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Extinguishing oil tank fires with a blanket of foam
266
CURRENT TOPICS.
[J. F. I.
Application of a Polar F o r m of Complex Quantities to the Calculation of Alternating-current Phenomena. N. S. DIAMANT.
(Proceedings of the American Institute of Electrical Engineers, June 27-30, I916.)--In the calculation of alternating-current phenomena by means of complex quantities, as a rule, the rectangular components of the vector are used, and the rectangular form invoh;ing the operator j = ~,/2) is more common than the polar or exponential forms which involve the operators (cos 0 + j sin O) or ei0; although it is recognized that the latter are very convenient in certain cases. A simple method of dealing directly with the vectors themselves is described in the paper, and it consists in introducing the operator j", where n, contrary to ordinary usage, may be any positive or negative fraction. Just as j or jl rotates the quantity before which it is placed through I X 90 degrees, so j~ rotates the number into which it is multiplied through n X 90 degrees. The operator j" follows the rule of ordinary algebra, and, according to these, the different algebraic operations of multiplication, etc., are developed. A few illustrative problems are given, followed by a critical r(sumd. A summary of formulas and t)ibliography are included. E x t i n g u i s h i n g Oil T a n k Fires w i t h a Blanket of Foam. ANON.
(Scientific American., vol. cxv, No. 2, July 8, I916.)--There is only one effective way to extinguish an oil fire, and that is to smother it, in other words, to cover the burning oil with a suitable form of blanket that will completely cut off the supply of oxygen which is essential to combustion. In the protection of its oil tanks against conflagration the Standard Oil Company of California has met this requirement by developing a liquid extinguisher, which it calls " fire foam." Fire foam is formed by two separate liquors which, when mixed together, result in a thick spume, which readily spreads over a wide area and effectively shuts off the oxygen supply of the burning oil. The two liquids must be separately stored and brought together only just prior to the time when the foam blanket is desired in the blazing tank. The fire-foam liquors are led through a mixing pipe and discharged through tee heads above the surface of the oil at the centre of the tank, issuing from the outlets in the form of a thick liquid of creamy appearance. The foam rapidly spreads out over the surface of the blazing oil, bubbling as would a huge caldron of dense, boiling liquid. Here and there the flames are seen to reduce in size, eventually to be smothered entirely as the foam blanket becomes more dense. In the period of about a minute the fire is completely extinguished.
CURRENT TOPICS.
[J. F. I.
Application of a Polar F o r m of Complex Quantities to the Calculation of Alternating-current Phenomena. N. S. DIAMANT.
(Proceedings of the American Institute of Electrical Engineers, June 27-30, I916.)--In the calculation of alternating-current phenomena by means of complex quantities, as a rule, the rectangular components of the vector are used, and the rectangular form invoh;ing the operator j = ~,/2) is more common than the polar or exponential forms which involve the operators (cos 0 + j sin O) or ei0; although it is recognized that the latter are very convenient in certain cases. A simple method of dealing directly with the vectors themselves is described in the paper, and it consists in introducing the operator j", where n, contrary to ordinary usage, may be any positive or negative fraction. Just as j or jl rotates the quantity before which it is placed through I X 90 degrees, so j~ rotates the number into which it is multiplied through n X 90 degrees. The operator j" follows the rule of ordinary algebra, and, according to these, the different algebraic operations of multiplication, etc., are developed. A few illustrative problems are given, followed by a critical r(sumd. A summary of formulas and t)ibliography are included. E x t i n g u i s h i n g Oil T a n k Fires w i t h a Blanket of Foam. ANON.
(Scientific American., vol. cxv, No. 2, July 8, I916.)--There is only one effective way to extinguish an oil fire, and that is to smother it, in other words, to cover the burning oil with a suitable form of blanket that will completely cut off the supply of oxygen which is essential to combustion. In the protection of its oil tanks against conflagration the Standard Oil Company of California has met this requirement by developing a liquid extinguisher, which it calls " fire foam." Fire foam is formed by two separate liquors which, when mixed together, result in a thick spume, which readily spreads over a wide area and effectively shuts off the oxygen supply of the burning oil. The two liquids must be separately stored and brought together only just prior to the time when the foam blanket is desired in the blazing tank. The fire-foam liquors are led through a mixing pipe and discharged through tee heads above the surface of the oil at the centre of the tank, issuing from the outlets in the form of a thick liquid of creamy appearance. The foam rapidly spreads out over the surface of the blazing oil, bubbling as would a huge caldron of dense, boiling liquid. Here and there the flames are seen to reduce in size, eventually to be smothered entirely as the foam blanket becomes more dense. In the period of about a minute the fire is completely extinguished.