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60 "TAE. MaRINE. REVIEW MAIN ENGINE. MAIN EXHAUST CONDENSER MAIN FEED PUTIP BLACKBURN-SMITH FEED WATER FILTER AND GREASE EXTRACTOR FEED TO HEATER | £ AND BOILERS = _ PUMP DELIVERY TO ee GREASE EXTRACTOR FEED TANK x pa i J FEED SUCTION FROM TANK FIG, 3.--THE BLACKBURN-SMITH FEED WATER FILTER AND GREASE EXTRACTOR ON .SHIPBOARD. The Filter is located in the feed line between the feed pump and heater. pressure may be used to force the water through the filtering material. Where a closed heater is used the feed water should first pass through the filter, in order that the matter in suspension may not adhere to the sur- faces of the heater.and impair their heat transmitting properties. Where an exceptionally large quantity of water is to be filtered, it is quite an REPLACING THE FILTERING MEDIA. advantage to have a battery of filters, any one* or all of which may be placed in service orecut out at will. By having two filters one may be by-passed and cleaned, while the other goes on supplying the boilers with clean water. Referring to cross sectional view, fig. 2, of a Blackburn-Smith . filter, built by James Beggs & Co., of New York, water from the feed pump en- ters the inlet, passes into the upper or filtering chamber, through the fil- tering cartridges, into the bottom chamber and thence through the out- let to {he closed heater .or. boiler. The water passes through the cart- tidges with little friction, but, in the course of time, as the foreign mat- ter accumulates on the filtering ma- terial, some resistance will result. This resistance is shown by _ the reading of pressure gages connected to the filtering and outlet chambers. When the difference of pressure, as shown by the gages, increases to 20 pounds per square inch, the filter should be cleaned. A water relief valve automatically prevents the build- ing up of excessive pressure in the pump discharge line. All the main valves are on one stem and one movement of the hand wheel causes the filter to be put in operation or by-passed. The lower disk is double beat; and its position determines the flow through the fil- ter. The number of cartridges varies with the size of the unit. Each cart- ridge consists of two concentric cylin- ders of heavy perforated brass tubing covered with linen Terry. The fil- termg media conform to the shape of the cartridges, the closed end be- ing drawn down to a nice fit over the inner cylinder, reversed over the outer cylinder, and thé other end tucked in and clamped. by: a brass eap. This construction compels a double filtration so that any matter which gets through the first layer of Terry is sure to be caught in the second layer. Those who have worked in crowded plants or around the machinery of steamships or have kept big filtering tanks in order will appreciate the speed and comfort with which the filtering media of this type of filter may be changed when foul. The foul media should be boiled in water and soda so as to be ready for the next cleaning. The heavy impurities which may cling to the walls of the filtering chamber or settle to the bottom may be blown out by opening a_ sludge valve. The frequency of this, as of the other cleaning operations, varies according to conditions peculiar to each plant, and the cleaning periods are easily determined after a short operation. The capacity of such a filter varies according to the amount of surface of filtering material. In the Black- burn-Smith filter 7,500 pounds ' of water per' hour may be filtered through a 11-inch feed line, and the quantity increases up to 250,000 pounds per hour for a 6-inch line.