How PPI Works
Only the patented* SKC Parallel Particle Impactor (PPI) Samplers contain four small impactors in the inlet section of the device. Each impactor features a unique 50% cut-point to target a specific one-quarter segment of the ISO/CEN curve resulting in a precise fit along the entire curve. A sample pump pulls air through the inlet nozzle of each impactor in the inlet plate. Particles larger than each impactor’s 50% cut-point are scrubbed and retained on the porous oiled impaction substrate, while smaller particles continue to the standard 37-mm collection filter for analysis.
* U.S. Patent No. 7,073,402
PPI Samplers Meet Requirements in OSHA Final Rule on Respirable Crystalline Silica
In its final silica rule, OSHA set a new permissible exposure limit (PEL) of 50 µg/m3 across all industries covered by the rule and abandoned the previous silica PEL formula. In addition, the OSHA final silica rule states that any sampler conforming to the ISO 7708/CEN criteria (50% cut-point of 4 µm) can be used for workplace silica and lists examples of samplers, including the impaction-based SKC PPI Samplers (final rule page 16439). The ISO 7708 criteria have been adopted by NIOSH, ACGIH, and many other global occupational hygiene organizations. Respirable PPI Sampler performance data, relative to the ISO 7708/CEN standard, was published in the Journal of Physics, Conference Series 151, 2009 and was made part of the OSHA Docket used to develop the OSHA final silica rule.
SKC PPI Performance
SKC PPI models were evaluated side by side with other size-selective samplers. Potassium sodium tartrate (PST), dioctyl phthalate (DP), glass spheres (GS), and coal mine dust were used as test aerosol. A load of approximately 6.8 mg of coal mine dust on the PPI substrates did not adversely affect PPI performance.
Collection efficiency of the 2, 4 and 8 L/min respirable PPI Samplers
compared to the ISO/CEN respirable curve
(Click to enlarge)
Comparison of penetration characteristics measured for the 2 and 8 L/min respirable
PPI Samplers and Higgins-Dewell Cyclone using PST test particles
(Click to enlarge)
Trakumas, S., Hall, P., Personal Respirable Sampler Containing Four Impactors Arranged in Parallel, Abstracts of 23rd Annual AAAR Conference, Atlanta, GA, 2004, p. 78
Trakumas, S., Salter, E., "Parallel Particle Impactor - Novel Size-selective Particle Sampler for Accurate Fractioning of Inhalable Particles," Journal of Physics: Conference Series 151 (2009), 16 pp., 012060
The link in the reference above is an author-created, non-copyrighted version of an article accepted for publication in the Journal of Physics: Conference Series 151. IOP Publishing Ltd. Is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. Go to http://dx.doi.org and enter doi: 10.1088/1742-6596/151/1/012060 for the definitive publisher authenticated version.
Trakumas, S., "High-flow Personal Respirable Dust Sampler for Increased Sensitivity," Poster 261, AIHce 2010, Denver, CO
Trakumas, S., "High-flow Personal Sampler to Monitor Exposure to Respirable Crystalline Silica at New Lower TLV, " IOHA 2010 8th Conference Book of Abstracts, Rome, p. 59
Trakumas, S., Salter, E., "High-Flow Personal Sampler to Monitor Exposure to Respirable Crystalline Silica at New Lower TLV." IOHA 2010, http://goo.gl/EzWm7m (PowerPoint Presentation)
ISO/CEN 7708:1995 (2008), Air Quality — Particle Size Fraction Definitions for Health-related Sampling, search on 7708
Stacey, P., Thorpe, A., and Echt, A., “Performance of High Flow Rate Personal Respirable Samplers When Challenged with Mineral Aerosols of Different Particle Size Distributions,” Ann. Occup. Hyg., 60, 2016, pp. 479-492, http://annhyg.oxfordjournals.org/content/60/4/479.full.pdf?etoc
OSHA Final Rule on Respirable Crystalline Silica, http://www.osha.gov/silica/
SKC Limited Warranty and Return Policy
SKC products are subject to the SKC Limited Warranty and Return Policy, which provides SKC’s sole liability and the buyer’s exclusive remedy. To view the complete SKC Limited Warranty and Return Policy, go to the SKC Limited Warranty for Products and Return Policy page.