Pinpricked external layer:
Over longer periods of use, gas particles start to penetrate a hose wall causing blisters or bubbles. Pinpricks – small holes in the outer layer of the hose prevent this process. It is particularly recommended for high pressure gases and hose sections near the fittings. Pinpricking can be performed in the factory or when hose assemblies are produced.
Static electricity:
For some applications, it is important to dissipate electrical charges from a hose (e.g. hoses for paint, organic solvents or when there is high fluid flow velocity). In this case, a hose with a metal braid or an additional conductor (for example, conductive fibres in a braid) must be used, and the fittings must be carefully assembled to maintain the electrical continuity of the hose.
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hose with a metal braid | hose with conductive fibres in a braid | hose with a conductive inner layer |
Assembly:
Thermoplastic hoses are assembled with Z-type high pressure hose fittings, which are crimped using crimping machines. In some cases M-type crimped fittings or S-type reusable fittings can be used. For ultra high pressure hoses (700 or 800 bar) P-type fittings are used (see HIGH PRESSURE HYDRAULICS – UHP thermoplastic hoses and fittings).