BS EN ISO 7326:2016 pdf download – Rubber and plastics hoses – Assessment of ozone resistance under static conditions (ISO 7326:2016)
This document specifies five methods for determining the ozone resistance of the outer covers of hoses:
-method 1, for bore sizes up to and including 25 mm, carried out on the hose itself;
-method 2, for bore sizes greater than 25 mm, carried out on a test piece from the hose wall;
-method 3, for bore sizes greater than 25 mm, carried out on a test piece from the cover;
– method 4, for all bore sizes, carried out on the hose itself;
– method 5, for all bore sizes, carried out on hoses that are expandable, for example textilereinforced hoses.
NOTE For hoses with built-in fittings from which it is not possible to take test pieces, the ozone resistance can be assessed on slabs in accordance with ISO 1431-1, using test sheets of the appropriate polymeric compound vulcanized to the same degree.
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 1431-1:2012, Rubber, vulcanized or thermoplastic – Resistance to ozone cracking一Part 1: Static and dynamic strain testing
ISO 23529, Rubber – – General procedures for preparing and conditioning test pieces for physical test methods 3 Terms and definitions
For the purposes of this document, the terms and definitions given in IS0 8330 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
-IEC Electropedia: available at http://www.electropedia.org/
-IS0 Online browsing platform: available at ht://ww.isw.org/obep
4 General considerations
Method 1 and method 2 are the methods normally used, method 3 being used only if it is not possible to carry out the test in accordance with method 2. Method 4 is suitable for all bore sizes. Method 5 is specifically for testing expandable hoses in the expanded state.
The results of tests carried out in accordance with method 1 may not be comparable with the results obtained when tests are carried out in accordance with method 2 or method 3, even if the cover compounds of the hoses under test are identical in composition and are cured to the same degree. The test method to be used shall be as specified in the product standard.
All apparatus placed in the test cabinet shall be fabricated from materials which do not absorb or decompose ozone.
5.1 Ozone cabinet, with apparatus for generating ozone, monitoring and controlling the ozone concentration, as described in Iso 1431-1.
5.2 Test piece holder, as shown in Figure 1 (for method 1).
5.3 Test piece holder, as shown in Figure 2, made, for example, of wood coated with paint or aluminium (for method 2).
5.4 ig, for elongation of test pieces (for method 3).
Details given in ISO 1431-1:2012, 5.6 shall be fllowed.
5.5 Cylinder, as shown in Figure 3, with an outside diameter 2 times that of the specified minimum bend radius for the hose being tested or, if not specified, 8 times the outside diameter (for method 4).
5.6 Round rod, as shown in Figure 4, with an outside diameter 1,2 times the inside diameter of the hose being tested (for method 5).
6 Test pieces
6.1 Type of test piece
The test piece shall consist of a hose sample. The length shall be calculated by the fllowving formula:
L is the length of the test piece;
rb is the bend radius of the hose under test, as specified in 9.1.1;
dext is the outside diameter of the hose under test.
6.1.2 Method 2
The test piece shall consist of a strip cut longitudinally from the hose, The strip shall be 150 mm long and 25 mm wide.
6.1.3 Method 3
The test piece shall consist of a strip of the hose cover, 25 mm in width, removed longitudinally from the hose. Lightly buff the underside of the strip in accordance with IS0 23529 to remove any reinforcement impressions and thus ensure uniformity of strain along the length of the strip.BS EN ISO 7326 pdf download.