정전방식, 적층수 및 온․습도변화에 따른 마스크 여과재의 성능평가

Abstract

연구목적 유해인자로부터 근로자의 호흡기 건강을 보호하기 위해 방진마스크에 정전기 여과재를 사용한다. 본 연구에서는 현재 국내에서 가장 많이 사용되고 있는 2가지 정전여과재(하이드로 정전여과재, 코로나 정전여과재)에 대한 Nacl입자 및 Paraffin oil 에어로졸에 대한 차압과 포집효율 성능을 파악하고자 하였다.

연구방법 마스크 완제품이 아닌 여과재 원단(평량 30g/m2)을 이용하여 고체(Nacl)와 액체(Paraffin oil)에어로졸에 대해 120mg 부하시험(loading test)을 실시하였다. 이때 TSI사 AFT 8130을 이용하여 정전여과재의 차압과 포집효율을 측정하였다. 또한 표면 정전위와 포집효율과의 관계를 파악하기 위해 같은 측정기를 이용하여 필터테스트(Filter test)를 추가로 실시하였다.

연구결과 1. Nacl입자에 대해 하이드로 정전여과재의 평균 차압은 428.33Pa, 평균 포집효율은 99.98%, 코로나 정전여과재의 평균 차압은 396.54Pa, 평균 포집효율은 97.84%를 보였다. 두 여과재간에 평균 차압은 약 31.79Pa, 평균포집효율은 2.14%의 차이를 보였다. 차압은 코로나 여과재가 좋고 포집효율은 하이드로 여과재가 좋은 것으로 분석되었다. 통계검정 결과, α=0.05에서 차압(p=0.310)은 차이가 없고, 포집효율(p<0.001)은 두 여과재간에 차이가 있는 것으로 나타났다. 또한 Paraffin oil입자의 경우, 하이드로 정전여과재의 평균 차압은 60.23Pa, 평균 포집효율은 98.85%, 코로나 정전여과재의 평균 차압은 98.62Pa, 평균 포집효율은 81.18%를 나타냈다. 차압 및 포집효율 모두 하이드로 정전여과재가 좋은 것으로 분석되었다. 통계검정 결과 α=0.05에서 차압(p<0.014)과 포집효율(p<0.001)은 두 여과재 간에 각각 차이가 있는 것으로 나타났다. 2. 고온고습(70℃95%) 전처리한 하이드로 정전여과재의 경우, Nacl입자에 대한 평균 차압은 411.05Pa(표준상태 428.33pa), 평균 포집효율은 99.86%(표준상태 99.98%)를 나타냈다. 표준상태 여과재와 비교시 차압은 일부 감소 또는 증가하였지만 평균포집효율은 0.12% 정도 감소하였다. 그리고 통계검정 결과 α=0.05에서 표준상태 여과재와 차압(p=0.787)은 차이가 있다고 할 수 없고, 포집효율(p<0.046)은 차이가 있는 것으로 나타났다. 아울러 Paraffin oil 입자의 경우, 평균 차압은 58.55Pa(표준상태 60.23pa), 평균 포집효율은 96.61%(표준상태 98.85%)을 나타냈다. 표준상태와 비교시 평균 포집효율은 약 4%정도 감소하였고, 차압은 6.5Pa 감소하였다. 통계검정 결과 α=0.05에서 고 온고습 전처리한 여과재의 차압(p<0.010) 및 포집효율(p<0.001)은 표준상태 여과재와 차이가 있는 것으로 나타났다. 3. 고온저습(70℃20%) 전처리한 하이드로 정전여과재의 경우, Nacl입자에 대한 평균 차압은 428.65Pa(표준상태 428.33pa), 평균 포집효율은 99.97% (표준상태 99.98%)를 나타냈다. 표준상태와 비교시 차압과 포집효율 모두 거의 차이가 없었다. 통계검정 결과, α=0.05에서 Nacl입자에 대해서는 평균 차압(p=0.820) 및 평균 포집효율 (p=0.801)은 표준상태 여과재와 차이가 있다고 할 수 없는 것으로 나타났다. 그리고 Paraffin oil입자의 경우, 평균 차압은 54.96Pa(표준상태 60.23Pa), 평균 포집효율은 99.00%(표준상태 98.85%)로 나타났다. 표준상태와 비교시 차압과 포집효율 모두 거의 차이가 없었다. 에서 평균 차압(p<0.010)은 표준상태 여과재와 차이가 있고 평균 포집효율 (p=0.663)은 표준상태 여과재와 차이가 없는 것으로 나타났다. 4. 표면정전위와 포집효율과의 관계를 보면, Nacl입자에 대한 표면 정전위와 포집효율간의 상관계수는 0.152(p=0.424), Paraffin oil입자에 대해서는 상관계수가 0.454(p<0.012)로 서로 상관관계가 있는 것으로 나타났다. 또한 무(無)정전 여과재의 필터 테스트 결과, Nacl입자에 대해 약 34.22%, Paraffin oil입자에 대해 약 32.42%가량 정전기가 포집 효율 상승에 기여하는 것으로 파악되었다. 5. Nacl입자에 대해 하이드로 여과재 2겹의 평균 포집효율은 100%로 1겹일 때 99.98%보다 상승하였고, 코로나 여과재의 경우, 2겹일 때 평균 포집효율은 99.96%로 1겹일 때 97.84%보다 상승하였다. 아울러 Paraffin oil입자의 경우, 하이드로 여과재는 2겹일 때 평균포집효율은 99.99%로 1겹일 때 98.86%보다 상승하였다. 그리고 코로나 여과재의 경우 2겹일 때 평균포집효율은 95.79%로 1겹일 때 81.34%보다 상승하였다. 즉 적층수 증가는 정전방식에 관계없이 포집효율 상승에 기여하는 것으로 나타났다.

결론 1. Nacl입자의 경우, 포집효율은 하이드로 여과재가 코로나 여과재에 비해 좋은 것으로 나타났으나 차압은 코로나 여과재가 좋은 것으로 관찰되었다. Paraffin oil입자의 경우 하이드로 여과재가 차압과 포집효율 모두 좋은 것으로 관찰되었다. 2. 정전여과재의 포집효율은 고습도에 영향을 받는 것으로 관찰되었다. 또한 Nacl입자에 비해 Paraffin oil입자가 더 큰 영향을 받는 것으로 나타났다. 다만 차압은 포집효율 변화에 비하면 온도 및 습도에 크게 영향을 받지 않는 것으로 관찰 되었다. 3. 정전기와 포집효율은 Nacl입자와 Paraffin oil입자 모두에 상관관계가 있고 정전기는 섬유 구조와 더불어 포집효율 증가에 기여하는 것으로 관찰되었다. 4. 여과재의 층수 증가시, 고체 및 액체 입자 모두에 하이드로 여과재 포집효율이 코로나 여과재 보다 우수하였다. 아울러 코로나 정전여과재가 층수가 증가함에 따라 Paraffin oil 입자에 대해 포집효율 개선이 가장 큰 것으로 관찰되었다.

Introduction : To protect the respiratory health of workers from harmful particles, electrostatic filter media are used in dust mask. In this study, the pressure drop and filtration efficiency of two currently commonly used electrostatic fabrics in Korea, namely, the hydro- and corona-charged fabrics, for NaCl particles and paraffin oil aerosols were investigated.

Methods : A 120 mg loading test was performed on solid (Nacl) and liquid (Paraffin oil) aerosols using a filter material fabric (basis weight 30 g/m2) and not a mask. The pressure drop and filtration efficiency of the electrostatic filter fabrics were measured using TSI-8130 AFT. In addition, a filter test was performed using the same measuring device to determine the relationship between the surface potential and the filtration efficiency.

Results 1. For Nacl particles, the average pressure drop of the hydro- charged fabric was 428.33Pa and the average filtration efficiency was 99.98%, while the average pressure drop of the corona-charged fabric was 396.54Pa and the average filtration efficiency was 97.84%. The average pressure drop between the two fabrics was about 31.79Pa and the average filtration efficiency was approximately 2.14%. It was concluded that the corona-charged fabric was better in terms of pressure drop and the hydro-charged fabric was better in terms of the filtration efficiency. As a result of the statistical test, there was no difference in the pressure drop(p=0.310) and the filtration efficiency (p<0.001) between the two fabrics was found to be different. In addition, in the case of paraffin oil particles, the average pressure drop of the hydro-charged fabric was 60.23Pa and the average filtration efficiency was 98.85%, while the average pressure drop of the corona-charged fabric was 98.62Pa and the average filtration efficiency was 81.18%, In terms of pressure drop and filtration efficiency, the hydro-charged fabric was better than the corona-charged fabric. In the statistical test results, it was found that the pressure drop (p<0.014) and filtration efficiency (p<0.001) between the two fabrics were different. 2. In the case of the hydro-charged fabric preconditioned at high temperature (70℃) and high humidity(95%), the average pressure drop for NaCl particles was 411.05Pa (428.33Pa in the standard state) and the average filtration efficiency was 99.86% (99.98% in the standard state). Compared with the fabric in the standard state, in the case of pressure drop, some of the preconditioned samples increased and other decreased, but the average filtration efficiency decreased by 0.12%. The statistical test results at a confidence level of 95% showed that there was no difference in the pressure drop (p=0.787), but the filtration efficiency (p<0.046) differed. In addition, in the case of paraffin oil particles, the average pressure drop was 58.55Pa (60.23Pa in the standard state) and the average filtration efficiency was 96.61% (98.85% in the standard state). Compared with the fabrics in the standard state, the average filtration efficiency of preconditioned fabric decreased by approximately 4% and the pressure drop decreased by 6.5Pa. The statistical test results showed that the pressure drop (p<0.010) and filtration efficiency (p<0.001) of the fabric preconditioned at high temperature and high humidity were different from those in the standard state. 3. In the case of the hydro-charged fabric preconditioned at high temperature (70℃) and low humidity (20%), the average pressure drop for NaCl particles was 428.65Pa (428.33Pa in the standard state) and the average filtration efficiency was 99.97% (99.98% in the standard state). When compared with the fabric in the standard state, there was almost no difference in both the pressure drop and the filtration efficiency. As a result of the statistical test, it was found that the average pressure drop (p=0.820) and the average filtration efficiency (p=0.801) for NaCl particles was not different from that of the standard state fabric at a confidence level of 95%. In the case of paraffin oil particles, the average pressure drop was 54.96Pa (60.23Pa in the standard state) and the average filtration efficiency was 99.00% (98.85% in the standard state). When compared with the standard state, there was almost no difference in both the pressure drop and the filtration efficiency. The average pressure drop (p<0.010) of preconditioned fabric was different from that of fabric in the standard state and the average filtration efficiency (p=0.663) was not different from that of fabric in the standard state. 4. Regarding the relationship between the surface potential and the filtration efficiency, the correlation coefficient for NaCl particles was 0.152 (p=0.424) and 0.454 (p<0.012) for paraffin oil particles. In addition, as a result of the filter test of the non-electrostatic fabric, it was found that electrostatics contributed to an increase in filtration efficiency by approximately 34.22% for NaCl particles and 32.42% for paraffin oil particles. 5. For NaCl particles, the average filtration efficiency of 2 layers of hydro-charged fabric was 100%, which was higher than single layer fabric(99.98%). In addition, in the case of paraffin oil particles, the average filtration efficiency of the double-layer hydro-charged fabric was 99.99%, which was higher than single layer fabric (98.86%). In the case of double-layer corona-charged fabric, the average filtration efficiency was 95.79%, which was higher than single-layer fabric (81.34%). In other words, it was found that the increase in the number of layers contributed to the increase in filtration efficiency regardless of the method of charging.

Reviews 1. In the case of NaCl particles, it was observed that the hydro-charged fabric was better than the corona-charged fabric in the filtration efficiency, but the pressure drop was better for the corona-charged fabric. In the case of paraffin oil particles, it was observed that the hydro-charged fabric was better in terms of pressure drop and filtration efficiency. 2. It was observed that the filtration efficiency of the electrostatic fabric was affected by high humidity. In addition, it was found that paraffin oil particles affected the filtration efficiency more than NaCl particles. However, it was observed that the pressure drop was not significantly affected by temperature and humidity compared to filtration efficiency. 3. Electrostatics and filtration efficiency are correlated, and electrostatics contributes to the increasement in filtration efficiency. 4. When the number of layers of the fabric was increased, the filtration efficiency of the hydro-charged fabric against both solid and liquid particles was better than that of the corona-charged fabric. In addition, as the number of layers of the corona-charged fabric increased, it was observed that the filtration efficiency was greater for paraffin oil particles.