We’ve shared our experiences of how EXAIR gives each employee the chance to volunteer at an organization they feel close to for an entire workday. This is a great benefit here as we get to see where each person’s interests and passions align and it sometimes gets groups of us out to spend time together doing good for others. While I’ve already used my day for the year by judging my alma maters Senior Design Tech Expo and seeing what the next generation of engineers has to offer, today I have the joy of going even further into the future generations and showcasing some garage engineering of how airflow works.
Today, I am going to be going to a Junior High School, not just any but the one my oldest attends. My best friend and I will be volunteering for their Color Run event which is a fundraiser they put on to end the year. They take a dyed powder and throw it into the air as contestants run around a field and complete various obstacles. At one of the meetings for the event, they were discussing how they went through an excessive amount of dye powder last year. They also mentioned how it didn’t work best as they had filled squeeze bottles that you would see in a restaurant with the powder to disperse as the kids come by. Well, here in Cincinnati it gets to be rather humid this time of year, so dry powder, mixed with humid air, and compression of being squeezed to disperse resulted in lots of clumping and eventually just handfuls of dye powder being dumped on kids. It also doesn’t give the big plume that they want.
My friend and I have built a name for ourselves in the PTA as THE DADs. at the meeting, the PTA members looked at my wife who was attending, and asked if she could get THE DADs to show up for this event. Sure enough, there is no better reason to take some time off work than to douse your kid in colored powder, so we were hooked, and then the question came of, can they make this setup better. So the news came to us and we evaluated the old method. The system was simply not adapted to the scale they needed and moisture as well as the fact that some powders brick/cake when compressed wasn’t thought of. So we started brainstorming and our first thought was to take my generator and air compressor from the garage and connect a small Line Vac or even Super Air Amplifier to disperse the powder as we drop it into the entrained airflow. This setup would work, we simply don’t have the time and my generator is so loud the kids would need hearing protection. So then we looked at what we do have. I have a throw bag launcher that was constructed of an old CO2 tank and spring-loaded ball valve to get a weighted bag with a line into trees to help tie off for limb work. That is a single-shot kind of deal though, and we would be like a revolutionary war-fighter on the front line with the kids being the guerilla-like forces that don’t comply with the face-to-face combat style. So that’s out. Next, we laid out what we needed. It’s pretty simple, a large volume of air and a way to put the powder into the airflow.
Well, we both have leaf blowers, they provide a lot of air, but it is a constant flow and you can’t restrict it too much. So what can we do with a large volume of flow? Well, I happen to have a good number of PVC fittings from projects. So a good wye fitting and the leaf blower with continuous flow starts to look like a siphon-fed blow gun.
See the large volume of air will blow across the bottom of the wye fitting which will generate a low pressure on the extra leg of the wye. This gives us a draw of ambient air or in this case, an inlet port for the powder. Then the air and powder mix in the last bit of the discharge tube and voila, a plume of powder in whatever color we have on hand is created! Since I don’t have a good picture of our setup, here’s a video that helps validate our thoughts.
One of the hardest things we had to do is to account for the flow of air being constant since a leaf blower that is powered does not have a quick on-off. This is one of the main benefits of using compressed air in a scenario like this, you can quickly turn it on and off to get rapid movement of air. Blowers tend to take time to spool up, like a gas leaf blower, and they don’t do well with restriction which is why some of these ball launcher designs blow the balls back up the feed tube, restriction of the barrel diameter.
While I didn’t get to use compressed air for this, I still got to use the principles that I have learned through my years here at EXAIR, and I’ll try to tweet out some images of our color plumes when I get a chance so follow my Twitter feed as well, @EXAIR_BF.
1 – Chris Phutully from Australia, CC BY 2.0 https://creativecommons.org/licenses/by/2.0, via Wikimedia Commons
2 – Keith’s Test Garage, Airbrush Inspired Leav Blower Ball Shooter – retrieved from https://www.youtube.com/watch?v=oz1T70IjG4k