BS EN ISO 7233:2016 pdf download – Rubber and plastics hoses and hose assemblies — Determination of resistance to vacuum (ISO 7233:2016)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 8330 apply.
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4 Principle
The test methodology for determining the resistance to vacuum of plastic and rubber hoses and hose assemblies consists of reducing the internal pressure in a length of hose by means of a vacuum pump and gauge, while examining the hose for any signs of deformation or delamination of reinforcement or lining.
5 Apparatus
5.1 Vacuum pump, provided with a gauge and capable of reducing the internal pressure in the hose within 60 s to the pressure specified in the product standard for the hose under test and maintaining it at that pressure for a minimum of 10 min.
5.2 Smooth, solid ball (for method A), with a diameter equal to 0,9 times the bore of the hose under test, rounded down to the nearest whole millimetre.
5.3 Two transparent airtight plates (for method B), for sealing each end of the hose. One of the plates shall permit attachment of the vacuum pump to the hose, while allowing internal visual inspection of the hose during the test.
6 Test pieces
If the complete hose or hose assembly is more than 1 m long, each test piece shall consist of a minimum length of hose, clear of the end fittings, of 1 m. If the complete hose or hose assembly is less than 1 m long, the complete length shall be used.
7 Conditioning of test pieces
No tests shall be carried out within 24 h of manufacture. Test pieces shall be conditioned at the appropriate temperature in accordance with ISO 23529 for at least 3 h before testing.
This 3 h period may form part of the minimum period of 24 h between manufacture and testing.
8 Test pressure
The internal pressure to which the hose is subjected to for the duration of the test shall be that stated in the product standard for the hose under test as being the minimum internal pressure which the hose is required to withstand.
9 Procedure (method A)
Lay out the hose as straight as possible on a flat surface and blank off one end to form an airtight seal.
Insert into the hose a smooth, solid ball (5.2) and then connect the open end of the hose to a vacuum pump and gauge. Reduce the pressure in the hose within 60 s to the required test pressure and maintain this pressure for the required period, which shall not be less than 10 min.
While the test pressure is being maintained, examine the hose externally for any signs of indentation or collapse and then tilt the hose to permit the solid ball to traverse the full length of the hose to check for any obstructions caused by internal deformation or delamination.
10 Procedure (method B) Lay out the hose as straight as possible on a flat surface and fit transparent airtight plates (5.3) to both ends of the hose, one of which shall then be connected to a vacuum pump and gauge. Reduce the pressure in the hose within 60 s to the required test pressure and maintain this pressure for the required period, which shall not be less than 10 min. While the test pressure is being maintained, examine the interior of the hose through one of the transparent plates by means of illumination supplied through the transparent plate at the other end of the hose for signs of delamination or blistering of the lining. Also examine the exterior of the hose for signs of indentation or collapse.