650 



THE INDIA RUBBER WORLD 



(&) Flexibiutv. — By flexibility is meant ability to bend with- 

 out kinking. When hose of internal diameter (Y) is bent around 

 a cylinder having diameter equal to (X) times the external diam- 

 eter of hose as in the following table, the external diameter of 

 hose shall not increase or diminish by more than 10 per cent. 



al diameter: 



(c) Dry Heat.— a 3-inch piece of hose shall be subjected 

 to dry heat at 132 degrees C. for two hours, and after cooling it 

 shall not be tacky nor show any tendency to crack. 



(d) Permeability.— (The specific gravity of the gasoline used 

 in this test should be between 0.710 and 0.725 at 15.5 degrees C; 

 65 per cent of it must distill over at 100 degrees C. from a dis- 

 tillation tlask when the bulb of the thermometer is jusj below 

 the side tube.) A 14-inch length of the hose is held vertically 

 and plugged at the bottom. 



The upper end is fitted with a glass tube about 18 inches long. 

 The hose so arranged is tilled with gasoline to a head of 12 inches 

 above the top of the acting length of the hose. The acting length 

 of the rubber hose is 12 inches. The upper end of the glass tube 

 is loosely closed with a cork. 



During the first 24 hours the level of the gasoline will fall com- 

 paratively rapidly. The loss of gasoline is made good by fre- 

 quent additions from a known volume of gasoline, care being 

 taken that the level of the gasoline in the glass tube does not fall 

 at any time by more than 3 inches. This test is to last for 72 

 hours, and the loss of gasoline during the third 24 hours shall 

 not exceed 100 c. c. per square foot of the original internal sur- 

 face of the hose. 



(e) Immersion in Gasoline— A 3-inch piece in the hose is 

 boiled for one hour (using a reflux condenser) in gasoline similar 

 to that used for the permeability test. The gasoline is allowed 

 to cool down. Twenty-four hours later the test piece is removed 

 from the gasoline and examined without delay, as follows : 



The internal diameter at the point of greatest constriction is 

 measured by means of rod gages. From this measurement the 

 area of the bore is calculated. It shall not differ from the original 

 by more than 25 per cent. 



The test piece is then cut longitudinally into halves, and the 

 adhesion between rubber and cotton carefully examined. The 

 adhesion shall be of such a character that the rubber can only 

 be stripped from the cotton bv hand with difficulty. 



(f) Immersion in Oil. — A 3-inch piece of the hose is im- 

 mersed in medium gas-engine cylinder oil at a temperature of 

 100 degrees C. for 8 hours, and for a further period of 24 hours 

 at ordinary temperature. The oil is then wiped from the surface 

 of the hose. The decrease of internal diameter shall be less 

 than 10 per cent. 



The flexibility and elasticity of the rubber shall not be dimin- 

 ished and there shall be no tendency of the rubber to separate 

 from the cotton. 



T.able II. 



JJD^-, O'S.— C-.-. C--. 0-1- o- 



Tolerance, plus or minus.. incli 1/16 1/16 1/16 1/16 1/16 1/16 



Tliickness: 



Tube, minimum ....inch 1/16 1/16 1/16 1/16 1/16 1/16 



Cover, minimum inch 3/64 3/64 3/64 3/64 3/64 3/64 



Fabric, plies, minimum 2 2 3 3 4 4 



Hydrostatic burst after gaso- 





.Ibs. 



160 



140 



140 



PNEUMATIC HOSE. 



War Department Specification No. 333-1-10 — June 5, 1919. 

 (A) BOCK-DEILL HOSE, (B) PNEUMATIC-TOOL HOSE. 



General. — (a) This specification covers the requirements for 

 pneumatic-tool and rock-drill hose for conveying air under 

 pressure. 



(6) 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 words and meaning of this 

 specification will govern. 



Construction. — See General Specifications. 



(o) Dimensions: See the following table. 



(b) The fabric plies of pneumatic tool hose shall be of sheet- 

 ing or a plain weave fabric. 



(f) The fabric plies of rock-drill hose shall be of duck. 

 Branding. — See General Specifications. 



(a) Use word "Pneumatic" on pneumatic hose. 



(b) Use words "Rock Drill" on rock drill hose. 

 Material. — See General Specifications. 

 Inspection. — See General Specifications. 



Tests. — See General Specifications and following table. 



(a) When test pieces are stretched 2 to 9 inches at the rate of 

 20 inches per minute, the stress upon the tube shall be at least 

 90(J pounds, that upon the cover at least 700 pounds per square 

 inch. 



Table I. 



Outside diameter inches 1 



!. D., plus or minus inch 1/64 



O. D., plus or minus inch 1/32 



Thickness: 



Tube, minimum inch 3/32 



Cover, minimum inch 3/32 



Fabric, plies, minimum 5 



Hydrostatic: 



Coupling test, minimum lbs. 250 



Burst test, minimum lbs. 600 



Tensile: 



Tube, minimum 



Ulti. 



.lbs. 



,300 



Tube and 



Permanent s 



Tube and 



utes. the 



Per cent s 



elongati. 



ver, stretch for 

 increase minimu 

 after 10 minu 



.inches 2- 9 

 '......' 25 



25 



25 



25 



SUCTION HOSE. 



War Department Speci«cation No.' 333-1-12— June 5, 1919. 



General. — (a) This specification covers the requirements for 

 hose used for the removal of water by means of suction pumps. 



(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. 



(a) Dimensions: See table following. 



(b) Smooth bore. — Shall be made with an inner rubber tube, 

 a helix of wire with rubber filling between the spirals; a second 

 layer of rubber ; cotton canvas layers ; and an outer rubber cover. 



Rough bore. — Shall be made with an inner helix of wire cov- 

 ered with a layer of cotton canvas; the spaces between the wire 

 filled with rubber in such a way that the cotton canvas is worked 

 inward, making the passage through the hose as smooth as possi- 

 ble ; a layer of rubber ; cotton canvas layers ; and an outer rubber 

 cover. 



(f) Suction strainers shall be furnished only when specifically 

 called for in the proposal. 



(d) The ends of each length shall be capped with the same 

 rubber compound as used in the tube. 



(?) The rough bore helix shall be of heavily galvanized flat 

 iron wire, with rounded edges ; the smooth bore helix shall be of 

 heavily galvanized or copperized flat or round wire ; each com- 

 plying with table. The spacing between the adjacent wires shall 

 be filled with rubber strips of the proper thickness and same 

 quality of rubber cotnpound as used for the tube. The rubber 

 strips shall be of suflicient thickness so that when the hose is 

 made up complete, the outside of the hose shall not show appre- 

 ciable corrugations. The helix shall end al such a distance from 

 the end of the hose that it will extend over the tailpiece of the 

 coupling about 1 inch when the hose is trimmed and the coupling 

 attached. The end shall be properlv secured and the space thus 

 left for the attachment of the coupling shall be filled with well- 

 frictioned cotton canvas layers of the same material as is used 

 in the body of the hose. The fabric placed under the wire at 

 the end of the rough bore hose shall not extend within the hose 

 more than S/J-inch beyond the end of the shank of coupling. 



Branding. — See General Specifications. 



(a) Use word "Suction." 



Material. — See General Specifications and following table. 



(a) Tube, cover, filler, layer, washers and friction shall be 

 properly vulcanized and contain not less than 35 per cent by 

 weight of fine Para rubber : not more than 3 per cent by weight 

 of sulphur, with the remainder suitable dry inorganic mineral 

 ;illers. 



Inspection. — See General Specifications. 



(a) With each lot of 50 lengths or less the contractor shall 



' See "Tf 



Rubber World." January 1, 1920. page 214 



