A RECALCULATION OF CERTAIN DATA ON STEAMING TESTS 

 OF PHILIPPINE COALS 



By F. R. YcASiANo' 



So far as known, the only trials of the steaming qualities of 

 Philippine coal of which engineering data were kept for publica- 

 tion were made in the Insular Cold Storage Plant - and in the 

 Bureau of Science.^ In the latter paper many tests were given, 

 and I desire to present certain of the computations in a way 

 which in my opinion will make them more available. Cox 

 points out that the tests "are intended to be comparable only," 

 but this recalculation makes their direct comparison with 

 other similar results easier. Therefore, I will refer to the 

 various pages of that paper by using the letter "p" followed 

 by a number. 



In computing the area of the heating surface of a water-tube 

 boiler the outside diameter of the tube should be used,* because 

 the exterior surface is the part that comes in direct contact 

 with the hot gases. Therefore on p. 304, where both external and 

 internal measurements are given, the heating surface of the tubes, 

 recalculated on the basis of the former, is 6,393 square deci- 

 meters; that of the drum, 839.3 squai-e decimeters; and their 

 total area, 7,232.3 square decimeters; instead of 5,715.2, 748.8, 

 and 6,464.0 square decimeters, respectively, when the internal 

 measurements were used. This total area affects the ratio of 

 heating surface to grate surface (p. 304), which becomes 39.9:1 

 instead of 35.7:1. 



In the calculation of the factor of evaporation the temper- 

 ature of the feed water as it enters the water heater was used, 

 whereas the temperature of the water as it enters the boiler 

 should be used in computing this factor. The temperatures of 

 the water as it enters the boiler are given, and using these data 



' Mechanical and testing engineer. Bureau of Science. 



• Donovan, J. J., McChesney, D., and Williams, W. P., Far Eastern 

 Review, (1906), 2, 223. 



'Cox, Alvin J., This Journal, Sec. A (1908), 3, 301-356, 



* Tratis. Am. Soc. Mech. Eng. 19, 572. 



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