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標題: | 動力淨氣式呼吸防護具效能評估與研發 Performance Evaluation and Development of Powered Air-Purifying Respirators |
作者: | Chao-Hao Hsu 許釗豪 |
指導教授: | 陳志傑(Chih-Chieh Chen) |
關鍵字: | 動力淨氣式呼吸防護具,呼吸回饋,呼吸流量,緊密接合式,呼氣閥, Powered Air-Purifying Respirators,Breath-responsive,Breathing flow,Tight-fitting,Exhalation valve, |
出版年 : | 2020 |
學位: | 碩士 |
摘要: | 第一部分
動力淨氣式呼吸防護具(Powered air-purifying respirators, PAPRs)是以送風主機搭配濾罐,將空氣進行過濾,再供至面罩內呼吸。欲保持面罩內正壓,需搭配較大的送風主機以維持流量,然而,若面罩內可能因流量過大,使面罩內壓力過高,對於長時間佩戴造成呼吸上負擔,故本研究先評估市售呼吸回饋式PAPRs特性,並比較各類型PAPRs在各呼吸條件下面罩內壓力大小,並提出使用時機之建議。 本研究探討市售PAPRs之效能,主要方式是佩戴於假人模型,接上呼吸模擬器,調整不同潮氣容積及呼吸頻率以模擬不同工作負荷(7.5 – 105 L/min)。以壓差計監測面罩內壓力,而送風主機之供給流量則以風速計作量測。 比較呼吸回饋式與定流量式PAPRs在不同呼吸條件下面罩內壓力變化得知,一款緊密式呼吸回饋式PAPRs在大呼吸流量下可維持面罩內6 – 8 mmH₂O正壓,但在呼吸通量較小時,面罩壓力達30 mmH₂0,另一款則在呼吸流量50 L/min 以下可維持面罩內約 4 mmH₂O 正壓;寬鬆式定流量式PAPRs一般提供150 L/min以上,在極端劇烈呼吸條件時,才會有負壓的情形發生,而於呼吸通量較小(< 20L/min)則可維持較小正壓。以吐氣之最大之壓力值得知,緊密接合式PAPRs因送風量較大,對吐氣造成阻抗,佩戴較為不適。 緊密式呼吸回饋式PAPRs適用於重工作負荷條件下,然而在呼吸較平緩時,因供給之流量依舊過大,呼氣壓力偏高,使佩戴較為不適;若在一般呼吸條件下,考慮正壓防護及佩戴舒適性,則建議使用半面體呼吸回饋式PAPRs,而未來研究可朝降低吐氣壓力方向進行,可大幅改善舒適程度。 第二部分 市售兩款具呼吸回饋式呼吸防護具依體積可分為大(全面體+輸送管+送風主機)、小(尺寸僅為半面體)兩型,而各有其使用限制:大型因送風流量仍過大,因此呼吸較為平緩時,會造成面罩壓力過大之問題;小型雖以較小風扇並搭配回饋程式,可使吸氣壓力峰值降低,但使用之呼氣閥仍為傳統之單向閥,呼氣壓力峰值隨呼吸流量上升而增加,無法達面罩內最小壓力之目標。本研究選用一合適之風扇與自行設計之電動閥,並搭配程式設計,改善目前市售呼吸回饋送風呼吸防護具之限制,於吸氣與吐氣階段皆可維持一最小正壓。 本研究可分別市售防護具之改善與研發兩部分。第一部分為針對大風量式進行改善,方法為選用一市售離心扇,搭配程式撰寫,以取代原送風主機,並調整不同潮氣容積及呼吸頻率以模擬不同工作負荷(7.5 – 60 L/min),與大型PAPRs比較面罩內壓力峰值。第二部分則針對小風量式進行研發,方法為使用一自行設計之圓筒閥並透過伺服馬達進行轉動,送風主機則選用一小型風扇,同樣地透過程式撰寫,依據面罩內壓力變化進行閥轉動與風扇送風流量調整,並與市售小型PAPRs於不同呼吸條件下 (7.5, 15, 30 L/min)比較面罩內壓力值。 研究結果顯示,於大型PAPRs改善部分,運用自行設計呼吸回饋程式搭配市售之風扇,在呼吸流量為7.5 – 60 L/min下,吸氣壓力峰值可維持至0 – 2 mmH2O,吐氣壓力峰值也隨風量調整而有所下降。於研發部分,透過呼吸回饋程式之設計,使得風扇與電動閥分別於吸氣與吐氣階段互相連動,在呼吸流量為7.5 – 30 L/min下,吸氣與吐氣壓力峰值可維持至0 – 4 mmH2O。 透過合適之風扇與電動閥,以及呼吸回饋程式設計,針對每一呼吸運動即時反應,一方面改善因送風量遠大於吸氣量,而導致壓力過高之問題,另一方面也透過電動閥於呼氣階段開啟,使呼氣更為順暢,大幅減少因傳統單向閥所造成之氣體排出不易之情形,使得面罩內維持一最小正壓,提升佩戴之舒適度。 Part 1 Powered air-purifying respirators (PAPRs) are equipped with a battery powered blower to push atmospheric air through a filter into the respirator cavity. In order to maintain positive pressure inside respirator, the supply air flow must be higher than the breathing flow. However, if the supply flow into the mask is too large, the pressure inside the mask would become a respiratory burden. This study aimed to evaluate the performance characteristics of commercial PAPRs, and to make a comparison of different types PAPRs with pressure inside the facepieces in order to give some advice. Five type of PAPRs were evaluated in the study. The PAPRs was donned on a head-form connected to a breathing simulator, with adjustable tidal volume (0.5-3 L) and breathing frequency (15-35 time/min), to simulate different breathing conditions. Pressure transducers is used to monitor the pressure change inside respirator, and the flow rate generated by the blower was measurement by using a air velocity meter. The results showed that one set of breath-responsive PAPRs can maintain 6-8 mmH2O in extremely high breathing flow. However, for lower breathing flow, the static pressure inside respirator could be as high as 30 mmH₂O due to the high supply flow. The other set of breath-responsive PAPRs can maintain about 4 mmH2O when breathing flow is below 50 L/min. For constant flow PAPRs, the static pressure was less than the breath-responsive PAPRs, however, negative pressure occurred under extremely high breathing flow. From the maximum pressure of exhalation, donning on the tight-fitting facepiece and the high supply flow, it may cause the burden of exhalation. The breath-responsive PAPRs is apparently designed for heavy working conditions. With the excessive supply air flow, too high static pressure inside respirator is uncomfortable to the wearer. Therefore, considering the protection and level of comfort, the one PAPRs, with breathing response and half-mask, is more suitable to use. In addition, the study will continue the way of reduce the exhalation pressure. Part 2 The commercial Breath-Responsive Powered Air-Purifying Respirators (BR-PAPRs) can be divided into two parts, the big one (full-facepiece, air-supplied tube and blower) and the small one (only half-facepiece). However, there are some restrictions on the two BR-PAPRs : the excessive air flow supplied by the one with high flow rate, the static pressure inside respirator was too high in gentle breathing condition ; Although the one with low flow rate could maintain lower positive pressure than the one with high flow rate by a small blower and a real-time response microcontroller, the peak pressure of exhalation was too high by the increasing of the breathing flow with the one-way valve. This study aimed to choose fit blowers and design a new motor exhalation valve, and then connect with the microcontroller. So, the pressure inside respirator could maintain the lowest positive pressure of inhalation and exhalation. In the improvement section, the original blower with high flow rate was replaced by a commercial blower, connected to the microcontroller programmed by ourselves. Then, compared the peak pressure of inhalation and exhalation in different breathing flow (7.5 – 60 L/min) of the before and after improvement. In the development section, a cylinder exhalation valve was designed and rotated by a servo motor, and then a small axial fan was selected as blower unit. Similarly, all of the components were connected to the microcontroller programmed by ourselves. Finally, compared the peak pressure of inhalation and exhalation in different breathing flow (7.5, 15 and 30 L/min) of the new one and original one of low flow rate BR-PAPRs. The results of the improvement part showed that the peak pressure of the inhalation could be maintain between 0 – 2 mmH2O when the breathing flow is below 60 L/min. Moreover, the peak pressure of the exhalation was also lower than the original one of high flow rate BR-PAPRs. In the development part, with the microcontroller programmed by ourselves, the peak pressure of the inhalation and exhalation could be maintain between 0 – 4 mmH2O when the breathing flow is below 30 L/min. With a fit blower and motor exhalation valve connected to the microcontroller programmed by ourselves, the fan and motor exhalation valve can work efficiently and response instantaneously to every pressure change of a breathing cycle. The new system not only solve the problem with too high static pressure caused by the excessive air flow supplied by the blower, but peak pressure of exhalation decreases substantially because the motor exhalation valve will open automatically when we are in exhalation, and then enhance the comfort level of BR-PAPRs. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/78291 |
DOI: | 10.6342/NTU202002717 |
全文授權: | 有償授權 |
顯示於系所單位: | 環境與職業健康科學研究所 |
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