BS EN 482:2006 pdf download

BS EN 482:2006 pdf download.Workplace atmospheres—Genera lrequirements for the performance of procedures for the measurement of chemical agents.
3.15
standard uncertainty
uncertainty of the result of a measurement expressed as a standard deviation
(ENV 13005:1999)
3.16
uncertainty (of measurement)
parameter, associated with the result of a measurement, that characterizes the dispersion of the values that could reasonably be attributed to the measurand
IENV 13005:1999)
4 Classification
4.1 General
In this document measunng procedures are dassified according to measurement task. This classification is based upon the measurement strategy laid down in EN 689.
NOTE EN 689 deecnbes a number of measurement categones that involve a combinabon of these measurement tasks (see Annex A).
4.2 ScreenIng measurements of time weighted average concentration
Screening measurements of time weighted average concentration are performed to obtain relatively crude quantitative wiformation on exposure levels in order to decide if an exposure problem exists, and it so. to appraise its possible seriousness. These measurements can also determine if the exposure is well below or well above the (occupational exposure) limit value.
4.3 Screening measurements of variation of concentration in time andlor space
Screening measurements of variation of concentration in time andlor space are used to:
— provide information on the likely pattern of the concentration of chemical agents In air:
— identity locations and periods of elevated exposure;
— provide miormation on the location and intensity of emission sources:
estimate the effectiveness of ventilation or other technical measures
4.4 Measurements for comparison with (occupational exposure) limit values and periodic measurements
Measurements for comparison with (occupational exposure) limit values are used to obtain results of known precision and accuracy for the average concentration of a chemical agent ii the air in a workers breathing zone.
Periodic measurements are used to determine whether exposure conditions have changed since the measurements for comparison with limit values were performed, or whether control measures remain effective (see EN 689).
NOTE Since the composition of the workplace atmosphere will have been Investigated irlng the Initial occupational exposure assessment, it might be aproprIaie for periodic measurements to use procedures with lower selectivity
5 Performance requirements
NOTE Performance requirements for measuring procedures depend on the measurement task. The performance requirements for saeerg measurements are less stringent than for measurements for the conanson with timit values and periddic measurements. Therefore, the performance requirements tar screening measurements in 5.1 and 5.2 are only given in general tenns
5.1 Screening measurements of time weighted average concentration
The measurement procedures shall have:
adequate selectivity tot’ the chemical agent (see 42);
— averaging time less than or equal to the limit value reference Period;
— measuring range that pncludes the limit value;
expanded uncertainly that is fit far purpose (see 4.2).
5.2 Screening measurements of variation of concentration in time andior space
The measuring procedures shall have:
— adequate selectivity for the chemical agent (see 4.3):
short averaging time (for variation of concentration in time <5 mm; for variation or concentration in spaces 15mm); — measuring range that is fit for purpose (see 43); expanded uncertainly that is fit for purpose (see 4.3). 5.3 Measurements for comparison with limit values and periodic measurements 5.3,1 Unamblguity A measuring procedure shall produce an unambiguous result for the concentration of the chemical agent being measured in the specified measuring range, i,e an analytically determined value shall correspond to one concentration only. 5.3.2 Selectivity The measuring procedure shall contain appropriate information about the nature and magnitude of any interferences. NOTE Selectivity requirements vary from case to case, depending on what is known in advance about the workplace air. If the identity of al contaminents present not known ii afvance then the measuring procedure wil need to have a hi9h selectivity. If the identity of at canlamPiants is known prior to measurement, and there are no ir,terfwunts present, then it nght be possible to i.ae a measurement method with a low selectivity. Procedures for measuring chemical agents present as airborne particles shall prescribe a method for sampling the particle size fraction, as defined In EN 481, for wtiich the limit value for the chemical agent Is set. If different limit values are set for different species of a chemical agent. then the measuring procedure shall determine the individual species concerned.