[Comparative field study on high flow rate samplers for respirable fraction-A solution to smaller collected masses]

Dust sample mass gain is too smaller to satisfy the limit of detection (LOD) even in most cases during dust sampling at workplaces nowdays, especially for respirable fraction. Therefore, it is aimed to solve the problem by increasing sample load with high flow rate samplers.

In A and B two shipyards respirable welding fume was sampled by high flow rate cyclone samplers of FSP-10 (10 L/min) for 2-2.5 hours and normal flow rate FSP-2 (2 L/min) for 3-4 hours with a stratigy of parallele sampling at the same workpalce, in order to compare their mass gain, coincidence rate with LOD, and airborn dust concentration.

Sample mass gain of 0.97±0.40 mg and 1.61±0.86 mg respectively in the two factories by FSP-10 was significantly higher than that of 0.29±0.12 mg and 0.51±0.27 mg by FSP-2 (t-test, P<0.05 in both cases) , increasing herewith the coincidence rate with LOD from 26.8% (when sampling with FSP-2, calculated together with samples of the two factories) to 89.7%. However there was no significant difference in dust concentrations by the two different samplers, 0.53±1.88 vs 0.73±1.61 mg/m(3) by FSP-2 and FSP-10 in the shipyard A and 1.14±1.78 vs 1.01±1.63 mg/m(3) in the factory B (t-test, P>0.05 in every case) . In addtion, sample loading by FSP-2 was found to be correlated to sampling time (R(2)=0.7906, y=0.002 6x) , therefore, it has to sample for ≥192.3 min to meet the LOD (0.5 mg) in case of normal flow rate.

By using of high flow rate cyclone FSP-10 the problem of LOD could be solved, along with increased sample mass and similar respirable dust concentration by the two samplers. Some techincal improvements of FSP-10 and increasing of LOD coincidence rate by other methods was also disscussed.