Unorthodox application for small fans

Question

Would appreciate some help for an unorthodox application of small fans. Was looking at small Delta Fans and found my way here.

The problem:

Condensation on a full, clear face shield on an ice hockey helmet due to warm air inside the shield (from breathing) and cooler air in the rink.

Plan is to use 2 small (30 mm or smaller) fans to create air flow inside the helmet with full face shield.

The shield has open vents for ventilation, some of which I covered on the inside with breathable N95 filter material (I can send photos).

Questions:

1. If the fans are placed against the breathable N95 material, will this strain the fan being directly against the N95 material?

2. Would it be better if the N95 material is repositioned on the outside of the shield, which would put the fan on the inside approx 5 mm - 6 mm away from the material?

3. What battery(ies) can power the fans?

As background, I am a 67 year old who plays regularly in a few ice hockey leagues.

One is over age 40, another over age 50 and another is all ages.

All hockey stopped in March due to Covid and restarted in June with various restrictions.

With 5 grandchildren, 3 who are under 1 years old, I did not play until this week and had to take extra precautions to mitigate the risk.

I played last weekend with the lower vents on the shield covered with breathable N95 material.

The shield is anti fog, and it didn't fog but it did build up water droplets of condensation on the inside due to my hot breathing and the colder rink air.

Same as fog, I could not see well.

My goal is to use the small fans to prevent condensation.

Greatly appreciate feedback as I am ready to buy some fans and fix this issue.

Thanks for all help.

dougw · Answer

We had a mask design contest at work, so I experimented with a design that wouldn't fog glasses up. It turns out, it isn't that hard to achieve. The design conforms to the face under the glasses and all the way up the bridge of the nose. And there is a slightly larger gap around the chin, which essentially provides a lower impedance for air flow down onto the neck than up to the glasses.

jw0752 · Answer

Hi Gary, I am very interested in what you work out. I walk everyday and here in Wisconsin in the Winter it gets cold enough so that I have to use a face covering and ski mask. The problem is I wear glasses and warm air from perspiration or a leak of exhaled air near the mask will fog the glasses or the mask shield. I have worked with pumps, pipes and all sorts of attempts to fix this problem. At this time I have a special breathing device that I have built where I inhale normally but then exhale into a tube that goes over my shoulders and out my back. I in effect have a tail pipe. In addition I have a small vacuum pump that I wear that can draw air out of the mask itself which is replaced with the very cold low humidity outside air. This system will work for me down to Zero Fahrenheit for about an hour. Winter will be here again in a couple months and I have started to try to come up with some improvements. I know what you are trying to do is different from my problem but there are enough similarities that I will share a couple things that I have learned. Adding technology to clothing and masks is cumbersome and uncomfortable. Fans consume power. You can look at the voltage and amperage rating of the fan that you hope to use. Divide the amperage rating of the fan into the Amp Hour rating of the battery you hope to use and you will have a rough idea of how long the fan will run. To work well the fan will either have to have a fresh air feed so that you are not just circulating more moist air. The other option is to heat the air or dry the air both of which have high energy costs or material costs. I can't imagine that the technology,(Fans, Wires, Batteries, Heaters, & etc) won't be more distracting than the loss of visibility. Since you are skating and moving with hockey I wonder if you could come up with some sort of air scope on the face shield that would direct air through the mask, though any filter would drastically cut the flow. It would be nice if one could find some transparent wicking material that could carry the moisture away. In your situation you probably don't have to deal with frost or ice like I do but even a layer of water on an anti fog surface can distort and mess with your sight. I will be watching what others respond and I will continue to try to come up with some suggestions. I am hoping someone on the forum has some experience and suggestions beyond what I have come up with. John

Jan Cumps · Answer

dougw wrote: ... The design conforms to the face under the glasses and all the way up the bridge of the nose. And there is a slightly larger gap around the chin, which essentially provides a lower impedance for air flow down onto the neck than up to the glasses. Yes. One of my daughters wears glasses and has made a nose-contour fitting mask for herself. No more fogged glasses, even when cycling. Another temporary trick is to wash windshield or glasses in dishwash water. Then let them dry or shake dry without wiping. The detergent film that stays behind takes care that the damp does not create a blur on the surface. The moisture is still there but is transparant. With a good formula and some practice you can get by for a few hours. When sporting you may want to repeat the exercise during half-time.

jw0752 · Answer

Hi Gary, I just got back from a walk and here is an idea. If you are going to cover the fan with N95 material and plan to pull air through the material you will need an a lot of power. I would guess the would drop by 90% or more compared to free air capacity. This is because the area of the mask material is so small. How about mounting the fan in an unobstructed hole and have it pump air out of the mask. This will produce a slight negative pressure in the mask and air will enter the mask through all the surface area of mask material that you have lining the mask. This would be a much more efficient use of the fan as there would be a lot less blockage. John

dougw · Answer

I am in a similar boat, except it is my glasses that fog up when playing hockey. My helmet face shield is a wire grid to help keep my glasses from fogging. I have tried many things over the years to combat the problem. Some work, some don't, none are perfect. I tried using fans, and they do work, but there are lots of drawbacks - size, weight, power supply, ducting, mounting, flow rates, ruggedness, etc. Our rules right now require a Covid mask be worn until the helmet has to be donned. A couple of players keep their Covid masks on during the game, but it really restricts the amount of oxygen you get. You might try a small blower instead of a fan - they generally produce higher pressure which is needed if you want to overcome the restriction of mask material. At work we make high end helmets with visors (not for hockey) and use a high tech permanent coating to eliminate fogging. This stuff works very well, way better than anything you can buy in a retail store, but is also very expensive. I wish I could afford to coat my glasses with it.

dougw · Answer

The glasses mask ... You will need a needle and thread and your choice of cloth. The design does not need straps, so you don't need any elastic. The mask is held on with sleeves for the arms of the glasses and button holes for the nose pads on the glasses. I tried to make the colors look like Ironman, but my skills as a seamstress are below rudimentary. The theme was " Even Ironman wears a mask "..... The red hoodie didn't help. Here is a rough (half-mask) template to get started, but it may need alterations for your face and more room at the chin equals less fogging .....

genebren · Answer

Gary,

This sounds like an interesting project. A lot of great insights from the comments. I have used some small fans in an art projects (PiCasso Design Challenge - Kinetic Art Mobile - Post 4 - Crash of the Death Star ) and I have quite a number of these small fans (~24mm x 24mm x 7mm @5V <30mA). If you need any for your project, they are yours for the cost of postage (same goes for anyone else that is interested in playing with these). I also have a few others (20mm x 20mm x 10mm @ 9V / 100mA).

Gene

grlassin · Answer

Doug, In April, a few rinks reopened here with restrictions and players put masks on the outside of their mask or cage. I had a cage and did that and thought it was a great way to play and mitigate the risk. I tried wearing a mask and that was not possible. After playing 4 games, they could not find enough players who'd continue to wear any covering on the ice, but they still had to in the building. I stopped then until last Sunday night. I like the blower idea but will probably start with small fans and see how that works.

genebren · Answer

Gary,

I like to use rechargeable batteries were ever possible. I would recommend Li-Ion. Although listed as 5.0V fans, these can operate from 2.5 to 5.0V, which is well within the Li-Ion voltage range (2.5V to 4.3V). The fan speed drops with the voltage, so if you need full speed across the voltage range, then maybe a boost circuit would be useful to take the Li-Ion voltage up to 5.0V. I have used boost circuits quite successfully on several of my projects (Choosing the correct Inductor for a DC-DC step-up regulator - Introduction , Choosing the correct Inductor for a DC-DC step-up regulator - Part 2 and Choosing the correct Inductor for a DC-DC step-up regulator - Part 3 ) .

Gene

grlassin · Answer

John, Bringing air in an open area defeats my purpose of trying to mitigate the risk of coming close to others with Covid still an issue. I never planned to cover the fan with N95 material and planned to place the fan on the N95 material inside the shield and the fan would draw air in through the N95 material. I can reposition the N95 material on the outside of the shield and place the fans inside, which puts them about 5 - 6 mm away from the N95 material. WOuld that provide less less resistance than if they sit directly on the material and extend battery life?

grlassin · Answer

John, I can appreciate your dilemma but am happy I am here in Houston (heat and humidity vs the cold I had back in Philly). I do better with the heat and humidity. The idea of a "snorkel" type device to channel my hot air outside the shield would work, however, even though adult ice hockey is no-check, we wear tooth guards and having something else in or near my mouth would not work. I've gotten a lot of great replies and plan to try a fan solution, though a "scoop" that channels more outside air in would help, that counters the N95 protection I added. I may look at a possible way to have my exhale channel down and out the bottom. What soft material can do that? Will post what I try and how it works. Thank you!I may

Unorthodox application for small fans

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