Our project was designing a way to circulate water around a vest to be used as a cooling system for people to wear. The system uses HDPE plastic with channels sealed into it for water to pump through to achieve the circulation of water effectively, additionally we used a quick disconnect system to make it easier to move and interact with, and a Y splitter to adjust flow.
After a certain amount of time firefighters must break from the fire, and do something called rehab. This process is intended to bring the firefighters' vitals back down and around a safe range so that they may return to the fire. One way they do this is using wet rags on their neck to cool them down, so we sought to improve on this by implementing our vest, keeping them dry as well as more quickly cooling them.
We began with considering ways we would be able to cool someone down. And it stuck out to me that in the hospital they use a blanket which circulates cool water to reduce a fever patient's temperature. We also considered that cool air could also be used, but thought that it may not be a reasonable option when actually on the scene of a fire. From there we decided circulating water would likely be the better option considering they already bring coolers with them to calls. We began with testing ways that we could actually accomplish this, so we tested just wrapping someone in tubing and hooking it up to the faucet. Doing that we were able to see that it would be effective, but that we should try and maximize the contact surface area between the person and the tubing. Knowing this, and that the medical industry uses blankets I thought we could try and create our own version of the blanket that could be worn, and so we started off creating a cooling back with a food sealer and the plastic it normally uses. Doing this we were able to tell that we could create our own version of them, so we did some research into what plastic bags are normally made of and if we could find sturdier or thicker versions. After that research we ended up with 6mil HDPE plastic sheet that we could seal and shape into the cooling packs we needed for the vest. Additionally I worked on the quick disconnect system which involved finding fittings that worked with 3/8” ID tubing and then modeling them in SolidWorks. After I modeled them I was able to create two blocks that were negatives of the male and female connectors. This allowed me to create a housing that combines two quick disconnects to make it easier to connect and disconnect the vest from the pump. I designed the blocks so that one of each disconnect’s two releases had been preloaded/pressed so that a lever could be mounted above the other release of each one and actuated at the same time.
Left: The exploded view of the quick disconnecto block design.
Right: The 3D printed version of those quick disconnect blocks
Left: The release lever and the insert that interface with the releases.
Right: An individual cooling pack with channels sealed into it
For testing we started off basic, showing that a person will feel the cool water circulating. From there we worked on finding a flow rate which would e effective for replacing the water as it warmed up as well as did not burst the cooling packs we made. And then finally we did a test which measures the input and output liquid temperature so that we could see a meaningful representation of the water removing heat from a person.
Throughout this project we came to learn how much fine tuning systems that manufacture plastic to plastic joined part require. We also experienced quite a few times how the dimensional tolerance of parts can varry while 3D printing, as well as how a 3D printed part can both feel and be fairly sturdy but still not be strong enough when subject to forces that separate they layers of the print.
HDPE Plastic Film
Two 3/8" Male Female Quick Disconnect Pairs
3/8" Vinyl Tubing
A ~3000 GPH Sump Pump
High-Vis Vest