Reflow oven filter - Page 1
Forum section: electronics / general

author: ubbut
author_rank: Regular Contributor
timestamp: September 15, 2020, 08:09:10 am
content: Hi Guys,we have a small reflow oven (BRTRO-420) that maybe runs about once a month for an hour or so. Currently we are blowing the exhaust out of the window, but now would like to install an additional filter to avoid smell and toxic fumes.I looked around, but could only find few solutions, and those were for big ovens that run daily. I wonder if there are filters with less capacity and cost that are sufficient?You can get inline duct HEPA/Activated carbon filters, but those usually don't come with a max temperature spec - and if they do it around 70°C.Any recommendations or experiences? Thanks !

author: kylehunter
author_rank: Regular Contributor
timestamp: September 15, 2020, 08:33:28 am
content: I don't understand. If you are ducting the exhaust outside, why would you filter it first? That's not going to prevent anything inside from smelling any different.

author: ubbut
author_rank: Regular Contributor
timestamp: September 15, 2020, 08:40:59 am
content: I want to avoid toxic fumes and smell for my neighbors

author: Pinkus
author_rank: Frequent Contributor
timestamp: September 15, 2020, 09:28:30 am
content: Some people don't care as soon as it is outside their house, but it seems some people care about environment and neighborsI don't think you will find a filter which will be able to work at 250°C or more. I guess you better measure the temperature at the point where it would enter the filter to have an idea about the real temp.Also you would need a lot of air pressure to press it through the filter. I doubt the reflow oven fan will do it.I do own a ARM-EVAC 250 from Pace. You may use something like this as a filter unit. This unit is able to filter 290m³ (170 cfm) per hour. Just suck in some additional cold air (some extra openings) to bring the overall temperature of the air-mix below the allowed level.

author: mairo
author_rank: Unknown
timestamp: September 15, 2020, 10:31:24 am
content: If it has an exhaust port, you can connect it to a fume extractor. I have done this to an APS Novastar GF-120HT connecting its two exhaust ports to a PACE EVAC 200 fume extractor. If the fume extractor is very strong and do not have suction control, you can have openings just next to the exhaust port on the oven to prevent the extractor from sucking too much from the oven directly.If you are already extracting outside, you can probably put a proper filter in this existing line.

author: ubbut
author_rank: Regular Contributor
timestamp: September 15, 2020, 11:51:09 am
content: The oven's fan only turns on during the cooldown phase and I was going to install an additional duct fan to put the air through the filter.The idea to suck in additional cold air for cooling is brilliant, thank you!If a simple hole is not sufficient, one could even control the airflow with a temperature sensor + servo, ... but let's see if this is necessary.this would allow to use filters such as the ARM-EVAC 250, but also maybe something like this:https://www.aliexpress.com/i/32989721290.html?spm=a2g0x.12057483.1000001.8.3c264a04Up2ljG

author: ace1903
author_rank: Regular Contributor
timestamp: September 15, 2020, 02:11:29 pm
content: I would recommend longer flexible aluminium ducting (~1,5m) to spread the heat before it reach in in the filter.For filter you can check what is used with CO2 laser engravers.I am sure there is some combination that is proven in the practice and cheap enough for hobbyist.

author: mairo
author_rank: Unknown
timestamp: September 15, 2020, 09:31:11 pm
content: Quote from: ace1903 on September 15, 2020, 02:11:29 pmThat is also true. I forgot to mention that on the GF-120HT we do run aluminium duct for this reason. The oven is on a stand and the fume exhaust is on the floor so there is ~ 1.5mm of ducting which is seems enough for the 'small' oven . The cooling also happens at the port connection where as I mentioned there are openings (air ports) that we can vary theirs opening size to allow for different volume of cold air to enter as well - this also acts as cooling and also to allow for air being sucked when the oven ports are closed. These air ports are located below the raised oven's exhaust port opening.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: September 15, 2020, 09:40:55 pm
content: I would keep it simle. Use a relatively cheap and in your area available carbon (or other?) filter.Then add a fan, to suck in lots of false air along with the fumes. The cold air mixes with the fumes from the oven, and the resulting temperature is easy to get below a point where it would matter.

author: S. Petrukhin
author_rank: Super Contributor
timestamp: September 19, 2020, 05:01:53 pm
content: Quote from: ubbut on September 15, 2020, 11:51:09 amYour extra fan will damage the temperature profile. If you do soldering once a month, use a simple air freshener aerosole.

author: ubbut
author_rank: Regular Contributor
timestamp: September 19, 2020, 05:24:56 pm
content: First of all, I want to keep my good health, thank you. This is not about smell.Secondly it won't damage the temperature profile. The fan only turns on during the cooling phase, which is temperature controlled as well, so the fan will turn off if it cools too quickly

author: Rat_Patrol
author_rank: Frequent Contributor
timestamp: September 22, 2020, 09:52:54 pm
content: Think of the reflow oven more like a class B vented gas appliance.Have an open "chamber" or hood over/around the reflow oven with a fan that draws constant ambient air from the room and then whatever fumes are created from the oven. Mixing fumes/smoke/heated air from the oven with ample amounts of ambient room air will lower the temp enough for filtration. There isn't much actual velocity around the reflow oven itself if you design it right.Then filter the air and discharge it.I run this exact setup myself. My setup's hood extends to my hand soldering and rework stations as well. It runs all day during production so it is hell on the air conditioning/heating bill, but cancer is not something I'm excited to deal with so I pay the utility company.