Documents

• 1: Protection
• 1.1: Powered Respirator
• 1.1.1: Materials
• 1.2:
• 2: Organizing

1 - Protection

1.1 - Powered Respirator

Overview

This cost-effective PAPR (powered air purifying respirator) typically scores between 1,000 to 6,000 on my PortaCount 8020, which corresponds to a filtration efficiency of 99.98%. By comparison, a fit score of 200 is typical for the popular 3M Aura 9205+, which is considered high enough for use in health care settings. Anything over 500 will put you in rarefied air, as it were.

Powered Air Purifying Respirators (PAPRs) offer a significant advantage in respiratory protection by providing lower breathing resistance, exceptional filtration efficiency, and positive air pressure, which prevents contaminants from entering the mask even in the presence of leaks.

This build has completely changed my life, allowing me to comfortably wear a mask during exercise, and for much longer than before. I have helped people move while masked. I can feel confident about my protection in crowded places. The mask breathes so well that I don’t need a separate setup for use outdoors.

Use these instructions to create your own lightweight PAPR.

The Broad AirPro

This build is based off of the Broad AirPro, a lightweight and budget-friendly PAPR suitable for most residential/commercial settings. Off the shelf, however, the unit has leaks. Without modifications, it achieves a fit score of around 40, far below the standard required for effective protection.

The HEPA filters that come with the unit, however, are H13 rated, a very high filtration efficiency. To fully realize this potential, modifications are necessary.

Plug the leaks

Refer to these instructions to plug up the leaks of the Broad AirPro and achieve the full filtration efficiency that the unit is capable of.

There are a few major sources of leakage that allow unfiltered air to enter the chamber. These leaks were found using the PortaCount 8020. Every one of them must be plugged.

Please refer to the materials page for a complete list of materials and costs.

Power Button

Cover the power button with a square of 3M Nexcare Blister Prevention Tape. This tape is chosen for its flexibility and water-resistance.

Any flexible and water-resistant tape will work for this mod.

Charging Port

The charging port must be permanently covered. We will use a magnet charging adapter that fits into the micro USB port. This allows you to close off the air to the port and charge the battery.

Start by installing the magnetic charging adapter.

Lay a strip of poster putty around the adapter. Using a combination of finger pressure and toothpicks, smush the putty against the adapter and case to form a seal.

Alternatively, hot glue may be used. For maintenance, hot glue can be removed using a dash of isopropyl alcohol.

Here is the unit with charging cable attached:

LED Panel

The tiny holes for the LED panel must be covered. These holes make a very big difference on fit tests. Cover the LED panel with Scotch Heavy Duty Shipping Tape, or any tape with good visual clarity.

It’s important to keep the tape inside the oval. Any tape that hangs over the edge of the oval can be levered off by pressing on it, and invites the ingress of oil/grease which will dissolve the adhesive. If you have a hard time cutting and applying a small piece of tape, consider using clear nail polish.

Battery Cover

Even though the cracks look thin, the battery cover is a major source of leakage.

We can seal this leak using tape. We will use blue masking tape for demonstration purposes. Instead, you should use packing tape, or any airtight tape for your build. The tape must be thin, or else overlapping tape creates a channel for air leakage.

Electrical tape is not recommended. Over time, heat melts the electrical tape causing black sludge to seep out of the edges.

Lay a strip of tape across the top of the battery cover, with about 1/4 inch of overhang. Press the sides down.

Surround the sides of the battery cover in tape.

Cut off the excess tape.

For a smoother look, you can take the tape off and then flip it so that machine edge lines up with the case edge.

The battery cover is now sealed.

PCB

If the other leaks are plugged, then this is optional. I still recommend taking this step as a failsafe to ensure that air takes a direct route from the filter to the blower.

Pop open the front cover and take out the HEPA filter.

Lay down stretches of poster putty, starting with the edges. Do not cover the black gasket seal.

Lay down more putty until the PCB is fully covered.

Using a combo of finger pressure, a smooth pen cap, and a toothpick, shape the putty to close off gaps.

HEPA filter

Re-install the HEPA filter. Refer to the materials page for replacement filters that meet the H13 filtration standard.

Use thin strips of poster putty and seal the edges above the rim. Stay clear of the white case so that the cover can close flush to the case.

Finish by closing the cover over the HEPA filter.

Secure the hose

The hose comes loose too easily at the base. You can secure it using a retaining ring made from a Velcro cable tie.

Simply install the hose, and then cinch the cable tie around the hose, with fuzzy side out.

The hose is now secured.

Attach to the mask

The hose can be attached to any mask as long as there’s enough tension on the strap to hold the weight of the hose. My favorite mask for this setup is the Drager X-plore 1950 M/L with a strap taken from the Envo Mask Pro.

If using a trifold mask: the tube should be mounted on the bottom fold. To demonstrate, here’s the bottom of a 3M Aura 9010+ with a 11 mm hole punched using a leather hole punch.

The Board AirPro comes with a hose connector that might come loose while wearing the mask.

A more secure connection [is available here] (https://a.co/d/iDBuav8) (# 1/2” Thru-Bulk Bulkhead Plastic Hose Barb Fittings Union Adapter Fittings for Aquarium Fuel Gas Liquid Air with washers).

However, this connector requires cutting off the non-threaded end, as shown here:

Once removed, it can be installed by screwing in the included nut.

Attach the harness

While the blower unit is lightweight, it must be secured to the body to prevent kinks in the hose.

We recommend the following method of attachment:

34-59 inch leather purse strap. (To wear around the shoulder.) Half inch elastic band. (To attach the blower unit to the strap.) Purchase links are in the materials page.

The unit with harness:

How it looks when mounted (with leather cover and black hose):

I recommend that the blower unit is mounted with the HEPA filter facing towards the body. This convolutes the pathway for contaminated air to reach the filter, and mixes in cleaner air on its way to the filter, and has minimal impact on air pressure.

Check that it works

Since breathing resistance is close to zero, wearing this setup is indistinguishable from wearing a mask with a hole in it. One way to confirm that the mask is set up correctly is to squeeze the air hose. If you feel your breath build up, then you can be reasonably sure that your setup has a good seal.

Failsafes

If the battery runs out, the blower unit continues to filter air passively. Fit scores resemble the fit score of the mask alone. As the blower speed increases from low to high, the effect of the HEPA unit takes over, but does not follow a linear increase in fit score. Generally, medium speed provides the best balance in filtration efficiency, breathability, and pressure. Again, air pressure is important because this alone can prevent contaminants from entering the mask, irrespective of the rating of the HEPA filter.

At medium speed, the battery should last 8 hours. Halfway through a work day, you may attach a USB power bank via magnetic charger to the blower. The blower can charge while it provides air pressure. This is called pass-through operation, and is an important component to the Broad AirPro’s safety profile.

If attached properly, the hose should support the weight of the blower unit, so that in case it detaches from the harness, you don’t lose filtration. In the event that the hose and blower detach from each other, you can pinch the hose closed, preventing unfiltered air from entering the mask. This buys you time to get to safety.

If the hose detaches from the mask, plug the mask with your thumb and get to safety.

Risks

Since you don’t smell your own breath, you can’t tell if your mask has gotten stale. There’s nothing wrong with staleness, but it’s a proxy for other things: looser strap, limp filtration material, degraded foam padding. In short, a worse fit. You have to remember to replace your mask. After one month of using the same Dräger X-Plore 1950 M/L in this setup, fit scores look good with the blower on, and look bad with the blower off. Set reminders to change the mask every few weeks.

A word on backyard firepits. While it’s tempting to wear this to a backyard gathering, even a brief exposure to smoke-filled air will make the unit smell for weeks, and cut the usable life of the filter short. Consider wearing a passively filtered mask instead.

When to change the filter

Fit scores show that the H13 HEPA filter continues to do its job for at least 1 year with medium usage.

Meltblown filters never stop working. In fact, they get better the more particles they trap. With a clogged filter, however, the blower might lose air pressure, even while filtration efficiency remains nominal.

Replace the filter once it looks gray, develops a smell, or when the air pressure seems weaker.

Conclusion

And there you have it, your very own powered respirator.

1.1.1 - Materials

All prices are approximate in USD.

Main Respirator Unit

Harness

Replacement Hepa Filters

The HEPA filter is an important component of filtration. If these directions are followed properly, then the fit score of the blower depends solely on the filtration efficiency of the filter.

In my experience, only Broad Air’s OEM replacement filters consistently score above 500 on fit tests. Other manufacturers make replacement filters for the Broad AirPro, and are to be used at your own risk and discretion. Tested fit scores ranges are posted here.

Masks

The following masks are recommended for their superior fit test scores (across many mask wearers) and availability.

Products from these sellers are personally tested with a PortaCount 8020.

Optional

1.2 -

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2 - Organizing

A mess is really just items in transit.

• Organizing a room makes it messier at first because more items are going into transit.

Every item has a home.

• Things can move closer to home without going all the way there.
• It’s comfortable enough for the item to be in the home’s vicinity.
• An item’s home tends to be where it wants to be, and it’s often best not to fight that.
• If you lose an item, the first place you look is a good sign of where that item’s home should be.

Items take the bus to get home

• The “bus” is a box that makes stops where items get off.
• There can be many circulating busses.
• It often makes sense to have an “express bus” which is designated for a distant place with few stops.
• An item that’s not on a bus is a “pedestrian” and it has to walk all the way home. Every item needs a “hand holder” to get home. Hence, very few of them can walk at once, since the hand holder only has two hands. When there are too many pedestrians, traffic comes to a complete halt, and the room stays disorganized.
• An item’s home is very often a container or box with a label on it.

Some items are light enough to go on a “flight.”

• Clothes and trash are examples.
• Just toss the item towards their destination.

When an item doesn’t have a home, it goes into the “Lost and Found.”

• These items can be retrieved later and put in transit once they have a home.

Every item has gravity that attracts related items.

• For example, DVDs enjoy being with other DVDs, as well as game controllers, remote control, etc.
• These will orbit the TV.
• Just like gravity, items drift to their preferred place of orbit.
• An item’s orbit suggests its home.

A mass of disordered items in one place is called a Gemba.

• At a Gemba, items are sorted by their gravity, boarded onto a bus to send home, or moved home.
• Busses are set for departure.
• A Gemba is a temporary transit hub. When leaving a Gemba, busses can go to their next stop.
• A Gemba is closed out when most items have been sorted.

The room is organized once most items are at home and no longer in transit.

• Time to relax.

Supplies

Tips and Tricks

• Generally, boxes with open tops work better for busses.
• Boxes with lids work better for homes, since they can be stacked to save space.
• A bus can be converted into a home by adding a label, and then parking it.

Take Five

To overcome inertia from a large work pile, it can help to use a “Take Five” approach. Instead of processing the load at once, select five items to be processed / loaded on buses / offloaded / sent home.

This makes the work discrete rather than continuous, lowers the threshold for getting things done, and enables processing things out of order.

Knolling

In a disordered state, it can be hard to see items individually and properly assess where they need to go. Knolling is the act of arranging items at 90 degrees, spaced evenly. This can help indicate that an item is at home and at rest, while also revealing items that are out of place. As such, knolling is a method to surface the items that need to be put in transit.

Transportation is a Cost

Organizing isn’t free. Time is the universal cost to create and maintain any state of existence. On a more granular scale, transportation is the cost, because it requires time, physical movement, and physical space for the vessel of transport. In lean manufacturing, unnecessary transportation is considered a fundamental waste. A screw is considered to be in transit until it’s fully driven into the part.

Transportation must be reduced in order to maintain a state of organization.

• Place high-use items out in the open.
• Archive low-use items and at the edges of living space, so that they don’t impede movement and traffic.
• Maximize busses, minimize pedestrians.
• You may downsize, as detailed below.

Downsizing

• The major risk of downsizing is regret.
• Don’t downsize items where the risk is greatest.
• One trick to overcoming a sense of loss is to take a photo of an item before discarding, especially if the item is materially worthless.