Dust-Measurement - Paul Gothe GmbH

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Isokinetic rate If the mean actual isokinetic rate during the sampling at the sampling plane differs for more than –5 % to +15 %, the measurement is not valid. If this criterion is not fulfilled due to frequent variation of the flow rate in the duct, see 10.2. 10.5 Deposits of dust on non-weighed parts upstream the filter Experimental work carried out when preparing this Standard proved that dust deposits upstream of the filter are often in the range of 10 % to 30 % of the total dust when sampling gases from waste incinerators at concentration around 5 mg/m 3 . These deposits depend probably on the design of the sampling equipment, and on the kind of dust to be sampled, but no efficient means was found to keep them at a negligible level. For this reason all non weighed parts of the sampling equipment prior to the filter shall be rinsed. The mass of dust on non-weighed parts upstream of the filter shall be indicated in the test report, besides the mass on the filters used during the same measurement series. When sampling with in-stack filtration devices with no bends between the nozzle and filter holder on non saturated gases, with a temperature well above the stack gas dew point, the upstream deposits do not have to be quantified provided that validation has been carried out at similar conditions as the process to prove that the deposits, expressed in the same units as the measurement results (e.g. in milligrams per cubic metre) do not exceed 10 % of the daily average limit value set for the process. Calculation See our formula sheet or ask for our excel file. 14
10. Determination of flow direction with Pitot tubes Type Prandtl-Pitot tube The type Prandtl Pitot tube provides an accurate measure of gas velocity when the Pitot tube is aligned (yawed) within 15° of the direction of the gas flow. However, the pressure difference between the two pressure-sensing orifices decreases sharply when misalignment exceeds 15°, until a negative response occurs when the head is at 90° to the gas flow. This provides a simple method for estimating gas flow direction and may be used to test for the presence of swirling flow within the duct. Type S Pitot tube The type S Pitot tube accurately measures the gas velocity to within 4 % when the Pitot tube is aligned (yawed) within 15° of the direction of the gas flow. However, when the planes of the Pitot tube pressure-sensing orifices are parallel to the stack flow, a null (zero) reading is obtained. Thus, the direction of swirling flow can be determined by rotating the type S Pitot tube (with the manometer properly zeroed and levelled) until a null reading is obtained. The direction of flow shall be parallel to the pressure-sensing orifice planes. 15
Page 1 and 2: Dust-Measurement Stationary source
Page 3 and 4: 4 Sampling points The sampling plan
Page 5 and 6: Alternatively, other measurement de
Page 7 and 8: Key 1 Entry nozzle 7 Dynamic pressu
Page 9 and 10: evaporation when heating; c) glass
Page 11 and 12: The solutions are transferred caref
Page 13: No mechanical cleaning shall be app
Page 17 and 18: Table C.1 gives values of Ki as a p
Page 19 and 20: i Table C.2 — Values of Ki as a p

Dust-Measurement - Paul Gothe GmbH

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