Evaluation of different discharging methods on HVAC electret filter media

Tang, Min; Thompson, D. P.; Chen, Sheng-Chieh; Liang, Yun; Pui, David Y.H.

doi:10.1016/j.buildenv.2018.05.048

Cited by 35 publications

(27 citation statements)

References 32 publications

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“…However, Kim et al observed no significant morphological change or swelling of the polymer fibers after exposure to liquid IPA . Tang et al (2018) assumed that saturated IPA vapor condensates on the fiber surfaces and calculated the thickness of the liquid IPA layer to a few nanometers via mass difference of the consumed IPA . Besides that, studies showed that unsaturated vapors of organic solvents do not lead to any discharge of the fibrous material …”

Section: Methodsmentioning

confidence: 99%

“…To conduct this discharging process, all but one of the participants used the commercially avail- 25 Tang et al (2018) assumed that saturated IPA vapor condensates on the fiber surfaces and calculated the thickness of the liquid IPA layer to a few nanometers via mass difference of the consumed IPA. 21 Besides that, studies showed that unsaturated vapors of organic solvents do not lead to any discharge of the fibrous material. 21,26 To explain and understand the discharging mechanisms of electret fibers in detail, experimental evidence and further research are needed.…”

Section: Dischargingmentioning

confidence: 99%

“…21 Besides that, studies showed that unsaturated vapors of organic solvents do not lead to any discharge of the fibrous material. 21,26 To explain and understand the discharging mechanisms of electret fibers in detail, experimental evidence and further research are needed.…”

Section: Dischargingmentioning

confidence: 99%

“…The previous method in Europe was the immersion of filter media into liquid IPA (EN 779) . One reason for change was the observation that efficiencies of electret filter media treated with saturated IPA vapor resulted in significant lower efficiencies compared to those which were treated with liquid IPA . Another reason was the demand for testing fully assembled filters instead of filter media, that is, the final product, which is used in the HVAC system.…”

Section: Introductionmentioning

confidence: 99%

“…19 One reason for change was the observation that efficiencies of electret filter media treated with saturated IPA vapor resulted in significant lower efficiencies compared to those which were treated with liquid IPA. [20][21][22] Another reason was the demand for testing fully assembled filters instead of filter media, that is, the final product, which is used in the HVAC system. Further changes are the usage of di(2-ethylhexyl) sebacate (DEHS, 0.3-1.0 µm) and potassium chloride (KCl, 1.0-10.0 µm) aerosols to measure the filtration efficiencies and the elimination of a compulsory dust-loading test (except for filters with ePM 10 values below 50% in which case a gravimetric efficiency has to be determined).…”

mentioning

confidence: 99%

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Air filters for indoor environments: Interlaboratory evaluation of the new international filter testing standard ISO 16890

et al. 2020

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Electret filters are widely used in HVAC systems to decrease particulate matter in indoor environments. The previous standard in Europe for testing air filters for general ventilation was EN 779. In July 2018, it was replaced by the new international standard ISO 16890. One major change is the discharging process: It is now performed by treating the filters with saturated isopropyl alcohol (IPA) vapor. The process is intended to simulate a worst‐case scenario of the filtration efficiency due to the reduction of the electret effect. These minimal efficiencies are a principal part of the filter classification. Therefore, two round robin tests with different filter classes (F9 and F7 according to EN 779) and up to eleven participants were carried out to evaluate the new test method by comparing the filtration efficiencies and pressure drops before and after the IPA treatment. Pressure drop measurements showed no mechanical altering of the material due to the discharging process. The calculated filter classes had a maximum deviation of 5%. Even with different equipment, the results indicate that the new ISO 16890 seems to be a viable test standard and a decent replacement for previous national standards.

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Section: Methodsmentioning

confidence: 99%

Section: Dischargingmentioning

confidence: 99%

Section: Dischargingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Air filters for indoor environments: Interlaboratory evaluation of the new international filter testing standard ISO 16890

et al. 2020

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Charge Protection in Electret Air Filtration Nonwoven Materials

Lavoie,

Rojas,

Khan

et al. 2024

Adv Materials Technologies

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Nonwoven media used as electret air filters are often embedded with charges to improve particle capture efficiency. These charged filters are invariably exposed to low surface tension fluids such as oils and alcohols leading to charge loss. In this study, filtration media are endowed with charge protection through increased surface repellency using melt additives that can migrate to the surface during processing. Nonwovens containing fluorochemical melt additives are produced, and examined to determine the relationship between surface chemistry, isopropyl alcohol (IPA) repellency, resultant charge retention, and filtration characteristics. Surface fluorine/carbon (F/C) ratios of ≈0.2 are sufficient to protect filtration performance from vapor discharging methods. Samples with bulk additive loadings of 1.2% or higher are found to achieve the necessary repellency to resist discharging independent of the migration state of the sample, while samples loaded at the 0.6% level required sufficient migration to achieve the requisite F/C ratio of 0.2 in order to be protected. Samples that achieved the necessary surface chemistry to provide significant IPA repellency retained > 80% of electret charge and corresponding filtration performance. These results have special significance in the design of filtration media relevant in global healthcare and other industrial settings.

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Filtration Performance Degradation of In‐Use Masks by Vapors from Alcohol‐Based Hand Sanitizers and the Mitigation Solutions

Guo

Liu

et al. 2021

Global Challenges

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In the current COVID‐19 pandemic, wearing masks and hand disinfection are widely adopted hygiene practices. Alcohol‐based sanitizers are commonly used for hand disinfection, however, the alcohol vapors can dissipate the charges on electrostatic filters. In the present study, the effects of alcohol vapors from alcohol‐based sanitizers during hand disinfection on the in‐use masks are studied. The results show that the negative effects are not significant for nonelectrostatic cotton masks or N95 respirators with multiple charged layers, but noticeable for surgical masks. After five rounds of hand disinfection, the filtration efficiencies of the filtering materials of the surgical masks decrease by more than 8% for 400 and 500 nm particles and by 3.7 ± 1.8% for 1 µm particles, the effective filtration efficiency of the surgical masks worn by the volunteers (with leakage considered) decreases by about 5% for ambient aerosol. In another process to imitate intensive disinfection procedures by healthcare workers, a 30 min surface cleaning process using alcohol‐based sanitizer is performed, and the effective efficiency of the N95 respirators worn by the volunteers decreases by nearly 9%. The simple practice of avoiding vapor during hand disinfection could mitigate the effects of alcohol vapor, which is demonstrated on two brands of surgical masks.

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Evaluation of different discharging methods on HVAC electret filter media

Cited by 35 publications

References 32 publications

Air filters for indoor environments: Interlaboratory evaluation of the new international filter testing standard ISO 16890

Air filters for indoor environments: Interlaboratory evaluation of the new international filter testing standard ISO 16890

Charge Protection in Electret Air Filtration Nonwoven Materials

Filtration Performance Degradation of In‐Use Masks by Vapors from Alcohol‐Based Hand Sanitizers and the Mitigation Solutions

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