jANl-ARV 1. 1920] 



THE INDIA RUBBER WORLD 



215 



(c) pRiriioN Tests. — Wherever practicable all tests shall be 

 made on an automatic friction testing machine; ply separation 

 being 1 inch per minute. Except in rubber-lined cotton hose, 

 width of test specimen shall be 1 inch. In all cases strength of 

 friction shall be the average value obtained on each test, and 

 be given in pounds. 



(d) Rubber. — Longitudinal specimens shall be taken on hose 

 and tubing under I'/i inches inside diameter; transverse speci- 

 mens on all others.. 



Test specimens shall be buffed smooth to approximately not 

 more than },s-inch in thickness and cut with a standard die hav- 

 ing a constricted part .'/2 by 2 inches, unless otherwise specified. 

 Tests shall not be made until sufficient time has elapsed for rub- 

 ber compound to recover from stretching or handling. 



AIR BRAKE AND SIGNAL HOSE AND GASKETS. 



War Department Specification No. 333-1-3 — June 6, 1919. 



(A) Aia BRAKE HOSE. (B) AIK SIGNAL HOSE. (C) AIR BRAKE AND 



AIR SIGNAL HOSE GASKETS. 



Gener.^l. — (a) This specification covers the requirements for 

 air-brake, air signal hose, and gaskets. 



(b) See War Department Specification No. 333-1-1, headed 

 General Specification for Mechanical Rubber Goods, which is 

 made a part hereof, except in such cases as the provisions below 

 directly conflict. In such cases the word and meaning of this 

 specification will govern. 



Construction. — See General Specifications. 



(o) Din.ensions to conform to the table below. 



(b) Cotton canvas layers shall be applied on a bias of from 

 42 to 46 degrees 



(c) Hose to be capped with same rubber compound as tube. 

 Id) Each length properly fitted with Master Car Btjilders' 



(MCB") staTidard air-lirake or air signal couplings, if specified. 



(<?) If coupled, coupling shall be put in end near which brand is 

 located. 



(/■) Gaskets must be uniform in size and section and of dimen- 

 sions conforming to figure 1. 



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USA. WVTEife 



11^ 

 '.< — 



-ift-f- ■ 





Fig. I. 



Br.^nding. — See General Specifications. 



(a) Hose.— A 1-inch side label shall be applied 6 inches plus 

 or minus J/j-inch from one end of base with the top of lettering 

 toward the center of the hose. Use the words, ".\irbrake" on 

 air brake hose ; and the words "Air Signal" on air-signal hose. 



(b) Gaskets. — See Figure I. 

 Materials.— See General Specifications. 



(a) Tne fabric shall be made of long-staple cotton having not 

 less than 16 nor more than 22 threads of 5-ply yarn per inch, 

 each in warp and filling, and weighing not less than 19.8 ounces 

 per square yard. 



(6) Gaskets shall be made of such a compound that they will 

 be tough and yet have enough elasticity to conform to the re- 

 quirements for strength and elongation. 



Inspection. — See General Specifications. 



(o) Inspector may take one length at random from each 

 shipment of 200 lengths or less of hose, from which he shall cut 

 a S-inch section. Two 1-inch sections shall be cut from this 

 5-inch piece for making friction, stretching, and tensile tests ; 

 the remaining 3-inch section shall be used for making additional 

 tests which may be desired on the tube and cover. 



(b) Inspector shall examine such lot of gaskets for size and 

 workmanship, and shall take samples therefrom for tests. 



Tests— See General Specifications, 

 (a) Hose. 



1. See the following table. 



2. Test samples not to be buffed. 



3. Stretching test. 



Test specimens from tube and cover will be quickly stretched 

 until the 2-inch marks are 10 inches apart and immediately re- 

 leased. They will then be remarked as at first within 10 seconds 

 after starting to release and again stretched to 10 inches between 

 the new marks, remaining stretched for 10 minutes. The speci- 

 mens shall then be completely released, and within 30 seconds 

 after starting to release the distance between the marks last ap- 

 plied will be measured, and the initial set shall not be more than 

 J4-inch. At the end of 10 minutes the distance between the 

 marks will again be measured, and the final set shall not be more 

 than J^-inch. These test specimens may be cut from the tube 

 and cover of the friction test specimen, but shall not be used 

 fgr tensile test, 



POROSITY TEST. 



The remaining 17 inches shall be mounted and placed in a test 

 rack, the circumference will be measured and the hose filled with 

 air at 140 pounds pressure per square inch, the rubber cover shall 

 be cut froiu clamp to clamp (taking care not to injure the duck) 

 and this pressure maintained for five minutes. At the end of this 

 time the hose will he submerged in water to determine whether 

 the inner tube is porous. The escape of air through the tube 

 shall be distinct enough so that the porosity will not be confused 

 with the escape of air which is confined in the structure of the 

 hose. In the event the hose fails on bursting test at the point 

 at which cut was made for porosity test and a satisfactory hy- 

 draulic test is not obtained, the porosity and hydraulic test will 

 be repeated on another piece of hose. 



The section of hose which was used for porosity test shall 

 also be used for the hydraulic tests. 



If the tensile strength in pounds per square inch is greater 

 than that required, the sample may be accepted providing the 

 per cent increase in elongation is equal to or greater than the 

 per cent increase in tensile in pounds per square inch above the 

 maximum figure. 



(6) Gasket. deelection test. 



Gaskets shall be subject to a deflection test which shall consist 

 of suspending a weight of 20 pounds on the gasket. Under this 

 load the increase in inside diameter shall not be more than Ji 

 inch, the measurement to be taken on the inside of the gasket 

 with the load applied, and within 15 to 20 seconds after the 

 application of the load, support, and the hook to which the 

 weight is attached, shall have a diameter of 14 inch. 



TENSION TEST. 



When the samples for test are received they will be examined 

 for size and workmanship. The gaskets will be tested in tension 

 in a manner similar to that of the tensile test of a single link of 

 a chain. The half-links used to pull on the gasket will each be 

 provided with 180 degrees fillet of the same diameter as the 

 original inner diameter of the gasket— that is, the two semi- 

 circular fillets of the pulling links will just fill the inside of the 

 gasket. They should sustain an ultimate load of 100 pounds 

 and show an elongation of original diameter of 350 per cent 

 when tested as described above. 



REJECTION LIMITS. 

 If any of the sample gaskets representing a lot should fail 

 under a load of less than 90 pounds, or if the elongation is less 

 than 200 per cent, the entire lot represented by the sample will 

 be rejected. If the tensile strength of any sample tested is more 

 than 125 pounds the lot will be rejected, unless the elongation 

 obtained from such samples is more than 275 per cent. 



Table. .\ir-br.\ke. .\ir Signal. 



Size, mininuim inches IH 1% 



Inside di.imeter, maximum inches I A 1 A 



O.ltside diameter, minimum inches 2^ 1 )J 



Outside diameter, maximum inches 2'4 1 ji 



Length, minimum inches 22 22 



Length, maximum inches 22J4 22!/; 



Thickness: 



Tube minimum inch »/m '/sj 



Cover, minimum inch -f^ -f. 



Cap, minimum inch Vs2 Va, 



Cap. maximum inch 'Aj >/,, 



Porosity test, minimum pounds 140 1-10 



Hydrostatic tests: 



Pressure, minimum pounds 200 200 



Increase in circumference, maximum inch H \i 



10-minutc test without bursting, minimum . .pounds 500 500 



IJursting, minimum pounds 700 700 



Tube, minimum pounds 800 800 



Tube, maximum pounds 1,200 1,:00 



Cover, minimum pounds 70O 700 



Cover, maximum pounds 1,100 1. 100 



Ultimate elongation, tube and cover, minimum .inches 210 2-10 

 STEAM HOSE. 



War Department Specification No. 333-1-11— June 6, 1919, 

 General.--(<i) This specification covers the requirements of 



