Document ID: chunk:federal_register_of_legislation:F2011C00880:body:0:p5
Version: federal_register_of_legislation:F2011C00880
Segment Type: other
Provision Reference: 
Character Range: 11172–13978

in conditions of darkness or near darkness. Inspection lamps must contain a filter to minimise the intensity of visible light and harmful ultraviolet light of wavelength less than 3,000A whilst permitting maximum transmission of ultraviolet light of wavelength approx. 3,650A.

      4.3 The intensity of ultraviolet light illumination at the surface to be inspected must be not less than 970 lumen m­² (735 Wcm­²) 90 foot candle when measured with a Weston Light Meter, Model 703, type 51 or equivalent or with an Ultraviolet Products Inc. Ultraviolet Meter, Model J-221 or equivalent.

      4.4 Before undertaking inspection in a darkened booth, a minimum period of 5 minutes must elapse after the inspector enters the booth to permit dark adaptation of his eyes.

5 Demagnetisation

      5.1 After final inspection and before final cleaning, all parts must be demagnetised.

      5.2 After demagnetisation, parts must be removed from the vicinity of the magnetising and demagnetising equipment to avoid remagnetisation.

      5.3 Ring shaped or very short components may require their effective magnetic shape to be changed by the use of extension pieces or shunts across their diameters, during demagnetisation, in order to achieve an acceptable degree of demagnetisation.
Appendix II

This Appendix specifies methods for computing magnetising current values for parts of essentially simple shape.

1 Circular magnetisation

      1.1 For circular magnetisation of round sections using current flow, the current used must be 30 amp. ac or 40 amp. dc per mm diameter. For non-circular sections, the current used must be 10 amp. ac or 13 amp. dc per mm of perimeter of the cross‑section.

      1.2 For circular magnetisation using the threading bar method, the current must be computed as in para. 1.1 above with respect to the outside diameter or periphery of the part.

2 Longitudinal magnetisation

       For longitudinal magnetisation using the coil method, when the part to be inspected is positioned adjacent to the inside surface of the coil, the current used must be computed from:

       A = ;

       and when the part to be inspected is positioned in the centre of the coil from:

       A = ;

       where A = current in amperes, dc or ac

        L = length of part

                 D = diameter or major cross-sectional dimension of the part (measured in the same units as L above)

        T = number of turns in the coil

        R = radius of coil in mm.

       These formulae are based on experiment and apply when the following conditions are met:

(a) the cross-sectional area of the part is not greater than one tenth of that of the coil;

(b) the part of the section or part to be inspected at the time is not more than 0.5 m long;

(c) the relative permeability of the