DIY HEPA Air Purifier (Lasercut + 3D-print)

by StevenVB

8.5K6712

Intro: DIY HEPA Air Purifier (Lasercut + 3D-print)

After having seen IanVanMoruik his Open Source Air purifier I decided to make a similar device. https://www.instructables.com/id/OPEN-SOURCE-AIR-P...

I include some basic steps in order for you to replicate the air-purifier. However, the main goal is not providing a full detailed construction overview, but showing that using some cheap parts together with some Fusion 360 creativity can result in an actual working air purifier.

I've tested the air purfier with a PM sensor and the results are positive (see testing).



STEP 1: Acquire a Cylindric HEPA Filter (€9.99)

After hours of searching for a cheap certified HEPA filter I finally came across a German manufacturer Albatros that at that time offered a cylindric model of 22.4 cm in height and 19.2 in diameter. This model is used for industrial vacuum cleaners so it should provide an actual air cleaning effect (tested and confirmed). The inner diameter however within the rubber band is only 15cm. In order for a larger fan to be used together with a higher airflow rate and naturally a higher diameter, a funnel needs to be created.

Specifications:

  1. HEPA certified
  2. Inner diameter (rubber ring): 15cm
  3. Outer diameter (rubber ring border): 19.2cm
  4. Height (from bottom to top of rubber ring): 22.4cm

Pros:

  1. Certified Hepa filter, you know it will actually filter particles (tested it).
  2. Probably cheaper than producing it on your own.
  3. High structural quality (strong internal mesh support).
  4. I prefer a cylindric HEPA filter as these guys look more space efficient when compared to a flat hepa filter with just a fan strapped onto it.

Cons:

  1. "Not fully DIY".

Shop-URL:https://www.albatros-shop.de/waschsauger/hepa-filt...

STEP 2: Acquire a Fan With a High Airflowrate (CFM, €21.95)

BitFenix Spectre Pro Led 230mm pc case fan:

For this build I was looking for a relativily quiet fan that still provided above average static pressure and a high airflow rate.

Specifications:

  1. Airflow rate: 156 CFM or 4.4m³/min. Thats an impressive 4400 one liter bricks of air passing through the fan every single minute.
  2. Static Pressure: (mmH2O)1.81 mm
  3. Noise: 25.6 dB(A), relatively low as it has enormous fan blades, for a pc fan.
  4. Power consumption: Knowing the estimated Amperage of 0.41A and using it at 12V would give us a an hourly consumption of +- 5Wh.

Pros:

  1. High airflow rate & static pressure
  2. Pretty silent

Cons:

  1. This thing is pretty huge
  2. Is more expensive then a normal 120mm pc fan.

Product info: https://www.bitfenix.com/global/en/products/access...
Store-URL:https://www.megekko.nl/product/0/952057/BitFenix-S...

STEP 3: Acquire a Simple DC Power Adapter (12V, € 13.85)

To be able to choose the fan-speed I bought a simple Universal DC power adapter on amazon together with some simple female 5.5x2.1 adapters to connect the fan to.

Pros:

  1. Voltage can be changed to increase or decrease the RPM of the fan, thus increase its airflow (from 5V to 15V, 2.4A to 1.5A respectively).
  2. Fine build quality and a lot of included adapters.

Cons:

  1. More expensive then a simple 12V DC adapter.

Shop-URL: https://www.amazon.de/gp/product/B01MFCR6W2/ref=oh...

STEP 4: 3D Printed Air Funnel (+- €5).

Finally we can start creating something to connect all our components. I needed some sort of air funnel between the fan and the filter to compensate for the diameter difference (from 15cm to +-19cm). I've created a very simple funnel in Fusion 360. Included the .STL in here. Took +- 4 hours to print.

I attached the funnel to the fan with some simple hot glue.

STEP 5: Lasercut Frame (approx. €12)


I've created a simple design in Fusion 360 that relies on 2 rings that are made out of 4mm thick Berk wood, and 50 blade components which are 3mm MDF. The Fusion 360 archive files are included so you can personalize it to your needs. There are many online guides to convert these models to DXF for a laser cutter.

As you can see in one of the first build attempts the blades are supposed to be skewed and rest upon the ring. The assembly process is pretty difficult and I recommend doing it as follows:

  1. Assemble 3 blades in 3 parts of the circle without any glue.
  2. Iteratively add a blade to each part untill the structure is filled up.
  3. Now we take out a blade one by one.
    1. Add some wood glue to the cutouts/slots
    2. Put it back into its position and keep it there for a solid minute.
  4. Repeat for all blades.

The hardest part is just fitting them together without glue, once the glue is applied it stands rock solid.

DXF Conversion:https://www.autodesk.com/products/fusion-360/blog/...

Thank you FabLab Brussels for providing a work environment, materials & help for students.

http://www.fablab-brussels.be/fablab/



STEP 6: Testing (€ 20)


Once the assembly of the frame is done we simply put in the filter with the assembled fan and funnel and its done. Pretty straightforward. The big question however is; does it actually work?

To answer this question I bought a Plantower PMS7003 sensor from aliexpress. Wrote some code (https://github.com/vandenbroucke/PlantowerCSVLogger) and tested it within a near perfectly sealed closet.

I gather a lot of dust from above my closets and sprayed it within the test cabin together with some aereosols (propane & butane). My goal target was around 100µ/m³ of PM2.5 to start the tests with.

The tests clearly indicate that the filter does in fact work and provides an air cleaning effect. You can also very clearly see when tapping the filter (video) after 3 days of usage that a lot of dust comes loose which indicates that it has actually done something.

After the tests were done inside the chamber the air within the test chamber was "cleaner" or less polluted then the air outside. We can clearly see the difference as we opened our test chamber after testing the filter.

Plantower PMS7003:

8 Comments

Oneida Arteaga 3 years ago

Hi, thanks for this post.
Could you provide the parts that were used in the sensor PMS 7003 ?

mikaelhg 5 years ago

If you don't have access to a 3D printer, or wish to test the concept before printing the part, hardware stores sell generic products called "ducting reducers", which you can either purchase in the generic form, which is just a length of PVC pipe that alternates between ever-smaller funnel, and ever-smaller pipe. You can just cut the generic reducer at the size which matches your incoming and your outgoing pipes. You can also look for a reducer that already comes in your desired sizes, such as 15 cm to 20 cm.

radziu.k 6 years ago

Hello,

Great design, I ordered a filter, fan and power supply. I only have problems exporting (scaling) DXF files to laser cutouts. Could you share DXF files? Thank you.

VincentB65 6 years ago

It looks awesome, thanks !

I'm interested in building it, but how do you connect the DC charger to the 3pins connector of the fan ?

Thanks again !

ad5000 6 years ago

So just out of curiosity here to minimize the size of this some if I were to use two 120mm fans with let's say 80cfm stacked on top of one another would that double my cfm (air flow) or would it just do nothing?

StevenVB 6 years ago

Hey ad5000,

Stacking two identical fans will just result in an increase in static pressure, but pretty much won't increase peak air flow. I would definetly recommend using the largest possible, as these often come with higher CFM and produce much less noise. Good luck!

Steven

Swansong 6 years ago

That's a neat design :) We like to keep an air filter running in the house because of the pets.

StevenVB 6 years ago

Thank you! For your application I would advice to add a thin layer of active carbon just strapped around the filter with a rubber band. This would help with smells :)