Re: alternative inspiratory valve
many thanks - I'll try to get the engineering student to ponder the design and see what they come up with. Erich Schulz,?mbbs, mba, fanzca 0410 277 408
On Tue, 14 Apr 2020 at 09:30, MA < wa9zco@...> wrote: Your Welcome Erich,
Yes you can use my photo.
Yes & No, the existing 24vac solenoid needs to remain in place to plug the hole but is not used.? There is a small press fit stainless steel tube in the center that must be removed.? This is the existing valve pilot supply which is no longer needed.? The hole that the tube comes out from needs to get plugged and I used a #6-32x1/4" screw.? Another screw needs to be put into the center of the movable spool to plug that hole also.? Next the spring needs to be moved from the top of the valve spool to the bottom so it pushes the valve spool to the open position.? The valve will work with the spring in the position but it would work longer if there is a small plastic part inserted to balance the spring base so it operates in more of a straight position.? The Orbit valve will not be a normally open valve requiring pressure to close the valve.? The valve does not require much pressure to close the valve.? My test required about 4psi.? Next thing is to remove the valve drain plug and insert a small plastic flexible tube that will be used to pressure pilot the valve to the closed position.? A remote external pneumatic valve is required to pilot operate the Orbit valve.? The remote pneumatic valve should be a three way valve using the normally open position to keep the Orbit valve closed until the pneumatic pilot valve is operated.? The coil on the pilot pneumatic valve should be 12vdc.? The unused port of the pneumatic pilot valve should remain open to vent pressure from the Orbit valve.? The pneumatic supply pressure should come from the inlet side of the inhalation valve.? I ordered a pneumatic valve but it is not hear yet so cannot send a picture. ?
Enclosed is a link to the pneumatic valve I ordered:
Please let me know if you have any questions.
Marc Alan
WA9ZCO
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Focus on pressure sensor unit, alarm and display
I first integrated a pressure sensor based on NXP 7002.
Its analog values, once read from ADC,? ranges from 0 to 613 (integer number).
Someone provided a formula where those values are translated to -3.57 to 41.08 BANANAS.
I mean BANANAS because one individual calls it cmH2O and a seconds InchH2O.
Anyways... once I implemented the integration nobody questioned the values being displayed nor the alarm thresholds hardcoded to 4 for low and 35 for high BANANAS.
Now we are up to replace NXP 7002 for pressure to a BMX280. In a normal world we KEEP THE SAME UNITIES. So my logical approach is to keep? the very same -3.57 to 41.08 BANANAS range regardless the sensor we are using for PRESSURE (I am not talking about Flow sensor).
Therefore, if there is any objection please step in and clarify.
Thanks,
MV
which provides voltages that transpates to integer values
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Hi Tom,
You are correct, the internals of the Toro valve looks very similar to the Orbit valve. ?Do not need the anti-siphon valve so hopefully that can be removed. ?I do not have one of these valves otherwise I would try the modification. ?I would recommend that you try the modification and try the valve. ?Please let me know if you have any questions.
Marc Alan
WA9ZCO
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Re: alternative inspiratory valve
Your Welcome Erich,
Yes you can use my photo.
Yes & No, the existing 24vac solenoid needs to remain in place to plug the hole but is not used. ?There is a small press fit stainless steel tube in the center that must be removed. ?This is the existing valve pilot supply which is no longer needed. ?The hole that the tube comes out from needs to get plugged and I used a #6-32x1/4" screw. ?Another screw needs to be put into the center of the movable spool to plug that hole also. ?Next the spring needs to be moved from the top of the valve spool to the bottom so it pushes the valve spool to the open position. ?The valve will work with the spring in the position but it would work longer if there is a small plastic part inserted to balance the spring base so it operates in more of a straight position. ?The Orbit valve will not be a normally open valve requiring pressure to close the valve. ?The valve does not require much pressure to close the valve. ?My test required about 4psi. ?Next thing is to remove the valve drain plug and insert a small plastic flexible tube that will be used to pressure pilot the valve to the closed position. ?A remote external pneumatic valve is required to pilot operate the Orbit valve. ?The remote pneumatic valve should be a three way valve using the normally open position to keep the Orbit valve closed until the pneumatic pilot valve is operated. ?The coil on the pilot pneumatic valve should be 12vdc. ?The unused port of the pneumatic pilot valve should remain open to vent pressure from the Orbit valve. ?The pneumatic supply pressure should come from the inlet side of the inhalation valve. ?I ordered a pneumatic valve but it is not hear yet so cannot send a picture. ?
Enclosed is a link to the pneumatic valve I ordered:
Please let me know if you have any questions.
Marc Alan
WA9ZCO
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On Fri, Apr 3, 2020 at 10:13 AM, MA wrote:
I have an Orbit irrigation valve and yes it has this problem so I modified my valve for remote pilot operation. ?This solves the back pressure problem and now it has virtually no back pressure issues. ?
Hi, I opened the Toro model 53763 valve up and the construction looks similar to the Orbit "jar-top" valve. Possibility it (or a model without the extra "anti siphon" valve) would be an additional source for valves that could be modified to work as an exhalation valve. Tom, wb6b ------  ------
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alternative inspiratory valve
Thanks MA!
is it ok if include your photo from 1102 in my briefing doc?
This is essentially just taking a solenoid based valve and replacing the solenoid with a pneumatic line, right? or am?I missing something?
e
Erich Schulz,?mbbs, mba, fanzca 0410 277 408
On Tue, 14 Apr 2020 at 01:50, MA < wa9zco@...> wrote: Erich,
Details of my modified Orbit valve can be found in the post 1102, 1108, 1111 and 1113.
Please let me know if you have any questions.
Marc Alan
WA9ZCO
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I can't figure out Marcelo's code at the moment and we have a team in Montreal hoping to look at it tonight.? ?Perhaps Marcelo can make it do what we need -- the user interface is very nice, but not achieving the design goals will not work.
I now have Ashhar's code displaying peak inspiratory pressure, low and high alarms work, the watchdog works, and I have temperoriy disabled the I2C lockout until I can make a front panel "recovery" of that.? ?But otherwise it is WORKING and I have also (for demo purposes) hard coded in a very simple inspiratory pause (you'll see it if you search for MOTOR and see that I delayed opening the expriatory valve until cut_off +4 slices.... inestead of cut_off.? ?This is quite exaggerated but it allows people to SEE it.? ?
If you can add ADJUSTMENT OF THE HIGH PRESSURE ALARM and get that displayed in the lower left screen -- I have a 35 permanently showing there --
and add display of the tidal volume and FIXED tidal volume alarm? (300cc,? 1000 cc will work for now) --- that would be good enough for the FDA demo tomorrow.
Thanks folks!? See you in 3 hours.
Gordon
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I used zip ties in my design and it actually failed at 468k cycles tiny hole at the head of the zip tie from abrasion during inflation.
In their lastest design (link below) they do have CA glue and fishing line holding it in place.? They published this after I started my test.? I may iterate to that design and continue my test to see the next failure mode. Everything else looked great. Not as clean as a restarted test but I don't think we have the time to restart before UF team has to decide what direction to go.?
https://simulation.health.ufl.edu/technology-development/open-source-ventilator-project/build-test-instructions/
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Hi, some LatinAmerican approval agency, like the ABNT (Brasilian) put some standards related to medical equipment (ISO/IEC) to the public in a effort to help in this time.
Plus Here my googling related to mechanical ventilator standards?
(some of the ISO/IEC related documents are in portugues).?
Attached the screenshot of the folder with the description of the files.
original Link of the ABNT Standards:
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Re: Help with Tidal Volume
Now let me explain how Ashhar made that time measurement work out properly.? ?The following code is at the very beginning of vent_slice() which is called over and over and over....but does nothing until it hits the end of? a defined slice of time (hence the name) because of THIS little bit of code right at the start:
now = millis();? ? //? ?read the current time?
? if (next_slice > now){
? ? //? Serial.print(".");
? ? //? With MAX_PHASES (number of slices to a ventilatory cycle) at 20, system printed 8 dots at resp rate of 28?
? ? //? With MAX_PHASES (number of slices to a ventilatory cycle at 60....? did not print any dots MA -- unable to keep up.
? ? //? So the maximum MAX_PHASES isn't that much....
? ? ? ? return;? ?//? it RETURNS if we aren't yet to, or beyond the exact "tick" of the millisecond timer that we're wating for? ?
? ? }
? ??// Note that it may go through many times before it ever goes any further.
......and all the ventilatory caluclations are THEN done after each of 20 time slices (all about the same number of milliseconds) in the respiratory cycle.
I measured the adequacy of this and found that it had enough time LEFT OVER to print 8 dots on the serial port at 9600 baud at a respiratory rate of 28 with 20 slices per respiratory cycle -- but when raised to 60 breaths per minute it no longer had any time left over --- so it has plenty of time at 28 breaths per minute for 20 slices.?
and that is before optimizations that might occur if WE EVER GET THIS SOFTWARE ACTUALLY wORKING.
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Re: Help with Tidal Volume
On Mon, Apr 13, 2020 at 09:02 AM, Marcelo Varanda wrote:
exLitersPerCycle = exLitersPerCycle? +?? (? CalculateInstantFlow() * 60 / ( (float) (beats_per_minute +MAX_PHASES))? )? ;
This is pretty simple. But you caught an ERROR in the above line of code.? ? The code should MULTIPLY beats_per_minute? times MAX_PHASES, not add them!!!!!? ?I'll correct that!!!!! One respiratory cycle is 60 seconds divided by the number of breaths per minute.? ? So, respiratory rate = 10,? respiratory cycle = 6 seconds. Divide the entire cycle (6 seconds) into MAX_PHASES slices (in this case, 20).? ?Then each time-slide is 6/20 = 300 milliseconds. So if you take the instantaneous flow rate and multiply it by the time of one slide? (60 / (breathsperminute *? number of slices) )? you get the milliliters of air in that last 300 milliseonds? (or whatever the slice is) Then you keep accumulating those through ONE EXPIRATION. Because the code checks the time and only makes the calculations JUST AFTER the 300 millisecond timer has elapsed, it is fairly accurate. Make sense now??? Thanks for catching the erroneous +? where there should have been a * Gordon Now....we need an ENGLISH EXPLaNAtion of the timing loop of the Marcelo code, please? Gordon
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Re: Help with Tidal Volume
Marcello, One of the side effects of "big loop" code programming is the non-deterministic order of function execution. Timing calculations?cannot rely on the number of cycles that the loop or for that matter, any function within the loop, is executed. In the absence of RTOS, the best way to resolve this issue is to have a hardware timer with an attached ISR advancing a software counter upon each interrupt. This counter value then becomes the time-base reference for the rest of the code. It is best to use an "unsigned long" or even "unsigned long long" variable for the time base counter. Setting the hardware timer to produce an interrupt once every 1 mSec is a good starting point.
--Ron N7FTZ
On Mon, Apr 13, 2020 at 9:02 AM Marcelo Varanda via <mv_email= [email protected]> wrote: Dear Sirs,
First a disclaimer: a have zero background about Tidal Volume. I only imagine that it estimates air volume based in a factor of the pressure accumulated in the time domain.
If my assumption is correct than I believe that the sample code I have received to calculate Tidal Volume is incorrect/incompleted.
It has been called with no pre-defined time as the function has been called from the main loop.
The main loop timing, for the POC sample code, may change as features are added/removed as well as CPU load changes per loop duo different operations (buttons/LCD updates etc).
I do not see any compensation based on elapse time. Here is the actual code:
exLitersPerCycle = exLitersPerCycle? +?? (? CalculateInstantFlow() * 60 / ( (float) (beats_per_minute +MAX_PHASES))? )? ;
?where:
?? CalculateInstantFlow(): returns a relative pressure (from pressure calibrated reference)
?? beats_per_minute: we can consider "constant" if operator does not change it
?? MAX_PHASES: constant
It may work if it is called from a known periodic time or multiplies by an elapse factor.
But even so I would guess that it is missing a coefficient tied to the pipes and other characteristics.
I would imagine that wider pipes vs narrow pipes with same reading pressure would have different tidal volumes as wider pipes would "deliver" more volume per milliseconds
If all that is correct then I assume that we need method to find this coefficient.
Thoughts?
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I seemed to recall a brief discussion about using PEX copper crimp rings instead of zip-ties or nylon thread (sorry, can't locate the original post). Did this idea go anywhere, or has the seal on the butyl tube converged to multiple wraps of nylon thread and CA or industrial zip-ties?
Cheers,
Christopher
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Dear Sirs,
First a disclaimer: a have zero background about Tidal Volume. I only imagine that it estimates air volume based in a factor of the pressure accumulated in the time domain.
If my assumption is correct than I believe that the sample code I have received to calculate Tidal Volume is incorrect/incompleted.
It has been called with no pre-defined time as the function has been called from the main loop.
The main loop timing, for the POC sample code, may change as features are added/removed as well as CPU load changes per loop duo different operations (buttons/LCD updates etc).
I do not see any compensation based on elapse time. Here is the actual code:
exLitersPerCycle = exLitersPerCycle? +?? (? CalculateInstantFlow() * 60 / ( (float) (beats_per_minute +MAX_PHASES))? )? ;
?where:
?? CalculateInstantFlow(): returns a relative pressure (from pressure calibrated reference)
?? beats_per_minute: we can consider "constant" if operator does not change it
?? MAX_PHASES: constant
It may work if it is called from a known periodic time or multiplies by an elapse factor.
But even so I would guess that it is missing a coefficient tied to the pipes and other characteristics.
I would imagine that wider pipes vs narrow pipes with same reading pressure would have different tidal volumes as wider pipes would "deliver" more volume per milliseconds
If all that is correct then I assume that we need method to find this coefficient.
Thoughts?
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Erich,
Details of my modified Orbit valve can be found in the post 1102, 1108, 1111 and 1113.
Please let me know if you have any questions.
Marc Alan
WA9ZCO
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curious about "MA's orbit expiratory valve" - do you have a link?
no problem if you're too busy - you folk are working like demons!
Reminder I'm briefing about 200 engineering students in about 10 hours, who'll be hacking ventilators for 3 days - let me know if you have anything specific for them to chew on.
e
Erich Schulz,?mbbs, mba, fanzca 0410 277 408
Wanted to let everyone know where we are.
See attached video.? ?I threw together a working airway system this morning.??
Got quite a scare-- it turns out that automobile solenoid LEAKS if you have its airway reversed.? ? Hadn't expected that was just llucky the first time.
Works perfectly, as you can see in the video.
There was a misunderstanding and we STILL don't have fully merged code that both reads the sensors and handles the user interface with Marcelo's very slick new additions.? ?I have two teams working to merge that, and I had hoped to get MYSELF out of that loop as I despearately need to pay attention to reading regulations and writing for the submission.............we've added a team in Montreal to help integrate Marcello's code with ours.?
HOORAY ILLONA!!!? She *found* the massive regulation that had all of the 201.x.x.x. numbers -- it was the 80601-2-80 thing.? ? That allowed me to begin plowing through those specific REQUIREMENTS -- and so far they are not bad at all.? ?
As soon as we can get marcelo's code to work with the sensors --- or my code to have a way to adjust the limits --- we have a working system to demo.
The UF team has now adopted MA's orbit expiratory valve!!!!!? And a huge benefit -- it makes it EASY for us to add the inspriatory pause.? ??
We re in the homestretch folks -- lets push this over the goal line!!
See attached video.
P.S.? We now have people beginning to line up with the Office of Technology Licensing to become supporting manufacturers (of their own) of the system -- I presume they are GIVING IT AWAY FREE? ?--- but if you are a manufacturer ((hint, hint Mike dishoop!!)? call the office of technology licensing at the Universtiyf of Florda and I think you'll end up with a very nice lady Ms. Hera L---I can't spell her last name---- and get signed up to get some help--- I have no idea what, I just heard it get mentioned.? ? ?I heard two large groups already mentioned as signing up.??
Gordon
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Wanted to let everyone know where we are.
See attached video.? ?I threw together a working airway system this morning.??
Got quite a scare-- it turns out that automobile solenoid LEAKS if you have its airway reversed.? ? Hadn't expected that was just llucky the first time.
Works perfectly, as you can see in the video.
There was a misunderstanding and we STILL don't have fully merged code that both reads the sensors and handles the user interface with Marcelo's very slick new additions.? ?I have two teams working to merge that, and I had hoped to get MYSELF out of that loop as I despearately need to pay attention to reading regulations and writing for the submission.............we've added a team in Montreal to help integrate Marcello's code with ours.?
HOORAY ILLONA!!!? She *found* the massive regulation that had all of the 201.x.x.x. numbers -- it was the 80601-2-80 thing.? ? That allowed me to begin plowing through those specific REQUIREMENTS -- and so far they are not bad at all.? ?
As soon as we can get marcelo's code to work with the sensors --- or my code to have a way to adjust the limits --- we have a working system to demo.
The UF team has now adopted MA's orbit expiratory valve!!!!!? And a huge benefit -- it makes it EASY for us to add the inspriatory pause.? ??
We re in the homestretch folks -- lets push this over the goal line!!
See attached video.
P.S.? We now have people beginning to line up with the Office of Technology Licensing to become supporting manufacturers (of their own) of the system -- I presume they are GIVING IT AWAY FREE? ?--- but if you are a manufacturer ((hint, hint Mike dishoop!!)? call the office of technology licensing at the Universtiyf of Florda and I think you'll end up with a very nice lady Ms. Hera L---I can't spell her last name---- and get signed up to get some help--- I have no idea what, I just heard it get mentioned.? ? ?I heard two large groups already mentioned as signing up.??
Gordon
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Re: Air Fitting Requirements
Mike,? there are standard fittings that are pin indexed in the operating room and respiratory therapy, or otherwise size fitted so that you can't put the wrong gas on the wrong line.? ?But what comes out of the BLENDER? is basically a HOSE.? ?So basically what you want to do is have a BARB FITTING at the input of your system somewhere and they will have to connect to that with a hose clamp
As for measurement lines.? ?I don't have the really thin stuff that has luer lock connections.? ?I'm using fuel tubing for very small engines.? ?it is maybe 1/16" ID? Fits on the smallest barbs in the vacuum-tube-T-fitting kit I got from an automobiile shop.??
Gordon
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Re: Help on boot loader¡®s?
Thanks, guys!
I suspect that the nano's that Dave is having problems with, turn out to be DIFFERENT from the ones that I put a bootloader on....and they may not even have one.??
I discovered that one that we both had problems with was NOT one of the ones I had put a bootloader on (it didn't have the pins on it that the ones I burned *had* -- that's how I finally recognized it)
I have found ONE more working Nano, and I have? 5 on order now from Amazon.? ?
This part was frustrating, and I thank you guys for looking it over and responding so quickly.
Gordon
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Re: UQ Ventilator Design Hackathon
All good points. I still believe that after some optimization a single nano is capable of driving a stepper motor even without Irq¡¯s.
once I have more time I will do some work for this feature.
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Marcelo Varanda
Ariel
