BS EN 170:2002 pdf download – Personal eye-protection — Ultraviolet filters — Transmittance requirements and recommended use
This European Standard specifies the scale numbers and transmittance requirements for filters for protection against ultraviolet radiation.
The other applicable requirements for these types of filters and the frames/mountings to which they are intended to be fitted are given in EN 1 66.
Guidance on the selection and use of these filters are given in annex B.
NOTE The protective filters specified in this standard are not suitable for the direct viewing of bright light sources like Xenon high-pressure arc lamps or for the direct or indirect observation of an electric welding arc. For this purpose a welding filter as specified in EN 1 69 and with a scale number appropriate to the source being observed should by used.
2 Normative references
This European Standard incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies (including amendments).
EN 1 65:1 995, Personal eye-protection – Vocabulary .
EN 1 66, Personal eye-protection – Specifications .
EN 1 67, Personal eye-protection – Optical test methods .
ISO/CIE 1 0526:1 999, CIE Standard illuminants for colorimetry .
ISO/CIE 1 0527:1 991 , CIE Standard colorimetric observers .
3 Terms and definitions
For the purposes of this European Standard, the terms and definitions given in EN 1 65:1 995 apply.
4 Designation and identification
The complete table of numbering of filters is given in EN 1 66.
The marking of oculars and frame is described in EN 1 66.
The scale number of ultraviolet filters comprises the code number 2 and the shade number corresponding to the filter, from 1 ,2 to 5 (see Table 1 ).
The requirements of EN 1 66 apply to ultraviolet filters. Only those requirements that are different from or supplement the EN 1 66 pecifications are given in this European standard.
5.2 Transmittance requirements
The definitions of transmittances are given in EN 1 65.
Minimum and maximum values of luminous transmittance may be exceeded by taking into account the limits of relative uncertainty given in EN 1 67.
a) for 21 0 nm ≤ λ ≤ 31 3 nm the spectral transmittance shall not exceed the value specified for 31 3 nm;
b) for 31 3 nm < λ ≤ 365 nm the spectral transmittance shall not exceed the value specified for 365 nm; c) for 365 nm < λ ≤ 405 nm the spectral transmittance shall not exceed the luminous transmittance; NOTE Luminous transmittance values are based on the spectral distribution of CIE illuminant A and on the CIE (1 931) standard observer (2°) (see ISO/CIE 1 0526:1 999 and ISO/CIE 1 0527:1 991 ). 5.3 Ocular with enhanced colour recognition (optional) Between 500 nm and 650 nm the spectral transmittance shall be not less than 0,2 τ v . The relative visual attenuation quotient Q , for signal lights red, yellow, green and blue shall be not less than 0,8.