Darren Lewis

It's easier to code VCV mode, you just need to set the motor speed based on the target flow rate needed to acheive the target tidal volume (integrate flow to get volume, I've done this in the getFlowRate() function). I have uploaded my old VCV code that you can use as a starting point: https://github.com/Open-Vent-Bristol/Open-Vent-Bristol_MCU/tree/develop/Archive%20V2.0%20rig%20code/OpenVent_Bristol_rig_V2.0_VCV_V3

Have you installed the library for the motor shield?

A hair dryer might work too, you will have to be careful about spreading the heat evenly like @montyyx89 said. Another alternative is you could make a handle on the aluminium frame so you can hold onto it outside the grill (like a frying pan handle sort of thing)

Yes that works great as well. Yeah the industrial machines remove the heat source roughly at the same time as the plastic goes over the mold I think. Since I posted this I tried placeing the 3D print in the freezer first, and the results were even better.

To be honest I'm not sure exactly, it was designed by another guy in our team using CFD simulations. But also the calibration equation in the spreadsheet is based on those dimensions

Apologies I should have said in the post but you will need to download and install the Arduino motor shield rev3 library. https://github.com/gallingern/arduino-motor-shield-r3

Yes you’re right, all of their paper work is needed to help prove that the device will be safe. I think that was MedTech?

Agreed it’s not an easy task but we’re working on it

Yes you’re totally right, we are now using a separate inhalation and exhalation circuit with PEEP valve on the exhalation. That should solve the CO2 problem.

Hi, yes you can use MPX5010DP for the pressure sensor as well as flow rate, just leave one of the connection pipes disconnected to allow pressure measurement relative to ambient. Differential pressure sensors (DP) have 2 pipes to allow you to measure the difference in pressure between 2 points in your circuit, gauge pressure sensors (GP) have 1 pipe because they are only designed to measure pressure relative to ambient. Hope that helps. I won't post any contact details publicly here but you can contact me via my email which you can find on the website: https://openventbristol.co.uk/

Unfortunately I would suggest not using MPX4250DP as it has much courser resolution than the MPX5010DP. For each ADC 'tick' of the MPX5010DP the pressure would change by about 10Pa but the MPX4250DP would need a change of about 244Pa. I don't think this would give fine enough control for the motor PID loop. Sorry

Hi thanks for your message. I totally agree, this should be used with a viral filter, hospitals should have a good stock of these. In my video you should see that I was using one. Also the MHRA requirements request that the device is compatible with one.

please see my latest imporved design here which is closer to meeting the MHRA requirements: https://www.instructables.com/OpenVent-Bristol-V20-COVID-19-Rapid-Manufacture-Ve/

Yes I have, please see my latest imporved design here which is closer to meeting the MHRA requirements: https://www.instructables.com/OpenVent-Bristol-V20-COVID-19-Rapid-Manufacture-Ve/

Hi all, please see my latest imporved design here which is closer to meeting the MHRA requirements: https://www.instructables.com/OpenVent-Bristol-V20-COVID-19-Rapid-Manufacture-Ve/

Hi thanks for you message, my latest design publications should answer most of your questions.This design gets us closer to meeting the MHRA requirements. The Pressure, I/E, volume and frequency are restricted to what we believe to be safe maximums but if you replicated my prototype it should be straight forward to extend these if you wished although some combinations of those settings may not be possible due to physicals restrictions https://www.instructables.com/OpenVent-Bristol-V20-COVID-19-Rapid-Manufacture-Ve/I'm very grateful for your post on your website, but would it be possible to update to update it with my latest design for me please?It runs PVC, PVRC is possible with a small software change, I think BIPAP/assistive mode may be possible as well but I haven't tried this yet.It …

Hi thanks for you message, my latest design publications should answer most of your questions.This design gets us closer to meeting the MHRA requirements. The Pressure, I/E, volume and frequency are restricted to what we believe to be safe maximums but if you replicated my prototype it should be straight forward to extend these if you wished although some combinations of those settings may not be possible due to physicals restrictions https://www.instructables.com/OpenVent-Bristol-V20-COVID-19-Rapid-Manufacture-Ve/I'm very grateful for your post on your website, but would it be possible to update to update it with my latest design for me please?It runs PVC, PVRC is possible with a small software change, I think BIPAP/assistive mode may be possible as well but I haven't tried this yet.It has run for at least 12hrs during testing without problems. I haven't been able to life test it more than this unfortunately.

Hi, if I’ve translated your French correctly, I am currently working on these and will share on instructables once completed. Thanks Darren

Hi Josh,Thanks for your message. The error you have is probably because you don’t have the motor driver library installed, apologies I missed this out of the guide. Here’s a link to it: https://github.com/gallingern/arduino-motor-shield-r3My next version will use the Velleman LCD button shield. I’m hoping to get this version completed soon and once I do I will upload the code and everything to Instructables.Thanks,Darren

Thanks EWB, had a quick look on your GitHub list but I couldn’t see my design

Hi Jude! Thanks for the comment. Is that "OxVent"? Their design looks nice and simple with few moving parts, although requires a good seal and I guess an air line? We might want some electrically powered devices in use as well to avoid overloading hospital air lines. I thought the BVMs don't do constant pressure (CPAP)?

Also wondering if you have found a solution to how the BVMs can't hold inspiratory pressure?