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® Hose information is subject to change. For full details, visit our website or contact Customer Service. b. With some type of hose, it is useful to know how a hose will HOSE TESTING act under pressure. All change in length tests, except when performed on wire braid or wire spiralled hose, are made SAFETY WARNING: Testing can be dangerous and should with original length measurements taken under a pressure be done only by trained personnel using proper tools and of 10 psi (0.069 MPa). The specified pressure, which is procedures. Failure to follow such procedures might result normally the proof pressure, is applied and immediate in damage to property and/or serious bodily injury. measurement of the characteristics desired are taken and recorded. Percent length change (elongation or contraction) is the The Rubber Manufacturers Association (RMA) recognizes, accepts difference between the length at 10 psi (0.069 MPa) (except and recommends the testing methods of the American Society for wire braided or wire spiralled) and that at the proof pressure Testing and Materials (ASTM). times 100 divided by the length at 10 psi (0.069 MPa). Unless otherwise specified, all hose tests are to be conducted in Elongation occurs if the length of the hose under the proof accordance with ASTM Method No. D-380 (latest version). Where pressure is greater than at a pressure of 10 psi (0.069 an ASTM D-380 test is not available, another test method should be MPa). Contraction occurs if the length at the proof pressure selected and described in detail. is less than at 10 psi (0.069 MPa). In testing wire braided or RMA participates with ASTM under the auspices of the American spiralled hose, the proof pressure is applied and the length National Standards Institute (ANSI) in Technical Committee 45 recorded. The pressure is then released and, at the end of (TC45) of The International Organization for Standardization (ISO) 30 seconds, the length is measured; the measurement in developing both hose product and hose test method standards. obtained is termed the "original length." Many of the hose test method standards published by ISO duplicate c. Percent change in outside diameter or circumference is the or closely parallel those shown in ASTM D-380. Many are unique difference between the outside diameter or circumference and, in those cases, the RMA may be able to provide the necessary at 10 psi (0.069 MPa) and that obtained under the proof test standard references which may be purchased from the pressure times 100 divided by the outside diameter or American National Standards Institute (ANSI). circumference at 10 psi (0.069 MPa). Expansion occurs if the measurement at the proof pressure is greater than at HYDROSTATIC PRESSURE TESTS 10 psi (0.069 MPa). Contraction occurs if the measurement at the proof pressure is less than at 10 psi (0.069 MPa). Hydrostatic pressure tests are classified as follows: d. Warp is the deviation from a straight line drawn from fitting 1. DESTRUCTIVE TYPE to fitting; the maximum deviation from this line is warp. First, a. Burst test a measurement is taken at 10 psi (0.069 MPa) and then b. Hold test again at the proof pressure. The difference between the 2. NON-DESTRUCTIVE TYPE two, in inches, is the warp. Normally, this is a feature a. Proof pressure test measured on woven jacket fire hose only. b. Change in length test (elongation or contraction) e. Rise is a measure of the height a hose rises from the c. Change in outside diameter or circumference test surface of the test table while under pressure. The d. Warp test difference between the rise at 10 psi (0.069 MPa) and at e. Rise test the proof pressure is reported to the nearest 0.25 inch f. Twist test (6.4 mm). Normally, this is a feature measured on woven g. Kink test jacket fire hose only. h. Volumetric expansion test f. Twist is a rotation of the free end of the hose while under pressure. A first reading is taken at 10 psi (0.069 MPa) and Destructive Tests a second reading at proof pressure. The difference, in Destructive tests are conducted on short specimens of hose, degrees, between the 10 psi (0.069 MPa) base and that at normally 18 inches (460 mm) to 36 inches (915 mm) in length and, the proof pressure is the twist. Twist is reported as right as the name implies, the hose is destroyed in the performance of twist (to tighten couplings) or left twist. Standing at the the test. pressure inlet and looking toward the free end of a hose, a. Burst pressure is recorded as the pressure at which actual a clockwise turning is right twist and counterclockwise is rupture of a hose occurs. left twist. b. A hold test, when required, is a means of determining g. Kink test is a measure of the ability of woven jacket hose to whether weakness will develop under a given pressure for withstand a momentary pressure while the hose is bent a specified period of time. back sharply on itself at a point approximately 18 inches (457 mm) from one end. Test is made at pressures ranging Non-Destructive Tests from 62% of the proof pressure on sizes 3 inches (76 mm) Non-destructive tests are conducted on a full length of a hose or and 3.5 inches (89 mm) to 87% on sizes under 3 inches hose assembly. These tests are for the purpose of eliminating hose (76 mm).This is a test applied to woven jacket fire hose only. with defects which cannot be seen by visual examination or in order h. Volumetric expansion test is applicable only to specific GENERALINFORMATIONGENERALINFORMATION to determine certain characteristics of the hose while it is under types of hose, such as hydraulic or power steering hose, internal pressure. and is a measure of its volumetric expansion under ranges a. A proof pressure test is normally applied to hose for a of internal pressure. specified period of time. On new hose, the proof pressure is usually 50% of the minimum specified burst except for woven jacket fire hose where the proof pressure is twice the service test pressure marked on the hose (67% of specified minimum burst). Hydrostatic tests performed on fire hose in service should be no higher than the service test pressure referred to above. The regulation of these pressures is extremely important so that no deteriorating stresses will be applied, thus weakening a normal hose. 11