Obturator manufacture for a respirator

How to make any, even the simplest, one-time respirator better, get rid of air leaks when inhaling along the edges of the mask and reduce pressure on the face, especially in the nose, without spending a lot of time and money.

Due to the fact that at the moment, a number of specialists express their fears about the possibility of developing a global pandemic 1 , 2 , 3 . And having information from studies 1 , 2 , 3that disposable half masks with the NR index and reusable half masks with the R index often have problems with air leaking around the edges of the mask at the time of inhalation, and, unlike reusable half masks with replaceable filters and a silicone seal, they are not able to fully check the tightness lodging. I decided to check the possibility of self-production by simple means, from affordable, inexpensive materials, a seal for masks. Its presence improves fit and reduces the likelihood of air leaks.

Masks originally produced with a shutter are not always readily available and can cost more than analogues without a shutter. The ability to independently produce a shutter seems to be a pretty attractive alternative, buying a mask with a shutter. Of course, silicone half masks look the most preferable option, they have great potential for creating a tight fit on the face, and allow you to perform a better leak test by the user. But they are not always possible, or convenient to use, for various reasons. In the future, we will talk about disposable respirators with an index of R or NR for simplicity, I will write just a mask.

I began by trying to identify the material encountered as an obturator. Of all the shutter options available on the market, I decided to dwell on one in my opinion the most suitable for the task. A study of the catalogs and photographs of the obturators on hand by the chat participants in the telegram channel showed that PVC is used for the UVEX 2310 obturator based on its data sheet . The search for suitable material led to the discovery of EVA ( ethylene vinyl acetate) Wikipedia says that the material is quite safe for humans, I decided to use it, due to the availability of material on sale. It can be found, for example, under the brand name foamiran, also sold under other names. Where I purchased the material, it was available in sheets of various sizes from 20x30 to 60x70 and a thickness of 0.8 mm to 2 mm. Perhaps there are other thicknesses and sizes. This material is also sold in sewing and needlework stores, where it is available in packs of 10 sheets of 20x30 1 mm thick, there are probably other packaging options on the market, but they haven’t come across to me. I used 1 mm and 2 mm material. This thickness in my opinion is most suitable for this task. Those masks that I saw, factory-made, with a similar implementation of the obturator, have a thickness of the obturator material close to 1 mm.The material may have a different texture, but it is present only on the one hand, I did not find two-sided texturing, but we do not need it.

Examples of textures. The lowest silk, medium terry, the top without texture. Without texture, the material is more plastic and easier to stretch, after the experiments, I settled on it.




All 3 material is large. Silk.



Terry



Without texture



I used 2 different masks. The first mask is JM6626.



The second is Julia-319.



The JM6626 had a similar obturator, but I was not happy with the fact that it was pressed in and did not work as I expected. The sealer is soldered around the perimeter, which does not allow to realize the full potential of the possibilities to combat air leaks when inhaling.

For the manufacture of a shutter, in addition to the foam itself, we need a pen or marker, a sharp knife or a scalpel, a ruler, double-sided tape on a foam basis, ideally 5 mm but 10 mm is also possible. I think it’s possible to use a glue gun or glue for gluing the shutter, the main thing is that the glue composition retains volume and high plasticity throughout the life of the respirator. But I did not check these methods and worked with adhesive tape.
I already had a suitable 10 mm adhesive tape.



Pretty old but quite alive.



So I used it in the middle. It is quite simple to dissolve the adhesive tape if you glue one end of it to the edge of the table, and hold the other end in your hand while maintaining tension. According to the experience of pasting two masks from different manufacturers, 240 mm will be long enough for scotch tape, but you can measure the perimeter by which you will glue the scotch tape with a thread and get your own, more accurate length, I recommend adding a couple of centimeters to it to secure.
So the tape is prepared, a sheet of foam on the table. As a backing I used a cutting mat, you can also use a kitchen board or plywood. For your convenience, if you have a large sheet, you can cut off part of it, as I did.
I recommend using a pen rather than a marker, as the pen does not stain the edge of the respirator.
We apply the respirator to the side that is less attractive to you, this side will be glued to the respirator.



Gently circle a bunch of contours.



It should be something like that. we check that everything is smooth and the outline is clearly visible everywhere.



Carefully cut out.



It should be something like this.



Next, we need to cut the inner hole under the mouth and nose. I have a distance from the lower edge of the lower lip to the middle of the nose bridge 7 cm. If I retreat 3 cm from the edge, I get a comfortable neckline (I experimented with different shapes, everything turned out to be quite individual and depends on facial features).
Below will be 2 examples of how to cut out the inside, but the markup will be the same 3 cm from the edge around the entire perimeter.

The first variant is the shape of the internal cutout.



The result of the markup.



One of the options for connecting markup points.



Now you need a knife or a scalpel.



I used a scalpel. Carefully cut along the contour.



In the end, it should turn out like this.



Degrease with alcohol. We glue the tape around the perimeter, pay attention to ensure that he does not go beyond the edge of the mask.



Carefully cut the tape for the perfect fit. The end should not creep into the beginning, nor should there be a gap. I try to do a bit with a margin, literally a couple of tenths, and then stack so that the edges rest against each other.



It should be something like this. Before the final pressing, we turn the edges so that they are parallel to each other.



Remove the protective layer.



Everything is almost done, sticky. We place the shutter up on the side on which the markings were made. Degrease with alcohol. Since the material of the shutter is very plastic and if you put it on the mask, in addition to the need to somehow fix the mask, you will also have to control that the shutter bending under its own weight does not stick at arbitrary points. I tried this way I don’t like it, because of less control at the time of gluing.



Gently touch the edge of the nose, trying to control the symmetry from above.



If necessary, make adjustments. When the shutter rests as it suits you, we squeeze your fingers along the edge so that our double-sided tape clings better.



Result. The view from the front side.



Do the same with the second respirator.



The second option is the shape of the internal cutout.

This neckline may be better suited to people with high nose bridge. Try it, see what is best for you.



Vertical size.



Please note our shutter does not lie flat on the mask, but after dressing it stretches and begins to conform to the shape of our face. That provides better protection against air leaks when inhaling.



Another view



An example of how this works.



In my experience, while wearing, even if the mask becomes wet, the shutter does not peel off and is not saturated with moisture. No problems during operation were noticed.

But still, I highly recommend taking one mask and walking in it in a safe place, to make sure that in your case everything went well and there are no problems with wearing it. You can also try to breathe in the mask for about 5 minutes, and then, when it is warmed up by your breath, open the refrigerator or go outside if it is cool outside and take a few deep breaths, if there is an air leak you will feel it due to the chill, ran through the face, at the site of suction.

I also note that some manufacturers, taking care of user convenience, flash the edge of the elastic band, folding it in two, which does not allow the rubber band to slip out of the mount when loosening it to remove the mask.



If the manufacturer did not take care of this in your respirator in advance, you can correct this point using the same double-sided tape. Cut a narrow strip, in my case 5x10 mm, and glue it on the side of the gum that looks to the head when the mask is on, and you tighten the gum.



Remove the protective layer, gently fold the gum and squeeze it with your fingers. In the end, it should turn out like this.



During testing, it turned out that on some individuals, some respirator models may experience stresses that could potentially lead to the separation of adhesive tape from the respirator. If you encounter such a problem or want to play it safe, you can use a stapler to strengthen the structure.



Also, as an experiment, I put together a sandwich made of thick and thin foamiran. My thin 1 mm foamiran has a more pleasant to the touch structure. In such a sandwich, the lower 2 mm material acts as support for the upper. And the upper one, due to its thickness, has the ability to more accurately repeat all the contours of the face. The experiment paid off and I managed to achieve excellent comfort and completely exclude air leaks when inhaling in the nose bridge region. For a perfect fit, I made small 5 mm cuts. They allowed the material, or rather to repeat the contours of my face.



Search for an ideal respirator that could be used repeatedly or repeatedly in the event of a pandemic and disappearance from the sale of PPE. led me to this model. It exists in three versions P1, P2, P3. For my experiments I purchased P2. In my opinion, the big plus of this model is the fixation device, but about it a little later.



This respirator has a hard plastic frame, which allows you to not touch the soft material of the mask when dressing and removing, but eliminates the use of a stapler. A narrow board requires an adhesive material with a higher fixability.



On the advice of the sellers, I decided to try this kind of tape.



As I was assured in the store, it is the tape in the blister that will have the strongest grip. as there is a similar tape but not in the blister.



I used 2 mm foamiran as the first layer.



Then, putting the respirator to his face and clasping it with his palms, pressed it, this formed the main contour of the face.



Since the 2 mm material is quite elastic, I slightly modified the outline with my hands, gently stretching the most stretched sections.



Also, I had a desire to test the possibility of using the mesh as a fixative for the nose clip. This one.



Having experimented with its form, I settled on this one. For clamping, I used steel wire with a diameter of about 1 mm in diameter.



The grid is separated from the material and is quite dense and elastic.



Closer to the edge smoothly passes into the body.



Respirator with fitted nose clip. It is easily put and removed, without extension, and I believe it can serve for quite some time. The respirator is also not damaged as it is installed or removed. Any tool for this is not required.



The clamp slightly compresses the filter material, I needed this particular effect.



In conclusion, I pasted a second, thin 0.8 mm thick obturator. For him, I used 10 mm scotch tape, which I wrote about at the beginning, without dissolving it.



The thickness of all layers was about 5 mm.



It is clearly seen that the thick foamiran remains elastic, while the thin stretches and stretches better and repeats all the bends of the face.



Having gained experience in using different respirators, I came to the conclusion that for quick putting on and taking off, the most convenient design is with a sliding elastic band, and such a latch on it. If you need to wear a respirator quickly, not in the most convenient conditions and not for long, this is probably the best option for fastening. But of course, 4 tightening elastic bands allow you to create more pressure.



And in the end I give an image of respirators for which I was not able to make an obturator using double-sided adhesive tape.



The problem is that the data respirator is very soft and it has almost no flat board. This makes it difficult to use both adhesive tape and a stapler.



I hope my experience will be useful to you and you will use it to improve the fit of your masks.

I also want to express my gratitude steanlabfor supporting and motivating me to write this guide.

This is my first publication on Habré, I hope that I managed to do everything correctly and you were comfortable and pleasant to get acquainted with this guide.