ISO 6801:2021 pdf – Rubber and plastics hoses — Determination of volumetric expansion

ISO 6801:2021 pdf – Rubber and plastics hoses — Determination of volumetric expansion.
1 Scope This document specifies a method for the determination of the volumetric expansion of rubber or plastics hoses under hydrostatic pressure. This document does not specify the dimensions of the test piece and the test pressure(s) as each of which is specified in the appropriate specification. 2 Normative references The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 1402, Rubber and plastics hoses and hose assemblies — Hydrostatic testing ISO 8330, Rubber and plastics hoses and hose assemblies — Vocabulary 3? Terms? and? definitions For the purposes of this document, the terms and definitions given in ISO 8330 apply. ISO and IEC maintain terminology databases for use in standardization at the following addresses: — ISO Online browsing platform: available at https:// www .org/ obp — IEC Electropedia: available at https:// www .electropedia .org/ 4 Apparatus 4.1 See Figure 1. The apparatus comprises a suitable source of fluid which can be maintained at the required pressure, together with pressure gauges, piping, valves and fittings, so that a vertical length of hose can be subjected to hydraulic pressure. A graduated burette of sufficient accuracy is also required for measuring the volume of fluid corresponding to the expansion of the hose under pressure.
6 Procedure 6.1 Carefully connect the test piece in position on the apparatus in such a way as to obtain a leak- proof seal, taking care to avoid twisting it. Maintain the test piece in a vertical position without being in tension while under pressure. The free length of the test piece should be measured. 6.2 Fill the tank (1) with distilled water, taking care that it is free of air or dissolved gases. Open valve A (2) and fill the pressure source (4) with liquid. Open valve B (5) and partially open valve C (7) and allow the liquid to run from the tank through the burette (8) until no air bubbles are seen in the burette. NOTE Removal of air bubbles can be facilitated by moving the test piece back and forth. 6.3 Close valve A (2), C (7) and D (9) and raise the pressure in the test piece (6) to the test pressure and maintain for 10 s. Check for leaks at the connections and release the pressure completely in the test piece by opening valve C (7), which shall then be closed before proceeding as described in 6.4. 6.4 Adjust the liquid level in the burette to the zero mark by means of valve D (9). 6.5 Increase the pressure at the rate specified in 4.2 until the pressure gauge (3) shows the test pressure. Maintain this pressure in the test piece by closing valve B (5). Then determine the expansion immediately by opening valve C (7) and allowing the liquid in the expanded test piece to rise in the burette. As soon as the liquid level has become constant, close valve C (7) and record the volume in the burette. 6.6 Release the pressure and open valve B (5). Repeat the procedure as described in 6.5 twice, so that the final reading on the burette is the total volume of the three expansions.
Report the result in cubic centimetres per metre (cm 3 /m), rounded to the nearest 0,01 cm 3 /m. NOTE The result can be expressed as a percentage, if required, by determining the internal diameter and the free length of the hose assembly, and hence its volume, prior to testing. 8 Test report The test report shall include at least the following information: a) a reference to this document including its year of publication, i.e. ISO 6801:2021; b) a full description of the hose and its origin; c) the dimensions of the test piece; d) the test pressure; e) the correction factor for the apparatus; f) the total volume of the three expansions; g) the hose expansion, in cubic centimetres per metre (cm 3 /m), calculated according to Clause 7; h) the percentage volumetric expansion, if required; i) any deviations from the procedure; j) any unusual features observed; k) the date of the test.