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THe Marine REVIEW 138 SUMMARY OF INDICATOR CARDS. SATURATED STEAM. ' : ae a Mean effective pressure. Water Date. Time." zy : |. per. OP a alae ee see: eae SL ae hour, Oct. rr, | 2:15 (| aad | | Heo | ake | ise | 448 2200. 2 75 37.0 1255 11.5 oe 3:15 : 3:30 3 75 37-5 12.0 Th 4:00 | 4 75 38.0 13.0 179 so Atl . : ) nen i 86 40.0 13.75 aOO aaar 4:45 ' Averages,......... 78.2. a9. 12.85 £2:1 2997 Collective I.H.P., 512.34. SUPERHEATED STEAM, 57 DEGREES. Date. : eS Mean effective pressure. Water I Time. a pe a aio H.P LP, HL.P. | A,L.P. | Bour. Oct. 14.| 2230 2:35 I 78.5 37.0 13.25 12.25 2:55 2 84.0 37-5 13.25 12.25 3:15 3 81.0 27.5 13.00 12.25 ' 3:30 571 B36 A 70:5 33.0 11.50 11.00 3:55 5 80.5 37.0 13.25 12.25 4:15 6 75.0 3270 11.75 11.85 4:30 8,290 AVCTARES .....45. 78.25 36.5 12.67 11.98 | 8,430 : Collective I.H.P., 495.2. SUPERHEATED STEAM, $8 DEGREES. Date. = : Mean effective pressure. | Water Time. is ee a per fg & ) up Pe ee a eo Oct. 14.) 9145 : | -- 9:55 I 89.0 a6 ¢ 12,00 11.50 10:15. 2 85.0 33.0 11.66 10.125 10:35 4 91.0 37.0 12.50 11.50 F049 : | 7,965 10:51 4 95.0 37.0 12.50 12.00 Tris Ss 95.0 37.0 13:65 12,60 11:35 o 87.5 37:0 12.10 12.00 11:45 3 eq pes 8,291 11:55 7 85.0 36.0 1.75 12.50 12:15 8 85.0 35.0 12.50 12.25 12:35 9 90.0 36.0 13.00 12,50 rea 8,447 Averages......... 89.17 36.0 12,63 11,89 8,234 Collective I.H.P., 521.14. e at hand to secure a lower degree of superheat than 57 degrees. In the test with saturated steam, the superheater was completely cut off from the steam line and vented to the atmos-_ phere. The saturated steam was shown to be dry by a throttling calorimeter. The results obtained are shown in the following tables and, in the form of a curve, in Fig. 5. It will be noted that the water consumption of the main en- gine and auxiliaries was 18.3 lbs. per 1. H. P. per hour with saturated steam, and 15.5 lbs. when steam superheated 105 degrees was used. Expressing these results as heat con- sumption per I. H. P. per minute we have, respectively, 365.7 and 326.9 B. T. U's. That is, the heat consumption with 105 degrees superheat is 89.4 per cent of that when using saturated steam. In other words, the tests indicate that there is a net gain of 10 per cent obtained by using 100 degrees Fahr. of superheat. This may be expressed as a saving in coal of 1 per cent for each 10 degrees of superheat. The foregoing tests. conclusively prove the economy resulting from the use of superheated steam. In the following April, 1919 table, "Summary of. Tests," is found the > -actual saving in steam per indicated horsepower .for different added incre ments of superheat. These results are plotted in Fig. 5, and the gross Saving is found to' be 7.1 per cent when super. heating 57 degrees Fahr. and 15.3 per cent when superheating 105 degrees Fahr. The tests are directly comparable jp the saving of steam due to superheating, as the work done by' the main engine and its auxiliaries was practically con- stant, the exhaust steam being condensed and carefully check - weighed hourly. throughout the duration of the trials, Where there are relatively large losses from condensation the gain due to the use of stiperheat will be even higher than here shown. .This will be the case when running at low powers; so that for the ordinary cruising speeds of nayal vessels a gain of about 12 per cent in economy may be expected with 100 de- grees superheat. CONCRETE BARGES FOR PANAMA. According to the Canal Record, the official chronicle of the doings in the Panama zone, work will shortly be begun on the construction of three concrete barges to be uséd in sup- porting the dredging pumps for the hydraulic excavating and pumping plant of the Pacific division of the Panama canal. They. will be built near the: site of the hydraulic pumping sta- tion at a point on the canal nearly opposite Corozal. Each of the barges will be 64 ft. long by 24 ft. wide, and will have a depth of 5 ft. 8 in. The interior beams and columns will have a spacing of 10 ft. longitudinally and 8 ft. trans- versely. Wooden forms will be used in their construction and the barges . will be launched sidewise. Two in- terior longitudinal walls will extend throughout, with a bulkhead at each end, forming an interior compartment 40 ft. long by 8 ft. wide. The interior form will -be built in collapsible sections, so that the latter can be fe- . moved readily as the work advances. The frames for the hull will be con- structed first, and the preliminary work will consist of the erection of supports on which wooden forms will be placed. The wall construction of one layer of ™%4-in. mesh No, 12 wire cloth; %-in. transverse rods spaced 8 in. on centers, and 14-in. longitudinal rods spaced. 12°-in. -on "center; all securely fastened to the reinforced concrete frame work described above. The side walls and bottom of the barge will then be formed by laying will consist