A grease trap should be located as close as possible to the sink from which it receives the discharges. It should not be placed in the kitchen, however, on account of the offensive odors that would enter the room every time the trap was opened to remove the grease. In detached dwellings, grease traps usually are made of brick and placed outside the house. A better practice is to make the trap of iron and locate it in the cellar or basement, safe from frost and close to the source of grease.
Grease traps to be effective must have at least twice the capacity of the greatest quantity of greasy water likely to be discharged at one time into them. This is so that the entering water will be chilled and the grease congealed and rise to the surface of the water, thus being retained in the trap. If grease traps are too small, part of the entering water will pass through the outlet into the drain before it is sufficiently cooled, carrying with it whatever grease it holds in suspension, which will adhere to the pipes. In ordinary residences, a dish pan full of greasy water is the greatest quantity likely to be emptied at one time, and if the grease trap is made to hold at least twice that quantity, it will fulfill all requirements. In hotels, clubs and other large institutions where a great many people are fed, the probable amount of greasy water liable to be discharged at one time must be approximated, and the grease trap made with a capacity of twice that amount.
There are two types of grease traps in use: An ordinary trap with large intercepting chamber, as shown in Fig. 44, and a water jacket grease trap, Fig. 45, around which cold water circulates to chill the water in the trap. The water for this purpose is taken from the cold-water supply pipe, and must pass through the water jacket of the grease trap before being drawn from a faucet. When a water supply pipe is connected to a grease trap for this purpose, it should be continued to some unimportant fixture, or else connected to the hot-water tank, as water that passes through a grease trap jacket absorbs heat from the water within the trap and becomes disagreeably warm for most domestic uses.
Blow-off Tanks for boilers
High pressure steam boilers should never blow off or exhaust directly into a drainage system, but should first pass through a cooling tank that will condense the steam and cool the water to a moderate temperature. When live steam is discharged directly into a drainage system the steam heats the water in traps, causing it to vaporize and emit a disagreeable odor within the building. Also, if the system is constructed of cast iron with lead calked joints the expansion and contraction of the lines will work the lead calking out of the hubs and cause the joints to leak.