Air Purifier
Intro: Air Purifier
This is a powerfull air purifier which use G4 and F7 filter. The HEPA F7 filter is sufficient to stop pollens. This air purifier is intended to clean the air of a big room during allergic periods.
STEP 1: Hardware
The fan as been chosen from the requisites of the filters. The filters are rated for a amount of air flow and oppose some resistance. When they get dirty, the resistance increase as well. The fan is powerfull enough to deliver air pressure up to the max rated by the filters.
I made a mistake when buying the fan. It is no dimable. It's either full power (and noisy) or off.
The fan is inside a crate, creating a depression behind the filters and the exhaust is located one one side.
STEP 2: Building the Crate
The fan is fixed inside a crate. It's made with laser cut 5mm plywood. Because the fan is quite heavy, and a rest for the filters is needed, the bottom of the crate is reinforced with wood pieces. Carrefully cuted with the same length, it wasn't correctly pushed to the maximum. I used wood paste to fill the gape and avoid any air leaking possibility.
STEP 3: Exhaust
Since I used some foam to try to reduce vibrations and noise, it wasn't very easy to cut the exhaust a the rigth place with the laser cutting machine. I did it with a drill. Not very clean but it won't be visible.
STEP 4: Fixing the Fan
Every contact surface of the fan is using foam in a desperate attempt to lower the noise. Because the fan is quite heavy, it was necessary to have two points of contact. A laser cutted piece of wood is used for the exhaust. The bolds are pointing outside, I kept them like this because I will build a silencer for the exhaust and th bolds are very usefull to fix this extension later.
STEP 5: Sealing the Crate
To ensure that the low pressure chamber gets air through the filter, I used some putty. The electric cord is also a weak point. I drilled a hole smaller than the diameter of the cord and slightly enlarge it with a file. It fits perfectly.
STEP 6: Electric Box
The electric box is glued on the back of the crate. Since the fan is not dimable, I used a simple on/off switch. Some velcro band are used ton fix the electric cord. I drilled some holes in case of heating issues but I did it on the sides of the box which is not the best choice .
STEP 7: Inserting the Filter
The H7 filter is seated on a wooden square which is seated on the wooden pieces that also give more strength to the crate. Some ruber band sold to seal windows or doors is used to seal the sides of the H7 filter.
The last filter is just pushed inside the crate. The size is the same. Friction easily keep the filter in place.
To close the crate a more or less pretty grid has been laser cutted. It offers too much air resistance and needs a real fixing system.
37 Comments
Amaries 6 years ago
Nice idea and beautiful design, thank you for sharing!
JoãoP142 6 years ago
Luk--- 6 years ago
JoãoP142 6 years ago
And try to search a bit of it, since it can benefit your project.
Luk--- 6 years ago
JohnC430 6 years ago
Luk--- 6 years ago
d_talker 6 years ago
Hi! What about noize? What about PM 2.5?
Luk--- 6 years ago
A thiner filter would be necessary, E12 or better I guess. I'm not an expert.
Luk--- 6 years ago
It's very loud. The fan constructor is announcing 70db. I strongly recommend to chose a variable fan. I clearly made a mistake on this.
RumblePirate 6 years ago
zonkerharris 6 years ago
Most home fans or air filters have fans which are powered from the AC wall socket power, and may have 1, 2, or 3 speeds selected with a switch. But, you can get DC powered fans (recycled from computer power supplies, for example) which have Tachometer and PWM speed control wires. Such fans have red, black, yellow and blue wires.
An Arduino (or other embedded controller) can use a PWM output to control the speed. This could be as simple as using an ATtiny85 to read an analog input from a potentiometer between 5v and ground, and map that reading to the PWM output pin, and you'd have a simple speed control.
The solution above, with a DC fan, combined with these construction ideas, might be a good fit. Maybe adding a barometric sensor inside the box could tell you when the filter is getting clogged (and the fan is working harder to pull the air), or use the tachometer reading at various PWM settings (compare no filter, new filter to get readings) and then set comparisons in the code to light an LED to change the filter. That may be a fun weekend project!
Luk--- 6 years ago
nex_otaku 6 years ago
Very nice!
What is the cost of total build and parts?
Luk--- 6 years ago
I had other ideas, too complex so I spent more than that but the model itself should not be more than 250€, probably less.
Tasmaniac 6 years ago
Please note, "cutted" is NOT a word. The past participle of 'cut' is 'cut'.
Luk--- 6 years ago
TheArduinoGuy 6 years ago
Why can it not be controlled with PWM ?
Luk--- 6 years ago
I have very limited knoledge in electricity and none in electronics (I've just searched PWM).
I guess the fan has an induction motor. It was featured with a control device (the black thing in the electrical box).
Maybe it is controllable by PWM but it's far from my skills for now.
Thank you for your concern.
diy_bloke 6 years ago
I understand it is being fed from the mains grid. Thus cannot be fed bij PWM.
Tou could use a TRIAC to control it by phasecutting. That will most likely work, though TRIACs are not specifically suited to regulate inductive loads