RSSV 4 2013.indd - Stazione Sperimentale del Vetro

4-2013
nota tecnica
Rivista della Stazione Sperimentale del Vetro
The choice is mainly linked to the detection limit required, which is linked to the limit values applied.
SSV suggests to apply a methodology able to guarantee at least a detection limit value of an order of
magnitude lower than the limit value (DL = Limit Value/10). The detection limit applied by SSV in Italy
is 0,0025 mg/m 3 (0,025/10).
To guarantee the very low detection limit value, SSV
is using the AFNOR X43 method which foresees the
use of a CIP 10 sampling device composed by a portable
pump with a fl ow rate of 10 l/min, a substrate dust
collection in polyurethane foam and a cyclone system
compliant with the European Standard EN 481 (respirable
fraction).
The methodology can be summarized as follows:
Chapter 4 of AFNOR X43:
Principle of the method
The aerosol particles present in the air to be analyzed are drawn into a rotating cup device fi tted with
polyurethane foam of a specifi ed grade, as described in NF X 43-262. For each particulate size, the
collection effi ciency of the device is approximately proportional to the corresponding probability of
the respirable alveolar deposit in a healthy person breathing in average ventilatory conditions. After
the foam has been carefully washed and dried, it is installed and weighed in the cup. It is weighed
again after sampling. The particles trapped by the foam are then recovered quantitatively by calcination
and collected on a fi lter. After a qualitative analysis of the fi lter by X-ray diffractometry to
determine the presence of crystalline silica and that of any interferents, the crystalline silica content
is determined on the most intense and non-interfered diffraction line. Calibration is performed using
fi lters loaded with a known mass of reference crystalline silica.
Based on the SSV experiences this is the only method able to guarantee very low detection limit inside
8 hour of sampling time.
SSV approach
SSV suggests the following approach for the silica crystalline monitoring:
• Number of personal sampling for each job fuction: 6
• Frequency of sampling: at least every two years
• Sampling and analytical method: AFNOR X43-295 “X-ray determination of the concentration
of crystalline silica respirable alveolar deposit - Sampling by means of a rotating cup device”
methodology to sampled and analyzed silica crystalline.
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