COVID-19 Swim Mask HEPA PAPR

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Introduction: COVID-19 Swim Mask HEPA PAPR

LiPocharging bag*** UPDATE- check out our non-powered filter designs at Covid-19 Swim Mask Non-Powered Filters X 3

***UPDATE 4/13/20 - We are updating our PAPR. We felt that the air flow coming from the computer fan was not enough, so we are using air pumps for inflatable raft toys. With this we hope to increase the volume of filtered air produced to make more positive pressure.

***UPDATE 5/1/20-We fit tested the PAPR unit. The Swim Mask PAPR has undergone in real-world use with excellent results

These are crazy times in the world of the COVID-19 pandemic. In my 24 years as a physician, I could never have imagined a time like now where we as a healthcare community and as a nation would be paralyzed by a disease leading to basic equipment shortages putting myself and colleagues in danger. Long before coronavirus, physicians and healthcare workers are used to putting our own lives and safety at risk in front of sick patients on a regular basis. Now, however, we are confronted with higher exposure risks of contracting the novel coronavirus in the absence of personal protective equipment (PPE). To minimize risk of contracting coronavirus from patients, front line healthcare workers can wear an N95 mask to filter small particulate matter. Unfortunately these masks have recently been in severe shortage. An alternative protective gear is the Powered Air Purifying Respirator (PAPR). A PAPR uses a motorized fan to pass air through a HEPA filter, which removes the contaminant and supplies purified air to a mask or hood. In response to the severe shortage of personal protective equipment that we face to protect ourselves form the novel coronavirus, my son Connor and I have designed and created what we feel is functional PAPR made out of a full face swim mask, tubing, computer fan, HEPA filter and 3D printed parts all powered by a 12v DC pool inflatable pump using by a 11.1v R/C drone battery. The goal was to make a device to protect those who put themselves in harms way to protect others. We wanted to make this mask with objects readily obtainable in the community, and with a few parts made from a 3D printer

Supplies:

Step 1: Choosing the Mask

We purchased a full face adult swim mask from Amazon. We felt that the swim mask designed to keep out water with a watertight seal is well suited to keep out the coronavirus. Our mask, like most full face swim masks, has a silicon valve below the chin where air can escape under positive pressure when you exhale or when pressure builds inside the mask.

We did not place the snorkel that came with the mask as the snorkel opening at the top of the mask would be used as the air intake. We identified the center opening as our air intake, and the lateral openings as exhalation ports. In the previous build we plugged the exhalation ports forcing air out the bottom of the mask only. On version 2, we decided to include the exhalation ports in the new adapter.

Step 2: Fitting Hose to Mask

We printed an adapter for all three holes at the top of the mask to increase air flow with inhalation and exhalation. My son Connor designed the front end of the adapter to fit the intake and exit holes at the top of the mask and the rear end of the adapter to fit the 1 1/8" tubing. The fit is snug from the mask to adapter and also from adapter to tubing, however electrical tape and duct tape can be applied to the junction of the tubing to mask adapter for an airtight seal.

Step 3: Supporting the Hose-mask Joint

The 3D printed mask adapter bridging the hose to the mask’s snorkel opening goes from a large diameter to a smaller one and is at risk for breaking. We wanted to support the hose at this critical juncture. Fortunately our mask, like many other full face masks, had a GoPro attachment on the top. We 3D printed pieces to work with the GoPro attachment and support the hose.

Step 4: Powering the PAPR

Instead of a computer fan, we used a 12v DC air pump for an inflatable raft. After the initial build we tested our 5v fan unit for airflow and found what other users had also discovered, which is the 5v computer fan air flow is too weak. Despite being rated at >30cfm we were not getting these volumes when testing how quick the fan would fill a garbage bag. We spent days trying to tweak the fan output by increased voltage and different power sources, but the community and commentators were correct and the fan output too weak, and we had to abandon the 5v computer fan. In searching for a suitable replacement we came across an old 12v air pump for pool inflatables. These too can can be found almost anywhere in big box stores such as Walmart and Target and also local pool stores and Amazon. It's important to use the 12v DC pump and not a 110v AC pump. If the plug cannot fit the cigarette adapter in a car, DO NOT USE IT because that fan will not work. See the picture above for the the correct type of plug confirming the pump is a 12v DC pump. The 12v plug was cut and removed after identifying which lead was positive and which was negative. The negative wires are connected to the two lateral leads of the adapter. The positive wire is connected to the lead at the tip. The positive and negative leads of the pump were connected to the +/- motor terminals of the potentiometer. This pump gave us more air flow but we needed a higher voltage battery to power the 12v pump. We used a 11.1v lithium polymer (lipo) battery commonly used in RC cars and drones as a power source for the pump. Our battery had a female XT60 connector so we mated it to a male XT60 connector and ran the positive and negative wires to the +/- power terminals of the potentiometer to vary the voltage delivered and control the speed of the fan.

***As an additional safety measure we added a LiPo battery voltage checkerwhich sits on the battery's 'tail' (not shown) to the PAPR unit to continuously monitor the status of the LiPo battery.

Step 5: Setting Up the HEPA Filter

Unfortunately we damaged the vacuum filter of our original build and could not trust that it was a reliable filter adequate for protection from small virus particles. After our initial build and purchase of the vacuum filter cartridge, we could no longer purchase the vacuum filter cartridge either because of the lack of stock or because maybe they had been purchased widely for this purpose. Regardless, we switched to a filter using a cut HEPA grade vacuum bag similar to the design of our HEPA vacuum bag filter in our non-powered design.The new filter design consists of two identical 'cones' attached to the 1 1/8" tubing. One cone attaches to the tubing leading to the pump and the other cone attaches to the tubing leading to the mask. In between the tubing is the smaller cylinder and the 5" diameter cut HEPA grade vacuum bag filter. Using a hamburger analogy, the two cones are the buns and the cylinder is the meat. The HEPA filter is the lettuce. Place them together to have a functional filter where the only air to reach the mask is now filtered by our HEPA vacuum bag. We secured the filter apparatus together with duct tape

Step 6: Putting It All Together

The filtered air hose was attached to the top of the mask.Turn on the fan via the potentiometer and you have your own PAPR. The potentiometer is necessary in this build to control the speed of the pump. At 100% it feels too fast and there is too much flow. The potentiometer setting at 51 (which we assume is 51%) feels like the flow of a traditional, commercial PAPR. The optimal settings however have not been calculated or validated. Again please make and use this device and these recommendations only in crisis mode as a last resort.

***In our non-powered swim mask filter build we used 2 additional filters, 3M P100 and Gibeck Iso-guard HEPA filterto protect against virus. We will make modifications to this version, version 2, of the powered swim mask HEPA filter build to try to use these commercial filters as well.


***As an additional safety measure we added a LiPo battery voltage checker which fits on the battery's 'tail' (not shown) to the PAPR unit to continuously monitor the status of the LiPo battery.

Step 7: Cons:

CONS:

  1. The mask unit is loud. The fan creates a significant noise when running at a speed necessary for adequate air flow
  2. The mask unit has not been formally tested in the laboratory for efficacy and safety. As with our previous mask, we believe in the science and we believe the adapters that were designed and made by my son and I are a solid design. We would like to stress again that the swim mask HEPA PAPR and filters should only be used in PPE shortage crisis mode. ***The swim mask HEPA PAPR underwent unofficial OSHA standardized qualitative fit-testing by me and performed at least equal to an N95 using FT-32 Bitter as an agent. The only PPE tested to fail the qualitative test was the CDC recommended bandana. As a physician however, I know am putting my personal health on the line when I use any homemade device as PPE. I have personally used the swim mask PAPR in real life procedures for several hours and it functioned better than expected. I trust the science, work, and design that went into this build more than I trust the government and hospital systems to provide me and my colleagues with appropriate protection when we need it the most.
  3. The build may be complex depending on your comfort level with electronics and soldering, and 3D printing. Our non-powered swim mask build is less complicated with less parts
  4. LiPo rechargeable battery packs are not common for most and are inherently dangerous. Our original design called for a 5v fan powered by a everyday 5v powerbank, but the 5v fan proved to be too weak. By upgrading our fan we also needed to upgrade the power source to an 11.1v LiPo battery found frequently in R/C drones and cars. LiPo are safe when charged and monitored correctly with a balance charger and a fireproof LiPo bag, but care and respect must be taken when using this high charge density power source. ***We also added a LiPo battery voltage checker to continuously monitor the voltage status and prevent over discharge of the battery which may lead to hazardous results.
  5. You look funny. Let's be honest. To patients we may look ridiculous with this protective equipment but in crisis mode, you use what you have. My brother, an ER physician at a major California health system, is in the frontline in the battle with the coronavirus. Every day at work he is exposed, and in crisis mode he is more than willing to use the swim mask and adapted filter.

Step 8: Thoughts:

This device is sound in concept and theory but has not been tested. This device in no way is meant to replace existing and approved masks and devices such as N95 mask and commercial PAPRs when they are available. If you make this device or use the concepts of a wearable powered HEPA filter you do so at your own risk. This device is designed to be used as a 'crisis capacity strategy' for PPE as defined by the CDC when the surge in demand for PPE leads to severe shortage or unavailability of the approved protective equipment. As a physician I have worn multiple types of N95 masks and PAPRs and I find our mask is easy to use and breathe in. The HEPA filter should successfully filter the coronavirus. Although distance between fibers in the HEPA filter is 0.3 microns and the corona virus is smaller at .12 microns in size, the HEPA is able to filter close to 100% of coronavirus sized particles. The HEPA filter accomplishes this based on the multiple methods of capture the filter uses and the speed of which air is forced through the filter. Almost counter intuitively, the slower the velocity of the air passing through the filter, the more efficient the HEPA filter becomes at removing even the smallest particles in the air. Although very technical, the science behind this concept is illustrated here in this scientific paper by NASA engineers.

We like the use of the swim mask because it works as a face shield and creates a 'airtight' seal around the face. In the event there is not a complete seal, the positive pressure of the PAPR pushes air away from the mask preventing outside particles from gaining access to inside the mask. In addition those who have used a PAPR with the hood know how difficult it is to hear inside the hood with the fan on. Our design leaves the ears outside the mask for better hearing. Because of this design, our mask can be used with a stethoscope, a feat that cannot be accomplished with a traditional PAPR hood. The unit is also easily deconstructed and the mask can be washed with soap and water and/or appropriate cleanser and reused. *** As an aside, it just so happened on day 1 of using the mask in real-world conditions, I was accidentally splashed in the face with body fluids by the staff in the procedure room. Such events are rare, but do happen. Normally this may require stopping the procedure and eye-washing if there is any risk of contact to the eyes, but we were able to continue with a few wipes of disinfectant. After the procedure the mask was washed thoroughly with soap and water and the day continued as planned. Needless to say I was glad to have complete face protection that day compared to the standard a cloth based mask.

This project is a work in progress and will most surely evolve, as does our fight with coronavirus, and we will update the product design as we improve it. Any suggestions or comments are welcome. We understand that this build might not be for everyone as they may not be able to obtain the necessary resources and or have the technical capability to manufacture the device. For those who want to help in our fight I would like to direct you to Team Shield. We have partnered with Team Shield who are a an energetic group of students from Davis and Roseville California that have come up with a surprisingly simple yet brilliant solution to PPE equipment shortages. Their products and equipment are currently in use at Northern California hospitals. Please check them out because through Team Shield anyone can help our frontline healthcare workers by making shields or making donations.

Also we are not alone in innovation in making PPE as a crisis strategy. Please read these excellent articles from Make Magazine explaining how we ended up in crisis mode and a second article showcasing makers around the world sharing innovation to help us all battle coronavirus. As a physician I am not only humbled working next to my son in these projects originally started as a way to protect me and my colleagues facing crisis, but I am also humbled by the every-day makers and do-ers with no ties to healthcare trying to find ways to help healthcare workers and everyone else out of this mess we are in. We will survive, not with the promises of our government and healthcare systems, but in spite of them.

1 Person Made This Project!

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31 Comments

1
KarlS19
KarlS19

10 months ago on Step 4

I'm not sure if it was stated, but you need a brushless DC motor or you will have OZONE in your airstream. I did see some mention CPAP machines, that would be a good pickup on craigslist or eBay for a used one.

0
robertryan
robertryan

1 year ago

GREAT FUNCTIONALITY!

I’m an engineer in San Francisco developing a similar project but using an arduino and barometric sensors to regulate the fan speed (in addition to the pot) plus trigger warnings for low flow or battery. Like you I’m using a vacuum HEPA filter except it’s slightly larger but very common (from a Shark). I’m wondering about the fan you’re using as it I wouldn’t think it can develop the necessary pressure. I’m following the 3M specs and they’re using a fan that can maintain about 1” of water.

I have a variety of prototype face masks including snorkel, CPAP, and full helmet. My understanding is the helmet is actually more comfortable but there are challenges with sourcing components. I’d appreciate getting your ideas and feedback. I would like to have a compliant, functioning prototype with common materials that can be sourced for less than $200. The battery pack is based on a Ryobi tool battery.


0
busydoesitbest
busydoesitbest

Reply 11 months ago

Yeah I think i would just need an adapter for my travel cpap with battery and a filter for exhalation.

I have https://mytranscend.com. I want to print off an adapter for the inhaled to connect to and then a filter for exhaled. and maybe that GoPro strut that was mentioned. The heppa filters are commercially available as are the cpaps.

This has up to a 20cc h20 displacement and operates a under 30 db.

What am I missing here for those to be feasible? Is that not enough positive pressure?

0
qebehsenuef
qebehsenuef

Reply 1 year ago

Thanks for reaching out to us. My son said he replied to your email and hopefully we can help each other make the project better.

0
hallinen
hallinen

Reply 1 year ago

Have you seen the helmets that are being used instead of a mask for CPAP? I wonder if this idea could be modified for that. The outcome data for people going on vents with COVID is grim, worse than regular ARDS from what I'm seeing. I wonder if a helmet type CPAP with a HEPA filter exhaust could be whipped off by all these amazing maker groups. Maybe early CPAP would prove to be better than intubation and all that barotrauma.
I played with an arduino and a hearing aid zinc air battery to make an oxygen sensor for combustion analysis. Some students out of Johns Hopkins did a project for medical oxygen. Maybe a couple pressure sensors, an oxygen sensor, and CO2 sensor would make a functioning helmet/full face mask alternative to intubating everybody and stop the spewing of virus everywhere.

0
robertryan
robertryan

Reply 1 year ago

Update - The HEPA Filter can be found on amazon if you search for “Kenmore EF-2 replacement HEPA”

0
fraser.peter
fraser.peter

11 months ago on Introduction

Hi. These air pumps are very leaky. Just block the inlet with your hand or tape and blow into the outlet, or vice versa. You will have leaking everywhere. The only real way to make them work is to put a filter after the pump. I'm playing around making a papr with one of these and have a Scott P100 canister filter on the inlet then realised the leaky nature of these pumps and so have put another filter inline after the pump. https://solmed.com.au/collections/respiratory-resuscitation/products/flexicare-adult-angled-bacterial-viral-filter-hme-with-tethered-cap-port

Doesn't seem to reduce the flow too much. I think with one of these could probably eliminate the inlet filter entirely.

0
smarrupe
smarrupe

11 months ago

I Think that a cpap muffler could be useful to reduce the noise level Inside the mask

0
georgew93
georgew93

Question 1 year ago on Introduction

Have you considered attaching a 3M P100 particulate filter for reusable respirators onto your powered filter? Other similar adaptors using 3M P100 particulate filter have set a stereo or tandem filter because of difficulty to breathe with p 100. With a air being forced through the filter will make it easier to breathe.

0
qebehsenuef
qebehsenuef

Answer 12 months ago

Yes we have! We think alike. We used the 3M P100 in our non-powered swim mask and just need time to work on adapting that filter to our PAPR motor. We will update when we can. Thanks

0
hernandosalas
hernandosalas

Question 1 year ago

Hi,

I have read that these type of air pumps can’t run for more than 15min. Have you taken that into consideration?. Have you tested what is the duration of the battery you are using with the air pump you mention?. I have tested with different computer fan even ones with high cfm but don’t provide that amount of airflow as the air pump does.

Keep up the amazing job you have done.

0
qebehsenuef
qebehsenuef

Answer 12 months ago

I've opened up several of these airpump fans and found that the motor is a simple barrel type older electric brushed motor. These are cheap motors which I told my son are similar to motors on r/c cars from the 80's when I was kid. These are not the same electric motors on modern r/c cars today which are brushless and can operate for extended periods of time and last a long time, so your concerns are valid. That being said I've run the motor at the airflow similar to a commercial PAPR for 40 minutes at a time without issue. The drain on the 2200mAh 11.1v LiPo battery is less than 1%/min so for this setup I may be able to push go 1.5 hours on a charge. As I write this my son and I are taking apart a old drone to see if its motor which is brushless can operate with less noise and more efficiently.

0
michaelbrody2012
michaelbrody2012

1 year ago

I’m an anesthesiologist; and has intubated multiple covid. And like many we are very short on PAPR.
We did by a full face snorkel mask that inhalation is through anesthesia machine hme 99.999% filter. This works well- but still gets hot; a little fogging.
Our “weak point” of design is exhalation valve on these masks: do we trust them or not. It seems to created a great seal- on inhalation no leak and mask pulled closer to face when snorkel obstructed. But we wonder if tiny amount of air is sucked in during initial split second of inhalation- to activate and close the exhalation valve. So one thing we tried is just to tape over valve from inside of mask to defeat it - so inhalation and expiration is through machine filter - but that gets very humid in mask.
We are working on a powered fan adaption to this. We still wonder if exhalation valve is the weak point in this way: if fan is continuously running, this valve will always be open; when one initiates an inhalational breath, air will be entrained in some quantities from either fresh air fan side ; but also exhalation valve to some extent- probably more so than non- powered fan version.
So what we need is a low pressure reservoir of fresh air as source of clean air for any leaks.
My thought is to :
Put mask on with hose that comes from fan; fan; and then another hose with hepa filter. Located around waistline in the back.
Then put plastic bag over entire head/mask ; cut and tape hole where eyes look out if plastic mask not optically clear enough. Bag needs to go down to shoulders.
So theoretically: this will create enough reservoir for inadvertent inhalation via exhalation valve.
We are also using a 130 cfm 12 volt in line fan; works at lower RPMs with 9 volt batteries. Based on calculations: 3 - 9 volt batteries would give you 30+ minutes-enough for intubation and line placement. And if batteries run out-can either replace in room or just use as a non- fan .
Any constructive criticism appreciated (we have fan and mask; just need to go to Home Depot for hose/connectors ; and figure out how to get more surface area of filter so fan can suck enough through filters

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0
qebehsenuef
qebehsenuef

Reply 1 year ago

Michael we appreciate your comments and have debated these same concepts ourselves. We agree that when using a non-powered respirator such our parallel design the mask is pulled to the face. Without formal testing there is no way to know for sure but we find this is a positive and not a negative It represents confirmation of a good seal around the face. Any risk of inhalation of particles would also occur with any non-powered mask including commercially available ones.
Also,since this original post we have tried to tweak the output of the 5V fan as best as we could. We have come to the realization like yourself that a 12V fan comes closer to deliver the CFM of a commercial PAPR better than the 5V fan powered by the powerbank. This is a shame as it slightly complicates the build for those less tech savvy. We plan to post an update to our instructables soon changing out the 5V computer fan to a 12V pool inflatable fan. Your use of a bilge fan is an excellent idea.

0
qebehsenuef
qebehsenuef

Reply 1 year ago

Michael please see the non-powered mask design for an update. I fit tested the mask designs and they passed the qualitative testing. We will fit test the swim mask PAPR with version 2.0

0
Karmagal
Karmagal

1 year ago

HEPA CAUTION: be careful, so far all the HEPA and air filters (including vacuum cleaner bags and air furnace/home HVAC) have spun glass (aka fiberglass) in them which is fine for house furnace filtering but probably not good in front of your face with pressure from breathing... (cut particles of fiberglass not good). A few threads talked about non-fiberglass stuff from (3M) maker but honestly I'm seeing a Prop 65 warning on those (CA's warning for fiberglass) so waiting to hear back from manufacturer... BE CAREFUL NOT TO CREATE LUNG ISSUES WITH FIBERGLASS, research safer filters if necessary!

0
Vlad Zaritsky
Vlad Zaritsky

1 year ago

Hi,
I am an engineer from Ukraine and am currently working on protection for doctors on the basis of Snorkeling mask Easybreath (Decathlon). These masks are much cheaper than full face masks 3M, and this is important in an epidemic and lack of resources.

My first mask was for a child, another company and was more like yours, but please pay attention to the connection of the air supply and air exhaust.

If the fan power is not enough, on inhalation the mask draws in air from the side channels and with this scheme it will be unfiltered. It is easy to check if you block the central channel. Perhaps the amount of air leaks depends on the fit of the bow, but is not completely excluded.

From the available filters, I found suitable ones in size and those that can be disassembled and cut into two parts: HEPA13 SC-DJ97-01670B. Looking at the technical specifications, we need exactly HEPA13, it is better than mass HEPA11. The filtering accordion has a size of (134 x 86 x 18) mm or half will be only 67 x 86 x 18.

However, doctors need a certified filters with Luer Lock, like this:
http://www.flexicare.com.ua/category/vzroslie-diha...

We are now solving two problems, how to make a compact valve so that the filter does not get wet on the exhale and how to make the filtering of the exhaled air a separate filter. There is also a problem with poor voice conduction through the mask. If the doctor is not heard, he will have to constantly strain his voice. Maybe we need to add a microphone and an amplifier.

You have an interesting idea with a fan, but unfortunately we have almost all 12V fans on sale. I even bought samples, maybe if we add electronics, we can add a step-up converter or try to use them at low voltage. Blowing with a fan makes sense if the mask does not fit snugly on the face or has other defects.

I wish you success!

0
qebehsenuef
qebehsenuef

Reply 1 year ago

You bring up some important points. The lateral channels for exhalation were plugged in the original design and the 3D printed plugs were included in the Thingiverse page. I described this but did not show a picture of the plugs in use. An updated design will be coming out this weekend. A mask that muffles the voice but does not affect your hearing with the ears outside is much better than a hood. In the hood setup where your entire head is inside hearing is difficult. Good luck with your project!