BS EN ISO 1402:2021 pdf download – Rubber and plastics hoses and hose assemblies — Hydrostatic testing
Unless otherwise specified for the hose, the proof pressure shall be related to the maximum working pressure by the ratio given in ISO 7751. The test is not applicable to a curved hose. NOTE This text uses the term “maximum working pressure” instead of the deprecated term “design working pressure”. 8.2 Measurement of deformation under pressure 8.2.1 General procedure
22.214.171.124 Setting up the test piece When tests for determining change in length, change in outside diameter and twisting and/or warping are required, straighten the hose or hose assembly, lay it out horizontally for inspection and apply a hydrostatic pressure of 0,07 MPa (0,7 bar) approximately 5 min after completion of the proof pressure test. It is not necessary to apply 0,07 MPa (0,7 bar) when it is stable in keeping straightness without pressure. The supporting surface upon which the hose/hose assembly rests shall be flat and smooth enough to allow the hose/hose assembly to expand or contract without restriction. Alternatively, the hose/hose assembly may be supported on rollers or suspended vertically. When a section of hose is used as a test piece, it may also be placed in a test rig in a vertical position.
126.96.36.199 Reference marks For long hoses or hose test pieces (see 6.2), while maintaining the pressure, make three reference marks (A, B and C) on the outer surface, the middle mark (B) being made approximately midway along the length of the hose, and the outer marks (A and C) 250 mm (minimum) from B. Each mark shall consist of an arc on the circumference of the hose through which is drawn a straight line perpendicular to the arc, the three lines being co-linear (see Figure 1). For hose assemblies, measure the distance between the contact faces of the end fittings, or place the reference marks on the hose surface near the end of the inserted part of the fitting.
188.8.131.52 Measurement of initial dimensions At the initial state [no pressure or maintain pressure of 0,07 MPa (0,7 bar) for approximately 5 min], make the appropriate measurements (see 8.2.2, 8.2.3 and 8.2.4) at the reference marks A and C with an accuracy of ±1 mm using the measuring tape (see 5.3) and record these. Also, measure the external diameter or circumference accurately.
8.2.2Change in length at the specified test pressure
NOTE The test pressure is specified in the appropriate hose product specification and could be the maximum working pressure (see 8.1, NOTE), the proof pressure or any other pressure below the proof pressure at which the hose deformation characteristics are to be measured. Raise the pressure to the test pressure specified in the hose product standard at the rate specified in 7.2.2 and maintain it for 5 min (or longer when specified in the hose product standard). At the end of this period, measure the length between the reference marks A and C or, in the case of hose assemblies, between the contact faces of the end fittings, with an accuracy of ±1 mm, using the measuring tape (see 5.3) and record these values. The tolerance of the pressure is +10 % of the specified pressure. Calculate the change in length, Δl, expressed as a percentage (%) of the original length, from Formula (1):
l 0 is the distance between the reference marks A and C or the overall length (hose assemblies) measured at the initial state [no pressure or maintain pressure of 0,07 MPa (0,7 bar)], in metres (m);
l 1 is the distance between reference marks A and C or the overall length (hose assemblies) measured at the specified test pressure, in metres (m).
The percentage change in length, Δl, will be positive (+) in the case of an increase in length and negative (−) in the case of a decrease in length.BS EN ISO 1402 pdf download.