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V4 Fume Extraction
- This topic has 37 replies, 10 voices, and was last updated 2 years ago by
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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
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
[2] Removal of VOCs from polluted air
[3] Evaluation of GAC filters to remove VOCs
Attachments:
@s2019 Yes you can use this regulation: The maximum 3-hour concentration of hydrocarbon content is 0.24 ppm, not to be exceeded for more than a year [2].
And yes we should post the summary here on the forum. I am also working on the download kit information atm. Progress could be slow because I am doing it part time as I am not at Precious Plastic V4 office anymore. But I will most definitely post a summary here on this thread 🙂
@s2019 sorry for late reply! Yeah you can compare my results to the US regulation I mentioned in my first post. But there are many regulations present and it was quite hard to discern which one is of use. Right now, I am writing the download kit information, so you can read from download kit. It may be more elaborate 🙂
Hi All,
Im looking into a way to indicate the amount of VOC’s in the air
planning to use the CCS811 sensor together with an arduino.
Will update a bit
Attachments:
@jerzeek, great ! I was waiting for this. I am just puzzled how those sensors compare to 200$ units. Anyways, I am adding this to the PP firmware and our units as default but will wait for some more data.
thanks
@ppme
I think it is mostly because these sensors are accurately calibrated to known sources and have other sensors (temp hum etc. ) to ensure the quality
Right,
so what would be the best strategy to add this to machines as standard – addon ? I’d prefer this as mobile device too btw.
For now these things come to mind :
1. purchase a pro hand held device
2. measure normal conditions
3. measure non – plastic fume but other conditions (ie: welding)
4. calculate a base line for zero out of 2. and 3.
5. do smaller melts – in an open and near closed workspace
6. do bigger melts – in an open and near closed workspace
7. do some ventilation to see how the sensors react
After this, we should be able to qualify the cheap and better sensor. I guess I have to measure this also from different points in the room to extract a kind of ‘distance factor’.
I think the easier way is to tell folks to get as much clean air as possible – plus extra safety gear.
Originally I was hoping that when the V4 team had rented the professional machine, they could do a side by side measurement using the low cost sensor, mainly for information. I don’t think you can certify the air safe with one of these unless you do some serious lab work. Too much is unknown.
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