where R per cen. of cream obtained, ƒ = per cent fat in milk, fi = per cent fat in skim-milk; or where F per cent of fat in butter, B = yield of butter from 100 lbs. of milk, A = percentage churning. Under ordinary conditions of creaming these formulas may be simplified to ƒ2 = 6.67ƒ — 1.42, Formula for finding the per cent cream to be separated when a certain fat content in the cream is wanted (Fleischmann): f, fi, and fa = per cent of fat in full milk, skim-milk, and cream, respectively. HANDLING AND CARE OF CREAM SEPARATORS. By J. D. FREDERIKSEN, Little Falls, N. Y., Manager Chr. Hansen's Laboratory. In selecting a separator, local conditions, space at disposal, nearness to its manufacturer who can put it up, be held responsible, and quickly attend to repairs, etc., may be of importance, and the following points should be considered: Thorough Separation. All manufacturers claim that their machines do perfect work, but they do not always come up to the claims. Under normal conditions the measure for thoroughness of separation is the contents of butter-fat in the skim-milk as ascertained by the Babcock test. The best modern separators skim practically absolutely clean, and there is now no excuse for anything but perfect skimming. With normal milk at the proper temperature run into the machine at the rate of the capacity claimed for it, no separator should leave more than 0.1% of butter-fat in the skimmilk, which is the smallest percentage that can be ascertained by the Babcock test with accuracy. The table below gives the grand averages for the percentages of fat found in the trials of a number of the leading separators, conducted at the experiment stations of Delaware, Cornell (N. Y.), Vermont, Pennsylvania, and Wisconsin. With the constant improvement in machines it is not difficult to find separators which will do perfect work. Simplicity, durability and safety of coustruction are considerations of vital importance. The separator must be simple in construction so as to be easy to handle, to clean, and to oil. It must be durable, so that it will need but few repairs, and, first of all, it must be absolutely safe. Too many deplorable fatal accidents are already due to bursting separator bowls, and too much stress cannot be laid on the demand that the machine must by strongly built, of firstclass material and workmanship, so that accidents are made impossible with reasonably careful handling. As the pressure on the circumference of the bowl increases with the square of the speed, it is evident that the modern high-speed separators are exposed to a tremendous strain -in fact the tensile strain in some of them is as high as 20,000 to 30,000 lbs. to the square inch. Fortunately, the improvements in bearings and other features of construction which have enabled manufacturers to increase the speed, have caused them at the same time to reduce the diameter of the bowl, which makes the modern machine much safer than the first crude and heavy separators. Power.-Considering its capacity, a well-built separator requires comparatively little power, whether coal or muscle. But as either is money, it is a matter of importance that none be wasted. Many so-called hand separators are altogether too heavy to run by hand, hence in selecting one see that it is easy to keep it running for several hours. The tests made at the experiment stations by dynamometer, as well as by measuring the steam consumed, show that there is a great deal of steam wasted in a creamery above that actually required to drive the separator; that "the turbines use steam extravagantly, but that the small engine of the creamery uses it still more extravagantly." Due allowance must therefore be made for this waste in comparing results obtained by various methods of testing. The following table gives some of the results published by the stations: Horse-power per 1000 lbs Milk. These tests are made with single machines and do not guarantee that all separators of the same makes consume the same power or steam. The accumulating results of such trials being compiled, however, become a guide in estimating the value of the various machines in the market. As between belt and turbine (or direct steam) power, the former is preferable in large creameries. small plants one is about as economical as the other, and the choice may depend upon whether an engine is needed for churning, butter-worker, pump, and other purposes, or you can do without it. In Capacity. In selecting a separator it is best to have plenty of capacity. In a large creamery it is better to have two separators of moderate size than one very large machine. Only in very large creameries may separators of largest capacity be preferable. The capacity should be such as to finish the day's work in 4 to 6 hours at the time when there is most milk. In the private dairy, using a hand separator, the work should require only one hour, rather less. capacity: The following would be our idea of the proper Condition of Cream.-As discharged from the separator, the cream should be smooth and even, free from froth and of perfect "churnability." As to cost, the best machine is always the cheapest in the long run. Repairs, waste of fat in the skim-milk, of oil, and of coal, by an inferior machine, will more than make up any saving in first cost. |