ISO 5948-1994 pdf download – Railway rolling stock material – Ultrasonic acceptance testing.
9 Setting of the sensitivity of the instrument 9.1 General The setting of the sensitivity of the instrument shall be carried out under the same conditions (see 7.2 and clause 8) as the tests themselves. In the case of discontinuity-detection tests, in each case the sensitivity shall be set so that, within the area to be scanned outside the “dead zone”(see note 2 to table 1), a reference reflector with a diameter specified as acceptance standard in clause 12 can, irrespective of its distance from the surface to be scanned, be detected positively. NOTE 3 Calibration blocks applied for establishing the DGS diagrams or for setting the sensitivity according to 9.2, 9.3 or 9.4 shall have an acoustic attenuation similar to that of the wheels or tyres to be tested. 9.2 Sensitivity setting for wheels or tyres 9.2.1 For wheels or tyres to be tested with the beam in an axial or radial direction and to be evaluated by the distance-gain-size (DGS) method, the sensi- tivity is set with the help of the DGS diagram and the backwall echo occurring when axially testing the tyre or the wheel rim.
9.2.2 For wheels and tyres to be evaluated by the comparison method, the sensitivity shall be set: a) when being tested with the beam in an axial di- rection, with the help of a calibration block of the type shown in figure 1 and an internal reference standard of the type shown in figure2 (see note 4) (both may be combined in the same block); or b) when being tested with the beam in a radial di- rection, with the help of a calibration block of the type shown in figure3. NOTE 4 In this International Standard, “internal reference standard” means a calibration block with a bore on the backwall with the position, form, depth and diameter indi- cated in figure2. 9.3 Sensitivity setting for axles 9.3.1 For axles to be tested with the beam in a radial direction and to be evaluated by the DGS method, the sensitivity is set with the help of the DGS diagram and the occurring backwall echo.