Diy N95 Powered Air Purifying Respirator (PAPR)
by ThomasT175 in Workshop > Woodworking
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Diy N95 Powered Air Purifying Respirator (PAPR)
I used a 3M Versaflo Respiratory Faceshield and Breathing Tube for this project, but it can be modified for other systems. I am also using a Ryobi ONE+ 18V battery, but adapters can be found for other batteries - anything larger than 12V will likely need a buck converter to drop the voltage to the rating of the fans. The filters used in this design are 3M N95 Respirator Filter, model 5N11.
https://youtu.be/vyb2oyUVRu8
Supplies
· DROK Boost Buck Converter 9V-36V to 12V 3A 36W Plastic Shell Waterproof Auto Step Up Down Voltage Regulator 12V Volt Transformer for Car Audio Solar Power System LCD Television LED Display Screen
· Ecarke for Power Wheels Adaptor for Ryobi 18V One+ P108 P107 P102 Battery Dock Power Connector RC Toy & Car,e-Bike 12 Gauge Robotics（with Wire Terminals)
· SAE Power Socket Sidewall Port Connector Extension 16AWG Cable, 2 Pin SAE To SAE Weatherproof Quick Connect Plug for Solar Generator Battery Charger, Pack of 2
· AAOTOKK SAE Extension Cable 16 AWG Wire Harness 12V-24V DC SAE to SAE Cable with Switch Quick Connect/Disconnect Snap Action Cable for Motorcycle Cars,Camp Trailer Solar Panels(2.4m/7.8ft-Switch)
· UTUO Brushless 12V DC Blower Fan, 120mm (120×120×32mm) Sleeve Bearing Low Noise Air Exhaust Vent Cooling Radial Centrifugal Flow Blower with 2 Pin Plug, Light Weight
· 3M N95 Respirator Filter, 5N11, Disposable, Helps Protect Against Non-Oil Based Particulates, Use With 3M 5000 Series Respirators or 6000 Series Gas and Vapor Cartridges, 10 Pack
· Hotop 3 Pcs Brass Key Ring Clip Simple U Keychain Solid Belt Hook Chain Purse Ring Holder Gold Loop for Men Women
· Picture Hangers Youliang 20pcs Triangle D Ring Photo Frame Hooks Hanging Picture Oil Painting Mirror Picture Frame Art Hanger Work Hanging Photo Wall Hook
· ERKOON 10/20 Pack Terminal Block, 12-Position Dual Row Terminal Strip Screw Terminal Electric Barrier Block for Small Home Projects and Electrical 10Amp 360V (10)
· RELIABILT 1/4-in x 6-in x 4-ft Unfinished Poplar Board (Item #1228 | Model #POPSRL146SU04)
Building the Box
I have included PDF, SVG, and LBRN2 cutsheet files for the box setup, dimensions are included to validate the output dimensions. If used, I recommend rearranging the components to be more efficiently cut. The boxes can be constructed using other means and layouts, these are just the final products I ended up with and refined for sharing. I also have a YouTube video showing the final layout, details, and use.
I did not include the hinges and latches, as these are a homebrew design and many other options are available.
In constructing the box, the critical dimensions are for the fan compartments, exhaust ports, and the hose adapter port. 120mm by 120mm blower fans were selected due to the compact design and exhaust flowrate with minimal noise. I trialed a box style fan, but with the discharge restrictions it ended up recirculating on itself and produced little forward flow. The design in the cutsheets use a tab configuration - the primary portions of the box use 6mm or 1/4 boards (I used poplar for weight and ease of workability), 2mm hobby plywood was use for the filter retainers. In my project I mis-measured the height of the fans (they were not level and I did not get a good measurement at the highest points) and ended up about two millimeters short - I ran my fans through a thickness sander but modified the plans to account for this. A shim or padding may be needed due to this additional depth of the box.
I used wood glue for fitting the box together and used a bit extra on the inside to aid in sealing the box joints. Hinges and hasps were added to ensure the lid fits tightly to the box.
The hose adapter port is sized to be a slight compression fit with the hose before the seal - if it is desired to insert up to the hose, the dimensions on the cutsheet or sanding/filing may be needed. I rounded off the edges and corners to keep from having sharp corners jabbing into me and added feet to allow the piece to be set down without undue damage. I also added a keyring clip to the back to allow it to easily be attached to my shop apron (the hose it too short for my height to hook to my belt or pockets).
I did originally make a model that used one fan - and this works, but having two fans provides some additional cooling flow and helps prevent fogging inside the hood.
Installing the Fans
Since the fans are not truly 120mm by 120mm, shims may be needed to ensure a 'snug' fit of the fan to the exhaust port. I will also be using electrical tape or other flexible material around the exhaust port to get a better seal. I also filed a small port on the top of the fan so the power wires could enter the exhaust chamber (where I make the electrical connections) and taped the wires to the fan so they would not move during installation or removal.
Powering It
I used an SAE power socket, after modifying it to fit in the space available, and used small terminal connectors to connect the fans in parallel to the power source so each would see 12VDC. Other means of connecting the wires can include lugs, crimps, solder, wire nuts, etc. I have had these terminal connectors for a while and used what I had available but included a link below to something similar.
For power, I soldered a buck converter input to the Ryobi battery adapter (though other connections could be used - I was just saving space for a future box to be built around the battery and converter). I then connected buck converter output to an SAE extension cable (the one I used has a built in on/off switch which has proved useful). Battery consumption is minimal from the use I have put it through thus far.