BS EN ISO 8031:2020 pdf download.Rubber and plastics hoses and hose assemblies — Determination of electrical resistance and conductivity.
4.2.1.2 For tests requiring the measurement of the electrical continuity between end fittings or through continuous internal or external bonded wires, the instrument used shall be an ohmmeter sufficiently accurate to determine the resistance to within ±10 %.
4.2.1.3 For tests where, according to the product standard, determination of the electrical continuity between the end fittings of a hose assembly is required, without measurement of the actual electrical resistance, a 4,5 V battery in combination with a 4 V (0,3 A) test lamp can be used.
4.2.1.4 For determination of the electrical resistance through the hose wall (required by some hose product standards for hoses used in explosive atmospheres), the instrument used shall be an ohmmeter with a capacity of 10 12 Ω and the measurement shall be made at 500 V d.c. The instrument shall be sufficiently accurate to determine the resistance between the lining and the cover as measured through the hose wall to within ±5 %.
4.9.2.1 Preparation for the test Prepare the test pieces by cutting five lengths of hose approximately 300 mm long from samples taken at random from a production run. Use an ohmmeter with a capacity of at least 10 10 Ω and make the measurement at 500 V d.c. The instrument shall be sufficiently accurate to determine the resistance between the lining and cover, measured through the hose wall, to within ±5 %.
4.9.2.2 Electrodes and contacts For the outer electrode, see 4.2.2.1. For hoses with corrugated covers, a wetted conducting foam strip underneath the electrode is recommended to ensure good contact over the entire electrode surface. For the use of conductive liquid or conductive silver lacquer or colloidal graphite, see 4.2.2.1. The inner electrode shall consist of tap water with an electrical conductivity of at least 10 −4 S/m.
4.9.2.3 Preparation and cleaning for test The surfaces of the test piece shall be clean. If necessary, they may be cleaned by rubbing with fuller's earth (magnesium aluminium silicate) and water, washing with distilled water and allowing to dry. Do not use organic materials which attack the material of the test piece or cause it to swell, and do not buff or abrade the test surfaces. The surface of the test piece shall not become deformed either during the application of the contacts or during the test. Care shall be taken to ensure that the test piece is insulated from any electrical leakage path along its length.
4.9.2.4 Conditioning See 4.4.BS EN ISO 8031 pdf download.