or tank house consists of but few articles, viz: the rendering tank or digester, the surface or skimming box, and a press, but the design and operation is of such consequence that the same will be described in detail.
Isolation and Ventilation.
—The rendering building from its character should be isolated and arranged for ventilation on at least three sides. The United States sanitary requirements compel the complete separation of the edible from the inedible section by the use of separate buildings or a parting wall.
