June 1, I9ll.] 



THE INDIA RUBBER WORLD 



323 



Average bursting pressure of 32 samples 700.37 pounds 



Maximum bursting pressure 975. pounds 



Minimum bursting pressure 475. pounds 



In only five cases did the bursting pressure fall Iielow 600 

 pounds to the square inch. In one case the coupling failed before 

 the hose burst. 



Fabric was commonly employed which contained unsightly and 

 injurious defects which should not have been allowed to pass 

 even the most superficial inspection at the factory. Marked 

 variation in the size of tlic fillers, uncvenncss in the tension and 

 distribution of the warps and fillers, numerous knots or splices 

 close together and considerable areas in which the weaving was 

 very uneven or in which the fillers were skipped by the warp 

 strands arc among the defects most frequently noted. 



The liehavior of the hose in the hydrostatic pressure tests of the 

 full length sections also indicated defects in weaving resulting 

 in excessive elongation, warping and improper direction of the 

 twist. Weakness due to the defects previously mentioned were 

 also brought out in tliese tests. 



The following is a summary of the results relative to fabric 

 obtained in the hydrostatic pressure tests of full length sections 

 at 300 and 450 pounds to the square inch. 



Elonc.vtion at 300 Pounds Pressure. 



Average elongation for all hose tested 49.1 inches 



Maxinuuii elongation of any length S1.S7 inches 



Minimum elongation of any length 21.87 inches 



The samples tested were not exactly fifty feet in length, but 

 did not vary from this dimension to any considerable extent. 



Twist at 300 Pounds Pressure. 



.Average amount of twist for all hose tested 85 turns 



Maximum amount of twist in any length 1.87 turns 



Minimum amount of twist in any length turns 



In two cases practically no tendency to twist was noted. Of 

 the balance, 20 samples twisted in a direction tending to tighten 

 and 11 samples twisted in a direction tending to loosen the 

 couplings. 



Warping at 300 Pounds Pressure. 



Average amount of warping for all hose tested 12.33 inches 



Maximum amount of warping in any length 45. inches 



Minimum amount of warping in any length 0. inches 



In only two cases did the hose show any tendency to rise from 

 the table and writhe. In several cases it was necessary to 

 straighten the hose and place it back on the tabic. The maximum 

 deflections from the original position are given in tlie above and 

 not the number of convolutions. 



Tests at 450 Pounds Pressure. 



Of tlie thirty-three lengths tested, three failed at or below 

 450 pounds pressure. 



In one of these the hose burst at 410 pounds, fifty-one and 

 twenty-seven filler strands being ruptured in the inner and outer 

 plies, respectively. Examination showed imperfect weaving at the 

 point of failure. 



In another case tlie warp strands in the inner ply started to 

 break at 400 pounds and were broken quite generally in this ply 

 at 450 pounds and to some extent in the outer ply. In this case 

 the fillers were apparently uninjured. 



In the third case the hose burst about three minutes after 450 

 pounds had been reached, seventeen and sixteen filler strands 

 being ruptured in the inner and outer plies, respectively. 



High grade hose fabrics possessing the requisite strength, wear- 

 ing qualities and flexibility must be made of a good grade of 

 cotton of fairly long staple. They should be even and firm in 

 texture throughout, and free from all defects which will weaken 

 the fabric at any point or result in unevenness in the surface 

 presented to wear. The weaving should be such that the elonga- 

 tion and tendency to warp out of shape will not be excessive 

 when the hose is under pressure and sufficiently well balanced 

 to prevent excessive twisting under the same conditions. 



Cement Backing. 



The defect next in importance and which was present in the 

 hose tested to a very marked extent, relates to the cement backing 

 and the influence this has on the character of the surface of the 

 waterway and consequently on the efficiency of the hose. In the 

 majority of the hose tested the backing was thin and insufficient 

 to properly fill the interstices between the fillers and reduce the 

 corrugations to a minimum. In many cases it was apparently of 

 inferior quality and did not provide a reliable and sufficient bond 



between the tube and the jacket. In one case the presence of 

 dirt and numerous cotton strands between the backing and the 

 fabric formed marked ridges in the surface of the waterway, 

 prevented good adlicsion and indicated carelessness on the part 

 of manufacturer. 



In many cases the lining was provided with heavy backing 

 from two to four feet back from the couplings and was fairly 

 smooth in those portions, the balance of the lining being badly cor- 

 rugated. 



The hydraulic friction loss was in excess of that allowable 

 for good hose in ten cases out of twenty-six samples tested. 

 In six cases it was excessive, amounting to over twenty pounds 

 per 100 feet with 250 gallons per minute flowing. At higher 

 velocities the difference l)Ctween the allowable loss and that olj- 

 tained in the tests of sucli hose generally increased quite rapidly. 

 The surfaces of the waterway of hose in which the friction losses 

 were 25.8 and 14.1 pounds per hundred feet with 250 gallons 

 per minute flowing. The allowalilc loss for good hose at this 

 rate on flow is about IS pounds per hundred feet. 



Average friction loss of 26 lengths tested 16.1 pounds 



Maximum friction loss in any length 25.8 pounds 



M iMinuini friction loss in any length 12. pounds 



Couplincs. 



The tests and examinations of the couplings attached to the 

 hose submitted show that this item is also commonly slighted not 

 only in regard to the quality of the castings and workmanship 

 but in the attacliment of the couplings to the hose. 



The average weight of the couplings for 2'/2-inch hose was 5 

 pounds 4.2 ounces, including the expansion rings. The maximum 

 weight for any set of couplings was 6 pounds 4.77 ounces, mini- 

 mum 4 pounds 10.18 ounces. In 14 cases the couplings were 

 overweight and in 13 cases they were underweight. 



The castings were not analyzed, but their color indicated that 

 the percentage of copper was low in eleven cases. In nearly all, 

 the tail pieces and expansion rings were shorter than specified 

 in the standard and in some the metal was not strong enough to 

 resist the stress of expanding tlie binding rings without rupture 

 or material distortion. In several cases the corrugations for bind- 

 ing the hose contained sharp projections due to sand left in the 

 moulds and in several cases the corrugations were sharp enough 

 to cut the hose fabric. 



The machine work was generally well executed and the cast- 

 ings well finished, but sufiicient care was not always exercised 

 in obtaining the proper thickness of metal in all portions. In 

 three cases the couplings were ruptured in the bursting tests of 

 three-foot sections, the male threaded ends being blown ofl 

 at 841, 617 and 542 pounds to the square inch, respectively. 

 Examination showed that the metal was less than 1-16 inch in 

 thickness at the point where the threaded portion joins the tail 

 pieces — a section entirely too thin to safely withstand possible 

 conditions of service. 



In one or two cases, couplings made by different manufacturers 

 were not interchangeable, although they were sold to the same 

 city. 



The couplings were attached to the hose so as to withstand 

 the 300 pounds pressure test without leakage in 17 cases out of 

 the 33, careless workmanship being generally responsible for the 

 defects. The most prominent defect resulting in leakage at the 

 couplings was the absence of or imperfect installation of rubber 

 washers between the expansion rings and tail pieces, although in 

 several cases where the washers were properly installed, the 

 rings were insufficiently expanded to make a tight joint. Liberal 

 leakage was noticeable past the tail pieces at pressures as low as 

 10 pounds to the square inch and sweating through the fabric, due 

 to leakage around the ends of the hose, was noted as far as 13 

 feet back from the couplings. Where the couplings were tight at 

 300 pounds they were usually tight at 450 pounds to the square 

 inch. 



The cotton fabric was doubled back in the coupling in many 

 cases and was quite badly cut by the corrugations in several in- 

 stances. The internal diameters at the tail pieces of some coup- 

 lings were too large and the rubber linings were cut part way 

 through by the expansion rings in quite a number of cases. 



Loosely fitted gaskets were employed in many of the couplings. 

 These were forced back into the recess in the swivel at pressure 

 as low as 90 pounds to the square inch, causing bad leaks in 

 almost every instance. The gaskets projected into the waterway 

 in most all of the couplings, amounting to 1-32 to 1-16 inch at all 

 points in many instances. 



From the foregoing it will be seen that the fire hose now being 

 received by fire departments throughout the country is not by 

 any means all that it should be. 

 The present general practice of purchasing hose by "brand" 



