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Topic Tag: filter

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Hey community, I’m Suvda, chemical engineer working on PP V4 fume extraction. In this post, I will include information about the amount and contents of the fumes created. I found out which respirators are suitable to protect ourselves. Now, I am finding out which filters and ventilation design is suitable for us. In July, me and @pauldufour will build the fume extraction system. From August, we will test its efficiency with a fume detector and document the results. If you have any questions or recommendations, feel free to comment on this thread or send a message to me.   Fume formation Fumes are created usually due to thermal, mechanical and oxidative degradation. The fumes are mainly made up of Volatile Organic Compounds (VOCs). VOCs are organic compounds that have boiling points roughly in the range of 50 to 250 °C. VOCs might be produced at 150-300C, due to the aging, long thermal exposure, intrinsic sensitivity and the interactions between additives and polymers.   Fume content and amount In V4, we are working with HDPE, PP and PS. PS creates 8 times more fumes than PP and 17 times more fumes than PE. PP and PE are essentially refined wax, that’s why it has less fumes. PS fume contains mostly styrene and other similar aromatics. PP and HDPE mostly emit some alkane vapors. HDPE is the safest material in terms of fume creation. (picture below) PS fume = 470 ± 100 mg/m3 PP fume = 59 ± 14 mg/m3 HDPE fume = 2.8 ± 2.4 mg/m3  [1] Regulation: The maximum 3-hour concentration of hydrocarbon content is 0.24 ppm, not to be exceeded for more than a year [2]. In conclusion, our biggest threat is styrene vapor formed from PS melting.   Respirator filter We need ABEK1 6059 3M filters for filtering organic vapors which have boiling points above 65C, ammonia, acid and inorganic gases, this includes our fumes from melting plastic. These filters can be used for 6 hours continuously in one go, overall maximum of 50 hours and should be stored in airtight container while not in use. We used simple circles to indicate how many hours we have used the mask. Mask side is needed for particulate filter for preventing fine dust to enter the filter of the respirator. Respirator parts: Filter Reusable half mask Filter retainer Mask side   Fume detector VOC detector is needed to check efficiency of filter and ventilation. Photo-Ionization detector (PID) is the most commonly used technology to detect VOC content in the air. When air enters the end of a VOC meter, a UV light interacts with the molecules in the air. Organic compounds release positively charged ions when they pass through the light, which are then captured by a negatively charged plate producing measurable electrical current. For us UV lamp of 10.6eV is suitable. At V4, we are planning to rent a PID detector for a week. Their primary use is for monitoring possible worker exposure to volatile VOCs. Gas detection tubes are useful for detecting the presence of specific gases such as styrene.   Ventilation LEV is Local Exhaust Ventilation which is a standard for industry to ventilate the toxic air efficiently. Hood: contaminant cloud enters the LEV Ducting: Conducts air and the contaminant from the hood to the discharge point. Air cleaner: filters or cleans the extracted air. Discharge: releases extracted air to a safe place For temporary measure, we are using fume caddie for fume extraction of sheet press (pics below). Filter For VOCs the cleanest, easiest cleaning method is via activated carbon filter (ACF) especially granular ACF and fibrous ACF. Activated carbon has big surface area due to a lot of pores where VOC molecules can get trapped, thus filtered. ACF remove following VOCs very well: toluene, xylene, styrene, alcohol, benzene, decane, ethylbenzene, heptane and octane. And the following gases well: pentane, acetone, hexane [3]. Porosity is the most determining feature of activated carbons. This week, we would like to find the suitable ACF to install above the extrusion machine. If you have any recommendations and suggestions, do not hesitate to send me a message :)   Resources used  [1] Pollution characteristics and health risk assessment of VOCs emitted from different plastic solid waste [2] Removal of VOCs from polluted air        [3] Evaluation of GAC filters to remove VOCs            
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