High-Efficiency Particulate Air Filter System Research Articles

The effect of a mobile HEPA filter system on ‘infectious’ aerosols, sound and air velocity in the SenseLab

High efficiency air filtration has been suggested to reduce airborne transmission of ‘infectious’ aerosols. In this study the ‘air cleaning’ effect as well as the effect on sound and air velocity (draught risk) of a mobile High-Efficiency Particulate Air (HEPA) filter system was tested for different settings and positions in the Experience room of the SenseLab. From both the noise assessments by a panel of subjects and sound monitoring it was concluded that the mobile HEPA filter system causes an unacceptable background sound level in the tested classroom setting (Experience room). With respect to the air velocity measurements and draught rating calculations, it was concluded that both depend on the position and the setting of the HEPA filter system as well as on the position and height of the measurements. For the removal of aerosols simulated by air-filled soap bubbles in front of the subject, the mobile HEPA filter system performed better as compared to the ‘No ventilation’ regime, for all settings and both positions, and for some settings, even better than all the tested mixing ventilation regimes. The use of a mobile HEPA filter system seems a good additional measure when only natural ventilation options are available. Future research should focus on rooms of different sizes or shapes, as this may also play a role in the filter's performance, noise and draught effects.

Home PAP devices in patients infected with COVID-19.

Citation:Kryger MH, Thomas R. Home PAP devices in patients infected with COVID-19. J Clin Sleep Med. 2020;16(7):1217–1219.

Operative and Technical Modifications to the Coriolis® µ Air Sampler That Improve Sample Recovery and Biosafety During Microbiological Air Sampling.

Detecting infectious aerosols is central for gauging and countering airborne threats. In this regard, the Coriolis® µ cyclonic air sampler is a practical, commercial collector that can be used with various analysis methods to monitor pathogens in air. However, information on how to operate this unit under optimal sampling and biosafety conditions is limited. We investigated Coriolis performance in aerosol dispersal experiments with polystyrene microspheres and Bacillus globigii spores. We report inconsistent sample recovery from the collector cone due to loss of material when sampling continuously for more than 30 min. Introducing a new collector cone every 10 min improved this shortcoming. Moreover, we found that several surfaces on the device become contaminated during sampling. Adapting a high efficiency particulate air-filter system to the Coriolis prevented contamination without altering collection efficiency or tactical deployment. A Coriolis modified with these operative and technical improvements was used to collect aerosols carrying microspheres released inside a Biosafety Level-3 laboratory during simulations of microbiological spills and aerosol dispersals. In summary, we provide operative and technical solutions to the Coriolis that optimize microbiological air sampling and improve biosafety.

Direct Determination of Ultra-trace Plutonium Nanoparticles in Downstream of a Six-Stage HEPA Filter by Inductively-Coupled-Plasma Mass Spectrometry: A Field Application

In this work, plutonium aerosol generated from a plutonium reprocessing facility is filtered by a six-stage High Efficiency Particulate Air (HEPA) filter system and analyzed in laboratory within a week. Through on-line monitoring of number concentration of particles above 10 nm by a commercial condensation particle counter and off-line monitoring of 239Pu activity concentration by 242Pu isotope dilution Inductively-Coupled Plasma Mass Spectrometry (ICP-MS), it is confirmed that the HEPA filter system works properly during the field operation. Direct determination of plutonium aerosol by two types of ICP-MS, Finnigan ELEMENT ICP-MS and Nu MC-ICP-MS, has been conducted. The results show that the detection limits of ELEMENT and Nu for plutonium concentration are 5.0 × 10−3 Bq/m3 and 5.5 × 10−4 Bq/m3, respectively. Plutonium concentrations in the filtered gas samples are on the order of 2.0 × 10−2 Bq/m3 while the blank value is 5.7 × 10−3 Bq/m3. It's discovered that some plutonium nanoparticles have penetrate...

In-Place Filter Testing Geometry Effects on Test Result Uncertainty: Single Stage Systems

In-place filter testing is a widely accepted practice for assuring performance of high-efficiency particulate air (HEPA) filter systems. American Society of Mechanical Engineers (ASME) standards address aspects of uncertainty in in-place filter test results through limits on spatial variation of test aerosol concentration and flow velocity. This article augments the standards by developing an approximate expression for test result uncertainty. The expression uses concentration, flow velocity, and penetration heterogeneities as indices of spatial variation. The uncertainty expression is used to evaluate testing of a hypothetical HEPA filter system meeting requirements of the standards and of an operating field HEPA filter system. At a performance acceptance limit of 5×10−4 penetration, uncertainty in tests on the standard system is just over the inferred ASME system acceptance limit of 6.7%. Uncertainty for field system tests is more than twice the limit. The uncertainty expression is used to determine lim...

Performance of High Efficiency Particulate Air Filters

To examine the performance of the high efficiency particulate air (HEPA) filter, demonstration tests were done in various conditions, such as; normal condition, high temperature and earthquake condition, using conventional deep-pleat filters, 610- × 610- × 292-mm in size. The authors found that the HEPA filter acted efficiently enough in various conditions supposed in the air purification system of a nuclear plant. Some empirical formulae were proposed to express the performance of the filter. The test results were summarized from these three points: (1) decontamination factor (DF) of intact filters, (2) mechanical strength and (3) pinholes, because these three points are important criteria in evaluating the performance of HEPA filter systems.

Performance of high efficiency particulate air filters.

To examine the performance of the high efficiency particulate air (HEPA) filter, demonstration tests were done in various conditions, such as; normal condition, high temperature and earthquake condition, using conventional deep-pleat filters, 610- × 610- × 292-mm in size. The authors found that the HEPA filter acted efficiently enough in various conditions supposed in the air purification system of a nuclear plant. Some empirical formulae were proposed to express the performance of the filter. The test results were summarized from these three points: (1) decontamination factor (DF) of intact filters, (2) mechanical strength and (3) pinholes, because these three points are important criteria in evaluating the performance of HEPA filter systems.

A new method for in-place testing of tandem HEPA filter installations.

A new in-place high-efficiency particulate air (HEPA) filter testing procedure has been developed, based on the use of an intracavity laser particle spectrometer for ultrasensitive detection of challenge particulate concentrations downstream of tandem HEPA filter installations. The feasibility of these measurements had initially been demonstrated on a small-scale laboratory system where overall protection factors of 10(9) were routinely measured. The primary scaling problem for systems up to 20 000 CFM was in producing sufficient challenge aerosol. This was accomplished by the design and construction of a high-volume thermal dioctyl phthalate generator. The results of acceptance testing of 13 tandem HEPA filter systems, performed with both the spectrometer technique and conventional light-scattering photometry, are displayed and problem areas discussed.