OPEnSampler Updates
Author: Bao Nguyen
- The OpenSampler code and hardware will be modified slightly for sewage water sampling
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Check out this quick article to see what sewage water can tell you: Coronavirus found in Paris sewage points to early warning system
Due to the serge in sampling machines, we are taking the OpenSampler for a spin and get it ready for tough manhole environment.
Deployment is planned for early next week. After the first deployment, we will redesign OpenSampler to COVID Sampler with minimal hardware for much smaller footprint.
That is Hadi, our hardware lead and Bao is behind the camera.
Author: Bao Nguyen
- McMasterCarr PE tubing seem to hold up better
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In the past, the project has been using PE tubing from HomeDepot as local and cheap source for PE tubing. However, the tubing seem to fail after some time. The tube would start to crack and eventually lead to a major system leak/failure.
Here are the picture of a crack with HomeDepot PE tubing.
To address this, we found better quality PE tubing from McMasterCarr.
| From HomeDepot |
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| From McMasterCarr |
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Author: Bao Nguyen
- Internal pressure is high when pushing water to bags
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The machine is programmed to run a demo sequence for AGU which includes FLUSH -> VACUUM -> FLUSH -> SAMPLE. However, we have noticed that during the sample sequence, some water is getting pushed to another main-valve connector tubing. We ran some crude pressure test with the setup on the right. The flush valve is disconnected and the main tube is extended to a vertical tube for water level as a pressure gauge. Running normal AGU SAMPLE sequence from valve 1 to 3, the water column was around 1m, which converts to 1.42 psi.
With high internal pressure is that water might get pushed to other main-valve connector and introduce contamination for later run. By slowing the motor down, we allow more time for water to go through the valve that connected to the target bag but will lower the overall flow-rate. To meet the EPA requirement for attaining representative samples of suspended sediments, the required flow-rate for this 11/64" ID tubing is 550+ mL/min [Link]. More testing will be done to determine if slowing the motor down is a viable option.
Author: Bao Nguyen
- New bag connection design and mechanical support
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Check out our new design for the bag. User can now quickly swap the bag with only one pull and one push.The lock is 3D printed and the push-to-connect is off the shelf just like the bag cap.
More information of the update can be found on eDNA Update
Author: Bao Nguyen
- Testing new voltage regulator for Logic Module
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The previous voltage regulator was a bit bulky and overpower. The LM2575Sx-5.0 was rated for 1A continuous, but provide less than 78% efficiency at 100mA normal draw from the Feather. The old design also use large inductor, as well as capacitors that increase the total height of the system.
More information of the update can be found on eDNA Update
Author: Bao Nguyen
- OPEnSampler get re-modeled based on the eDNA electronic and hydraulic
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Here is a sneak peak of the new design. Hadi has been working hard on the project and we have made great design chances in comparison to the previous version.
More update will be posted later!!!
Thank you Mitch Nelke, for setting the ground work for the machine. He was the first hardware developer for the previous versions of the OPEnSampler before the OPEnSlab decided to migrate to GitHub.