The filters must be contained in an electrically conductive cassette assembly that includes a 50-mm extension cowl (see Figure F-5 in Appendix F). An electrically conductive cassette is necessary to prevent loss of fibers to the walls of the cassette due to electrostatic forces. Diffusive samplers begin to sample as soon as they are opened and continue to sample until they are sealed. Новая модель Irbis TTR 250 представляет собой достаточно жесткий эндурик (не в смысле характеристик подвесок, а по части заточенности на бездорожье). Аппарат предельно легкий, с «зубастыми» шинами размеров 21/18 дюймов и значительным клиренсом. Wear eye protection when breaking ends, and be careful not to cut yourself. Do not use the charging inlet or the exhaust outlet of the pump to break the ends of the tube.
The weight of the respirable dust in the air sample (expressed as mg or μg) is the net filter weight gain, as determined by the laboratory. Ensure that the sampler remains properly assembled and that the tubing does not become pinched or detached from the collection device or from the pump. Exposures to CO and nitrogen oxides are also associated with welding activities, although such exposures are not usually a concern in open shop welding. CO and NO2 sampling should be conducted when welding is performed in confined spaces. And based on the maximum sample volume and flow rate, determine the maximum duration per sampler. Figure 5. Large Protective Tube Cover for Sorbent Tubes in Series (Photo courtesy of NIOSH) Sampling tubes may also be used in parallel. However, this must be balanced against the need to replace the collection medium when overloading of the sampling medium is anticipated or observed during sampling.
Turn off the pump and document the stop time (time off). Remove the collection device from the connecting tubing and close both the inlet and the outlet of the collection device as appropriate, for example using caps or plugs. Never pressurize the flow cell with more than 25 inches of water pressure. Proper soap solution is available from the CTC’s expendable supplies program. Store in the case to protect from breakage or dust accumulation. After sampling, replace the face cover and end caps and secure the Form OSHA-21 seal, then post-calibrate the sampling pump.