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 %. 4.2.2 Electrodes and contacts 4.2.2.1 General For tests conducted in a laboratory, the equipment described below shall be used. For field tests, and for routine tests and product acceptance tests in a manufacturer’s plant, this equipment is not practical, and alternatives may be used as described in 4.6.1, 4.7.1.2 and 4.7.2.3. Electrodes shall be formed on the surface as bands 25 1 2 − + ( ) mm wide around the circumference by means of a conductive silver lacquer, colloidal graphite or a conductive liquid. When a conductive liquid is used, the electrode contact area shall be completely wetted and shall remain so until the end of the test. Unless otherwise specified, the conductive liquid shall consist of — 800 parts by mass of anhydrous poly(ethylene glycol) of relative molecular mass 600; — 200 parts by mass of water; — 1 part by mass of wetting agent; — 10 parts by mass of potassium chloride. When a conductive silver lacquer or colloidal graphite is used, the surface resistance between any two points on a sample of the dried film shall not exceed 100 Ω. Clean metal contacts shall be applied to the electrodes so that the contact area is approximately the same size as, but no greater than, the electrodes, except where otherwise stated. In the case of hoses of...
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