On Tue, Apr 14, 2020 at 03:44 PM, Erich Schulz wrote:

Could be useful for rapid prototyping.

Yes, that is probably where they would fit into the scheme of things. But lifecycle testing would provide data. And for third world builders it provides an option.?

They are meant to be inserted in the narrow around 1/8 inch tubing that activates the exhalation valve, not the patient air circuit. Testing them with a "calibrated" mouth test fixture showed very little flow restriction. Should work for the pneumatic valve activation circuit.?

Tom, wb6b

On Tue, Apr 14, 2020 at 07:10 AM, Marcelo Varanda wrote:

different diameter will need different coefficients in order to get same result.

Hi, Here is the information Dr. Schmidt created on orifice disc meter flow sensors.?

Tom, wb6b

Hi,?

I was thinking of using a check valve to pressurize my Toro jar-top exhalation valve. The idea is to not need an extra solenoid valve to get the dwell time.

The pressure to close the valve would be supplied through a check valve, then the valve could stay closed after the closing air pressure stops. After a dwell delay the solenoid, already on the modified sprinkler valve, could be activated to release the pressure and open the exhalation path.

In looking for ways to construct a one way check valve, I realized I had a reasonable supply of one valves already sitting around the house, in the humble hand soap pump dispensers.?

Tom wb6b

-----------

-----------

-----------

OK,? want to give everyone somewhat of an update.
The team at UF is "huddling" now and may be less accessible as they work with a private vounteer to get ONE VERSION through the FDA, named the "PanVent"? (pandemic ventilator).? ?Once that is done, a huge amount of new informaiton may show up on their web page, but for now, they are becoming monks.

Airway Hardware:? ?settled on the lawn sprinkler inspiratory, and modified lawn sprinkler Expiratory (Yeah!? Marc Allen!!!!)

Electronics Hardware :? I have a so-so physical build that probably most of you have seen by now and now we have a group of student AND physics departement staff working to build one that might be more well received by a "government agency".? ? ?Mine works, but the construction is.....welll....a bit flimsy

Software:? We have at least three teams working on this.? ?Despite a computer freeze and complete loss of 2 hours work I now have a BARE BONES working ventilator that has four different alarm limits (high and low on presusre and flow) and displays most of those and WORKS.? ? That design is being reviewed and hopefully improved by Team Purdum/Farhan.? ?Meanwhile, we have Team Graavenstein having reviewed Marcello Code and trying to document, and also pursuing their own code designed to be readable by simple-minds like me.? ?And we have Team Varanda stuck still not with a BMP280 but we ahve other volunteers working on his code (and I think creating branches? on github?) --- in hopes of assisting him.? ?If we get more than one team across the finish line that is fantastic!!!? ?Team Varanda has by far the best user interface but the code just isn't finished.? ?Team effort here guys!!!

MANUFCTURERS:? are now contacting the office of technology licensing at UF and I understand they are doing a brisk business sighing university and/or manufacturers up to become part of the dispersal prcess.? ?use your google fu and contact THEM to get on with that.

VOLUNTEERS:? Finally I have FOUR people working to improve on my hardware building skills.

We can't forget. Dr. Stapleton who is turning out one to two FINISHED ASSEMBLED boards per day,a nd Dr. Gibson who did our first prototype board in record time.

We now have THIRTY base boards (Ashhar 1.0) and TWENTY of my crappy power supply/transducer boards in hand....and none are assembled save one.? ?

Huge huge huge effort is now being put on the FDA application and of course those documents will have us change and/or improve both hardware and software -- but there is a bit of a "tight lips" on that until we get it submitted, so I cannot give exquisite details.? ?Hopefully this will be DONE in a matter of days and then there will be an EUA (cross fingers!!!!) and you guys can go wild building and/or improving these things, based on the base EUA design

Thanks to ALL of you who have contributed so much, so fast.? ?You would not believe how important amateur radio operators have been, and are, to this project -- the electronics shop at Physics?? ?Its another ham running that who is heading up the building.? ?You hams rock!!!


Gordon KX4Z

A team of one electrical engineer and one materials scientist + mech engineer in Dortmund, Germany.

We are working on a system that does pretty much everything a modern ventilator does, CMV, IMV, CSV in Pressure and Volume control modes.
The biggest tasks that remain to be solved:
*installing the flow sensor and having true volume control
*adding an alarm
*putting the whole thing in a cool box
*a million more things probably

Please comment on what you think has the greatest pareto improvement potential!

Here's my latest video plus you can find earlier ones on the same channel.



Awesome resource, thanks Erich:
A great checklist for us ventimakers:

Thanks. Once I get the system (still with FedEx) I will play with it and I may better to understand the numbers I will be getting.

I am not talking about a "dynamic" calibration (a zero reference for ambient pressure)

But a "calibration" about the physic aspects where the sensor is located.

For example:
? if the sensor is located in a wider pipe then its Tidal Volume would be greater for a same given pressure than when installed in a narrower pipe.

Sorry yes that her.

thanks

Thanks Dave, but the other questions still stand:

What method do you recommend to establish a baseline to calculate the coefficients ? I guess a same controller monitoring sensors in pipers with different diameter will need different coefficients in order to get same result.

Gordon, when you have time can you send me her contact info.

thanks

Phil M

开云体育

please refer to engineering specifications document V1.6 posted here, it describes the alarm conditions.

?

Cheers,

Dave

Hi Erich, now about Tidal Volume,

What is the unit used for it in ventilators and what kind of alarm it would require?
What method do you recommend to establish a baseline to calculate the coefficients ? I guess a same controller monitoring sensors in pipers with different diameter will need different coefficients in order to get same result.

Thanks

Thanks a lot Erich,

MV

Since the last report the passive valves were updated to use steel coil springs. The pressure range and and cycle to cycle consistency are much improved.
The Rainbirds have accumulated 1,278,000 cycles.

An updated report is attached.