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to the front. Generally speaking, ship- owners hesitate to pay for such an im- provement unless the underwriters will recognize this in fixing the rate of prem- ium. The underwriters, therefore, have it in their own hands to reduce, or entirely eliminate, their fire losses, by assisting in the way indicated in the general introduc: tion of reliable and efficieut fire-protcc- tion systems. The Gronwald Chemical Fire-Protec- tion System, with which the Adelaide is equipped, is an apparatus designed to ex- tinguish by the introduction of carbonic acid gas any fire which may have broken out in the holds or other compartments of a vessel, prevent spontaneous conibus- tion, and suppress the fire in its incipiencc. The carbonic acid gas is passed into the compartment or hold through perforated pipes fitted so that the gas is distributed to the best advantage, the apparatus recommended for use aboardship being portable and easily handled. The suppty of gas is stored in the ordinary steel drums or cylinders carried on vessels equipped with refrigerating plants, ves- sels equipped with the CO: system having merely to carry a larger stock of drums. To facilitate the flow of gas, steam is passed through the apparatus from the ship's boilers, the purpose of this arrange- ment being to heat the apparatus, aid in the expansion and flow of the gas, and prevent the formation of snow. No ex- pert knowledge is required by the oper- ator, the gas working under its own pressure and being ready at all times for instant use. For fire extinguishing pur- poses it is not necessary to entirely fill the hold or compartment with CO. gas, the admixture of a certain percentage of gas to the oxygen in the space being quite sufficient, depending on the nature of the burning material, and ranging from 10 to 25 per cent. Taking, as the outside limit, an admixture of 25 per cent., the Gronwald appliances are able to fill with even so high a percentage, in one hour's time, a space of 67,200 cubic feet, which means the contents of 48 steel cylinders of 40 pounds liquid COz each. The system is particularly adapted for the prevention of spontaneous combus- tion and ignition through its ability to dis- place the air from the hold or compart- ment and so cut off the supply of oxygen. Should the air in the hold reach an ab- normally high temperature, several bot- tles of liquid CO. discharged through the apparatus will displace the air, and, at the same time, by evaporating rapidly and depriving the surroundings of its heat, lower the temperature of the hold by 30 degrees or more. It is claimed the CO. system is the only chemical fire ap- plance capable of thus lowering the tem- perature where fire is threatening. Another point of superiority claimed for CO: is its ability to penetrate fibrous "'TAE Marine. REVIEW materials where water would fail, as in the case of cotton bales. Again, as is the case with fires on land, the damage caused by the water used in fighting the fire is often a much more serious item than that caused by the fire. The most delicate 25 cargoes cannot be affected by CO, gas, which is neutral, nor the fittings and decorations of the vessel. Lastly, it is pointed out that water cannot extinguish an oil steamer fire, though a chemical fire appliance can do so with ease. Note on the Use of Superheated Steam with Marine Engines BY MONSIEUR FELIX F. T. GODDARD.* Superheated steam was used in marine engines more than half a century ago, after Hirn's noteworthy experiments with the "Logelbach's" engine in Alsace. The French navy also tried it on some of their earliest protected cruisers. These early attempts were not, how- ever, followed up, as it was found diffi- cult to construct superheaters capable of maintaining a constant and_ sufficiently high temperature, and also because of the wear and tear of the hemp packings in use at that period. The introduction of compound marine engines, more economical than the simple engines that had preceded them, caused the use of superheated steam to be given up for the time being. The same thing occurred with stationary engines, where improvements in valve gear enabled a high ratio of expansion to be employed and the clearances to be reduced to a very . small percentage of the cylinder volume. In the Vosges and Alsace, however, the problem of using superheated steam in stationary engines was revived some fif- teen years ago. Several different arrange- ments were designed by Mr, E. Schwoer- er, a former assistant of Hirn's, who used 1600 showed this to be the case. Since then the use of superheated steam with stationary engines has increased largely, and considerable economy has been effected thereby. It is not unusual to find engines of 1,500 I.H.P. to 2,000 LHP. "using "steam at. 300° ©. (a72- Fahr.) and working at an expenditure of only 4 kgms. (9 /bs.) of steam per LHP 'per hour, There is but little information, how- ever, on the subject of the variation in the consumption of steam in relation to its temperature. A few years ago the author made some experiments on a triple-ex- pansion engine with piston valves, the temperature of the superheated steam varying from 0 to 120° C. The results of these trials still present some features of interest. In the accompanying dia- gram (Fig. 1.) the abscisse represent the amount of superheat, 7. e., the difference between the actual temperature of the steam (in degrees C.) and the temper- ature corresponding to the pressure when the steam is saturated. The ordinates represent the weight of steam consumed per effective brake horse-power. TRIPLE-EXPANSION ENGINE. Diameter of cylinder (H. P.) Diameter of cylinder (M. P.) Diameter of cylinder. CL. PP) 2408.24. 3.015.? Stroke Revolutions Power Cut-off Ratio of expansion Pressure in main steam pipe €A).......-...-- : Pressure in main steam pipe (B) A exhaust to atmosphere. B exhaust to condenser. ojo erie oicei9 pie 8 0616 fe 0 Pee. 8 cero. 8 ere ee oe. evelin testa, ple: 0: 0160) 0 0:6), 0010-6 (0.8.0. 0)0 0076 -e varie e610 1058 wooo: oe 0: Beha) of 0.0. 0.0 01100 eite. 0: 000° Je. 60:0) weve: w. oe © 0 6 we. e 0 e686 10 0.8, 00 v0.11: Cneryen.e 10-8 8 10) 0:00 0) 8 600 Raw igile 0 Weise a tele Sere W oo) 6 676. @: 16 Cie ace) 0 Sue te.6. 07.6 ee. 00 ee 0:20°-m:; (GH ina) eee oe 0:33° -m, (13: ins) teas 0.37 m. (149/16 in.) Seg 0:29 mm. GE 7/16" in.) Ree ee 440 ear ee 300 B; HP Sete ke es 0.7 see tle wale 9.8 : aa 12.8 kgms. (182 Ibs. per sq. in.) kgms. (214 Ibs. per sq. in.) a massive superheater placed behind the fire bridge of the boiler furnace, and this 'gave such promising results that the study of the question of superheated steam was taken up by a number of manufacturers, chiefly in Germany, Alsace, and Switzer- land. It was found that engines fitted with Sulzer Colman valves, which were largely employed in those countries, were very suitable for use with superheated steam. In France, where the Corliss gear was ustial in stationary engines, superheating did not make much progress, because it was not suited to the Corliss engine, or, in fact, to any flat slide valve engine. The exhibits at the Paris Exhibition of *Read at the spring meetings of the forty- ninth session of 'the Institution of Naval Architects. Now, curve A in the diagram (Fig. 1) (exhaust to atmosphere) shows that the consumption per hour of saturated steam (i, e,, with no superheat) is 8.85 kgms. (1914 lbs.) per B.H.P., whereas it falls to 5.70 kgms. (1234 lbs.) at a temper- ature of 320° C. (608° Fahr.), equivalent to a superheat of 120° C. (216° Fahr.). The saving therefore amounts to-- 8.85 -- 5.70 = 35.5 per cent. 8.85 Taking curve B (exhaust to condenser), the consumption per B.H.P. falls from 7.15 kgms. (16 Jbs.) with no superheat, to 4.85 kems. 10%4 /bs.) with a superheat of 120° C., or a saving of-- referred to in this paper is Aha GE Bs of 75 'kgms, = French "force de cheval" 0.986. British "TP: