=Defrosting.=--To dispose of the accumulation of frost that collects on the coils within the coil bunkers over the beef and hog coolers, it is usual to have a warm brine arrangement consisting of an independent feed header, cross connections to the coils, a tank containing a heating coil and a small pump. When the frost collects so as to be detrimental, a supply of brine in the small storage tank is heated to about 60° F., and it is continuously pumped through the small auxiliary header, thence into the coil it is desired to remove the frost from, until the frost is loosened, when it is lightly tapped and falls to the floor of the bunker pan. Unless the cellar temperatures are carried low it is unnecessary to use this system in the curing cellars, as the coils will drip from natural melting. The use of this system of brine installation with a proper defrosting arrangement has much to recommend it as to economy and efficiency, particularly in use with a balanced brine system. =Later Practice.=--A better system superseding that just described is to arrange the coil loft or cooler coils with a brine drip over them to remove the frost, the drip being collected in the pan, conducted to a reservoir and re-circulated. Similar to the manner used with direct expansion piping. =Gardner Curtain System.=--One of the early types of open brine chilling was the Gardner curtain system. For this system a refrigerator or curtain room is provided, directly above the meat coolers, and of same length and width, in which is fixed an open pan or brine distributing trough, located over the sheets and distributing the brine thereon. Fig. 28 shows a photograph of the curtains in a refrigerator or bunker room. A plan of installation showing position of curtains is given in Fig. 29, and Fig. 30 shows a cross section of a bunker room with the arrangement and insulation in a wood constructed building. =Direct Expansion Piping.=--There is a decided opinion among many operators that direct expansion ammonia system piping, is preferable over any brine circulation system, owing to the non-requirement of pumps for circulating purposes. Caution is necessary in erecting all direct expansion piping. It must be amply and securely erected, avoiding the use of coach-screws or lag-bolts, owing to the danger of rotting and giving away, thus causing perhaps fatal injuries. Room piping will appear best situated when grouped over alleys and arranged with drip pans so located as to avoid drip onto meats or packages. The ratio of piping given for brine pipe will hold as to lineal feet, substituting foot for foot of two-inch instead of three-inch pipe. [Illustration: FIG. 29.--PLAN OF GARDNER “CURTAIN” SYSTEM OF REFRIGERATION.]