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40 heating coil in the first-stage com- partment only, but under winter con- ditions it may be necessary to sup- ply additional steam to the second coil in the first stage and to the coil in the second stage in order to re- duce the viscosity of the oil and effect further separation. When the separator is in operation, the small quantity of oil remaining in the water after leaving the sec- ond stage is further reduced by ad- hesion to the crockery in the third and fourth stages, the particles of oil adhering tenaciously to the glazed surfaces of the pottery while the water passes through. Filters Are Scrubbed With Steam After the separator has been in operation for a considerable length of time, the pottery filters in the third and fourth stages are cleansed by “scrubbing” with steam. To ac- complish this cleansing the discharge valve in the water-outlet line is closed and_ sufficient water added through the inlet line to raise the water level within the separator above the “scum gutter” located between the third and fourth-stage compart- ments. The water supply is then cut off and steam admitted through valves 4 and 5. The steam passes through the pipe coils at the bot- tom of the compartments and out through small holes drilled in these pipes. The steam and hot water seem to have a scouring action which breaks loose the oil from the sur- face of pottery and causes it to rise to the surface. After the scrubbing action is completed, the valve in the drain line from the scum gutter is opened and the accumulated oil is drained, either into the second-stage compartment for further separation, or to the suction line of the pump. for repassage through the separator. Water may be added to the separa- tor to maintain the oil and water level above the scum gutter until the surface is thoroughly clean, but it is generally desirable to keep a _ thin film of oil over the surface of the water in the separator as this film seems to have an affinity for minute particles of oil which otherwise might he carried further into the separator. For testing the separator water from the Severn river was supplied through a 6 inch line by a centrifu- gal pump. The oil injection nozzle was located at one outlet of a tee in the supply line. Bunker A fuel oil was used during the test. The oil was run by gravity from the two large oil storage tanks to the suction oil storage tank, from which it was drawn by the injection oil pump MARINE REVIEW and passed through the oil meter into the water line. The oil discharged from the separator ran by gravity into the separated-oil storage tank from which it was raised by the sec- ond pump to the oil storage tanks. In conducting the test, oil was in- troduced into the separator at three different rates of flow, namely, 5, 25 and 50 long tons per hour. Runs were made at each of the three rates of flow with an oil content of ap- proximately 2, 5 and 10 per cent An overload run with 5 per cent oil content was also made. The above runs were made with a 1% inch by % inch reducing coupling screwed on the end of the 1% inch oil supply line. Runs were also made with full 1% inch pipe opening and with a noz- zle composed of 144 inch pipe capped at the end and helically drilled with sixty % inch-diameter holes. Two runs were also made to determine the efficiency of separation in the first two gravity stages as compared with the complete separation obtained with the entire separator. The data ob- served covered rate of water injec- tion, rate of oil injection, tempera- ture of mixture in, temperature of outlet oil, first stage, and tempera- ture of water out. Samples of in- jection oil, separated oil, and dis- charge water were taken on all runs, and on the last two runs samples of water at the end of the second stage were also taken. The oil samples were analyzed for water content and ‘the water samples for oil content. The negligible amount of oil in the discharge water is clearly shown by the analyses of the samples taken. The separated oil, when analyzed, was found to have a noticeable en- trained-water content which gradu- ally increased as the test proceeded. This water content was a result of continued recirculation of the injec- tion oil through the separator. It may be noted, however, that in gen- eral the increase in water content in the oil for a single passage through the separator was not over 4 per cent. It is interesting to note that even at rates of flow in excess of the de- signed capacity of the separator, the discharge water was, for all practical purposes, clean. The slight increase in oil content of the discharge water appeared as occasional extremely small globules which, when allowed to stand, would gradually rise to the surface of the sample and would barely form a connected oil film. The analysis of the water from the second gravity stage, runs 14 and 15, shows the effectiveness of the gravity separation as well as the ability of the tons per hour. October, 1926 filters to remove the oil which still remains in the water after passing the first two stages. No effort was made to measure the steam consumption, as very little was used. An estimate of the steam consumption for typical full-load con- ditions as obtained in one of the tests showed a steam consumption of 178 pounds at 15 pounds gage for a rate of flow of water through the separa- tor of 48.46 tons per hour and a rate of oil through the separator of 2.29 During the test many of the runs were made with steam on the heating coils only a portion of the time. The scrubbers need steam only at occasional intervals when it becomes necessary to clean the fil- ters. The scrubbing action of the steam seemed to be effective as was evinced by the amount of scum which rose from the filters. An Effective Separator From data and observations taken during the test, the following conclu- sions may be drawn: (a) The sepa- rator is very effective in operation within and slightly in excess of its rated capacity. (b) The steam con- sumption is low, and in some cases heating may be practically dispensed with. A thermostat-controlled valve would be desirable in place of valve 1, which, during the test, was man- ually operated. (c) The separator functions at any rate of flow within its rated capacity with no regulation or attention other than that required by the heaters and scrubbers. (d) The effectiveness of separation is de- pendent to some extent upon the in- timacy of the mechanical mixture of oil and water. (e) The separator ap- pears to function with mixtures of oil and water where a slight emulsi- fication has occurred, emulsified oil being separated out with other oil. Prohi bit Oil Pollu tion The board recently considered the question of oil pollution of navigable waters, which had been discussed at meetings of a committee made up of members from the different gov- ernment departments, which commit- tee was called “the inter-departmental committee on oil pollution of navigable waters.” Instructions were issued to. the president of the Fleet corpora- tion to take such action as he deemed practicable to carry out the recom- mendations of this committee in pro- hibiting shipping board vessels from discharging oil or oily mixtures with- in a zone of 50 miles from the coast of the United States. Effort is being made to stop oil pollution.