BS EN 12254:2010 pdf download
BS EN 12254:2010 pdf download.Screens for laser working places——Safety requirements and testing.
7 Information supplied by the manufacturer
National legislation can define minimum requirements for information. At least the following information shall be supplied by the manufacturer or supplier in the national language(s) of the country to which the screen is sold:
a) Name and address of the manufacturer or supplier;
b) An explanation of the marking:
C) Description of the method of mountrng arid fixing of the screen;
d) Maintenance requirements, including e.g. details of inspection: details regarding appropriate cleaning, e.g. cleaning solutions, desinfectants and procedures which may be used:
e) A note that damaged screens should not be used:
1) In the case of screens with reflecting surfaces, or mirror layers a note that dust or splashes on the screen surface can reduce the resistance against laser radiation of the screen:
g) A note that in cases where the working process is to be observed, dazzling light may occur at the laser working place caused by high luminance, especially during laser welding. This note should include the recommendation to use a welding filter with appropriate scale number according to EN 169 in addition to transparent screens to avoid glare;
h) The laser parameters for which the resistance to laser radiation of the screen was tested;
i) A note that before selecting an appropriate screen, a risk assessment to determine the maximum reasonably foreseeable exposure should be performed see e.g. Annex B of EN 60825-4:2006);
j) A note that this assessment should be based on the powerienergy density averaged over a circular area not more than 1,13mm diameter;
k) A note that the recommendations for the use of screens at laser working places are based on the assumption of regular inspection the period of which is dependent on a risk assessment.
B.1 General
Before selecting an appropriate screen, a risk assessment to determine the maximum reasonably foreseeable exposure should be performed (see e.g. Annex B of EN 60825-4:2006).
This assessment should be based on the power.energy density averaged over a circular area of not more than 1,13mm diameter (1 mmd).
If this beam diameter or other beam diameters d than 1 mm (diameter to test resistance to laser radiation) are used to determine the scale number of an appropriate screen, power and energy densities of Table B.1 should be multiplied by the tollowing functions (dis the beam diameter in mm) depending on the main Constituent of the screen:
— Glass
— Plastic
NOTE Due to heal disslpabon, the to laser rac8ahon depends not only on the power and energy density, but also on the diameter 01 the irrac8aled area
The following recommendations for the use of screens at laser working places are based on the assumption of regular inspection the period of which Is dependent on a risk assessment.
The selection of screens is indicated in Table B. 1, the significance of the symbols D, I, R and U is given in Table 8.2.
B.2 Pulsed lasers
For pulsed lasers emitting at wavelengths equal to or greater than 400 nm, the total number N of the pulses within lOOs should be determined.
After calculating the energy densily H of the widivldual pulse II should be multiplied by W (H — H x A?). Thus with the resulting value Hthe required scale number can be read from Table Bi.
For pulsed lasers emitting at wavelengths below 400 nm. the single pulse energy density should be used for the selection of the screen.
These rules are based on EN 60825-1:2007.
In addition, the average power should be calculated for aM pulse sequences and compared with the values of the corresponding column marked D In Table Bi. It this results en a higher scale number, the higher one shall be used, or at least a screen should be used with individually specified scale numbers for pulsed mode (I, R or U) and continuous wave mode D.
