Filter Press.
—The filter press ([Fig. 158]) should not be used more than two or three times until it is taken apart, all the sediment and dirt removed and clean cloths substituted. Continued use of filter cloths, without proper cleaning, has a deteriorating effect upon the material pumped through the presses, and different kinds of products should not be passed through the same press.
Color and Roll Treatment.
—Color is an important feature of compound, when an odorless oil has been produced. The mixture passed to the rolls is usually at a temperature of 120° F. and this heated body of material amounting to 4000 pounds per hour on an eight foot roll requires a very large capacity of refrigerating equipment.
It is desirable to maintain a brine temperature in the shell of from zero to five degrees above. A fifty-ton refrigerating equipment of commercial rating is inadequate for this duty. Consequently compound manufacturers must have ample refrigerating machine capacity.
The lard roll is preferably of the size noted and should operate at not to exceed seven revolutions per minute, provided brine of the above temperature is supplied; fewer revolutions if temperature is higher, which naturally reduces the capacity.
The lard roll, pump, and strainer equipment is the same as described for lard, except that the lard is packed directly from the picker trough without the use of an additional agitator.
Hydrogenation of Oils.
—A new process has been devised whereby soft oils, such as cotton seed oil, can be hardened so as to make a purer vegetable product. The substance has quite a large field but it is not intimately connected with the packing business.