AS ISO 9934.3:2020 Non-destructive testing一Magnetic particle testing Part 3: Equipment.
8 Demagnetization
8.1 General
Facilities for demagnetization can be included in the magnetizing equipment, or demagnetizing can be carried out using a separate equipment.
If viewing for indications is carried out after demagnetization, indications shall be preserved by a suitable method.
8.2 Technical data
The following data shall be provided:
— method(s) of demagnetization;
— type of current regulation;
— field strength (at the centre of the empty demagnetizing coil if applicable);
— residual field for a specified component;
— electrical supply requirements at maximum current output (voltage, phases, frequency, and current) if separate from the general equipment;
— overall dimensions of equipment if separate from the general equipment;
— equipment mass, in kilograms, if separate from the general equipment.
8.3 Technical requirements
The equipment shall be capable of demagnetizing to a specified level (typically 0,4 kA/m to 1,0 kA/m) unless otherwise agreed.
9 Measurements
9.1 General
In connection with this part of ISO 9934, measurements are required for the following:
— determination of the equipment characteristics;
— checking inspection parameters.
For all current and magnetic field measurements, only instruments that respond directly to the waveform shall be used. Instruments that calculate peak or RMS values based on calculation derived from other values shall not be used. Where True RMS meters are used to measure RMS values the specified crest factor of the instrument shall be greater than the crest factor of the waveform being measured and generally not less than 5.
9.2 Current measurement
Pure AC sinusoidal waveforms can be accurately measured using clamp meters or other conventional instruments. Measurements of phase controlled currents can be more complex and it shall be verified that the instrument used has the correct response before use on these waveforms. Measurement systems using shunts with suitable voltage measurement instruments shall be regarded as current meters and conform with the requirements for such instruments.AS ISO 9934.3 pdf download.