|The SKC Aluminum Cyclone is specified in NIOSH methods for silica and respirable dust. The Aluminum Cyclone is operated at 2.5 L/min to conform to the ISO/CEN 7708: 1995 criteria specified in the OSHA proposed silica rule.|
2.8 L/min for 3.5-µm cut-point
|Sample Pump||Universal XR or AirChek series|
Exploded View of Cyclone/filter Cassette Assembly
The SKC Aluminum Cyclone is a lightweight respirable dust sampler that is used with a filter loaded into a three-piece filter cassette. The cyclone separates dust particles according to size. The respirable particles collect on a filter for analysis while larger particles fall into the grit pot and are discarded.
The ACGIH, NIOSH, International Organization for Standardization, and European Standard Committee (ISO/CEN-ISO Standard 7708:1995) specify a collection efficiency curve with a median cut-point at 4 µm. When performing respirable dust sampling with cyclones, it is important to adjust the flow rate to give the closest possible match over the whole curve (not just at a single point). The ACGIH/ISO/CEN curve requires using the flow rate that minimizes the bias of the cyclone separation from this curve.
New York University Medical Center, a leading aerosol research organization, has calibrated the SKC Aluminum Cyclone and the results were carefully evaluated for bias over the whole curve, showing that 2.5 L/min* most closely matches the curve. The SKC Aluminum Cyclone meets the ACGIH/ISO/CEN curve at 2.5 L/min as specified in NIOSH Method 0600. The SKC Aluminum Cyclone is also specified in NIOSH 7500 for Silica and NIOSH 0600 for Particulates Not Otherwise Regulated.
The SKC Aluminum Cyclone is available in two sizes: 25 mm for use with 25-mm three-piece cassettes and 37 mm for use with 37-mm three-piece cassettes. The filter material, pore size, and support pad must be selected as specified by the sampling method used. A cyclone's collecting efficiency may be influenced by electrostatic effects. If the cyclone carries a net charge, particles of the same charge will be repelled by the cyclone and will not be sampled efficiently. SKC cyclones are constructed of conductive materials that eliminate the static problem associated with nylon (non-conductive) cyclones.
|*||As previously published, a 2.6-L/min flow rate will yield a 4-µm 50% cut-point, however, 2.5-L/min flow will provide a better match over the entire curve. Contact SKC Inc. for a copy of the calibration report on the SKC Aluminum Cyclone.|
|†||Determined using experimental data obtained at flows from 2 to 4 L/min|
The SKC Aluminum Cyclone is used with a three-piece filter cassette, a filter cassette holder, and a constant flow personal sampling pump such as one of the SKC Universal XR Series samplers.
A representative weighed filter with a support pad is placed into a three-piece cassette (with inlet section removed) and attached to the cyclone. The cyclone-cassette assembly is then attached to the filter cassette holder. The pump with the cyclone-cassette assembly in line is calibrated with a primary standard calibrator such as the Defender Calibrator Cat. No. 717 Series. The grit pot remains on the cyclone during calibration and sampling.
The cyclone is clipped to a worker’s collar or pocket as close to the breathing zone as possible. The pump is clipped to the worker’s belt or placed in a protective pouch. The pump is activated and the worker wears the apparatus during the entire sampling period. After sampling, the filter cassette is removed, sealed, and sent with all data to a laboratory for analysis.
Holder for 25 and 37-mm Cassettes
The lightweight filter cassette holder is designed to attach to a worker's collar and will accommodate either 25-mm cassettes with cowl or two or three-part 37-mm cassettes with or without a cyclone.
in filter cassette holder
Named for the rotation of air within its chamber, the cyclone is a particle size selector for sampling airborne particulates. It functions on the same principle as a centrifuge: the rapid circulation of air separates particles according to their equivalent aerodynamic diameter with the respirable particles collecting on the filter while the larger particles fall into the grit pot to be discarded. The cyclone/filter assembly is attached to a worker's collar near the breathing zone.
Respirable Dust and Sampling Efficiency Curves
Respirable dust refers to particles that settle deep within the lungs that are not ejected by exhaling, coughing, or expulsion by mucus. Since these particles are not collected with 100% efficiency by the lungs, respirable dust is defined in terms of sampling efficiency curves. These curves are sometimes referred to in terms of the 50% sampling efficiency or cut-point at a certain flow rate.
|A cyclone will not sample optimally if it is influenced by electrostatic charge. SKC cyclones are constructed of conductive plastic or aluminum that eliminates the static problem associated with nylon (non-conductive) cyclones.|
|Cleaning cyclones before sampling prevents deviation in the collection efficiency curves.|
Cyclones: A Centrifugal Force in Air Sampling PowerPoint Show
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