BS EN ISO 3127:2017 pdf download

BS EN ISO 3127:2017 pdf download.Thermoplastics pipes – Determination of resistance to external blows – Round-the-clock method
1 Scope
This International Standard specifies a method for the determination of the resistance to extemal blows of thermoplastics pipes of circular Cross-section; it is called the round-the-clock method. This method is applicable to isolated batches of pipe tested at 0 “C (information is also given for sampling from the continuous production of Pipe). NOTE 1 If testing below 0 “C is required, a temperature of – 20 “C is recommended.
2 Definitions
For the purposes of this International Standard, the following definitions apply.
2.1 true impact rate (TIR): The total number of failures divided by the total number of blows, as a percentage, as if the whole batch had been tested. NOTE 2 In practice, test pieces are drawn at random from the batch and the result is only an estimate of the TIR for that batch.
2.2 failure: Unless otherwise specified in the product Standard, shattering or any Crack or Split on the Inside of the pipe that was caused by the impact and that tan be seen by the naked eye (lighting devices may be used to assist in examining the specimens). Indentation of the test piece is not considered a failure.
3 Principle
Test pieces are subjected to blows from a falling striker, of specified mass and shape, dropped from a known height onto specified positions around the circumference of the test piece. The true impact rate (TIR) of the batch, or production run from an extruder, is estimated. The severity of this test method tan be adjusted by changing the mass of the striker and/or by changing the drop height. lt is not technically correct to vary the severity of the test by choosing values of the TIR other than those specified below. The maximum value acceptable for the TIR is taken to belO%. NOTE 3 lt should be appreciated that a completely definitive result tan be reached only by testing the whole batch, but in practice a balance is necessary between the statistical possibility of a definitive result and the tost of further testing.
4 Apparatus
4.1 Falling-weight testing machine, incorporating the following basic components (see figure 1).
4.1.1 Main frame, with guide rails or a guiding tube rigidly fixed in the vertical Position, to accommodate a striker (4.12) and release it to fall vertically and freely. When calibrated, the Speed of the striker at the moment of impact shall be not less than 95 % of the theoretical Speed.
4.1.2 Striker, having a nose comprising all or part of a hemisphere, combined with a cylindrical stem at least 10 mm long, and having dimensions conforming to figure 2 and table 1, depending upon the mass of the striker. The mass of the striker, including any associated weights, shall be selected from the values given in table 2. Below the Stern, the nose shall be of steel with a minimum wall thickness of 5 mm and the striking surface shall be free from visible imperfec- tions such as scratches or dents which may influence the results.