Iarch 1, 1913.] 



THE INDIA RUBBER WORLD 



297 



From a study of the relation of the service of air hose to 

 results obtained from tests of sample pieces, we draw the follow- 

 ing conclusions : 



1st — To prolong the life of hose from a possible bursting 

 failure a good friction is necessary. 



2d — The quality of the inner tube as determined by the stretch 

 test gives an indication of the probable life of the hose before 

 it fails due to deterioration. 



3d — That the outer tube merely serves as a protective coating 

 and the chief requirement is that it remain intact. 



digester must not disclose any swelling in diameter or increase 

 in thickness of the various parts and there must be no indication 

 of blisters or loosening of the inner tube. 



Data sheet "C" shows number of this hose removed during the 

 year from November, 1911, to November, 1912. The data show: 

 (1) the general causes for removal and (2) average life of hose. 

 The total number of hose of each make purchased is shown as 

 an indication of the proportion of the different makes in serv- 



STE.\M-HE.\T HOSE. 



The steam hose from which the following data are compiled 

 was of one size, 1% inch x 24 inches, used on passenger cars, 

 locomotives and tenders. All this is used with an automatic con- 

 nector illustrated under the discussion of air hose. The construc- 

 tion and shape of tliis hose are shown annexed. 



The essential points of the specification under which this hose 

 is purchased are that the sample piece is to be tested as follows : 

 A piece of the inner tube one-half inch wide cut circumferenlially 

 with the grip ends one inch wide, must show an elongation to not 

 less than six inches before breaking (between two marks that 

 have been placed two inches apart). The ultimate tensile strength 

 of this piece must be not less than 600 lbs. per square inch. The 

 friction of a section one inch wide must be such that the duck 

 will not start to unwind with a pull of less than 20 lbs. The 

 remainder of the sample is then placed in a closed vessel, known 

 as a digester, and su1)jected to dry saturated steam at a pressure 

 of 45 lbs. per square inch for a period of 48 hours. The hose is 

 removed from the digester and sufficient time allowed for it to 

 cool naturally. The tests are then repeated and the stretch test 

 must not show a deterioration of more than 20 per cent, while 

 the tensile strength and friction test must not show a deteriora- 

 tion of more than 30 per cent. 



Further, an inspection of the hose after its removal from the 



DATA SHEET 



PERFORM.^NCE 1% INCH X 24-INCH COR, 



Item ABC 

 Damaged in service .... 8 



•^.pi-t rocx- 



Ste/vm Heat Kose. 



STE.VM HOSE. 

 D 



E 

 7 



Per cent, of total 



2.43 



4.02 



G 

 1 

 33.3 



H 



Totals 

 16 



3.08 



Average life, months 



Total failures 



12^,53_ 

 327 



12.4 



174 



504 



Amount inspected 



400 



Amount acc epted 

 Amount rejected 



400 



1400_ 



_800_ 



600 



J00_ 

 400 



2200 



J^600 



600 



Per cent, rejected 



43.0 



27.0 



Average friction before and after digester test. ■ ■ ■ \ "" 

 Inner tube elongation from 2 inches before i 



25 lbs. 



23.7 lbs. 



27.3 lbs 24.3 lbs. 



17.5 lbs. 



and after digester test 



9" 



16.6 lbs. 

 8.2" 



_22^5 lbs. 

 8.5" 



18.2 lbs. 

 8.45" 



6.5" 



7.3" 



6.3" 



6.8" 



Average No. steam-heated cars operated in last two years 



Average No. steam-heated cars operated in 2 years previous to above 



Specification hose purchased in last 2 years 



Non-specification hose purchased in 2 years previous 



Specification hose used per car year 



Non-specification hose used per car year 



fThis hose considered only as to total consumption in last two years. No records as to tests. 



. 407 

 . 384 

 .2000 

 .3,300 

 . 2.5 

 ..4.3 



