Thanks for the information. We just got 3 brand new flow controllers without really knowing how to use them. We are just following the instruction manuals. I'm trying to explain to my coworkers that you have to FLOW the gas. You can just stopper it into a chamber and say DONE. We want only a small amount to generate small bubbles in liquid. But we don't need a bubble bath, we need a few bubbles. So i'm suggesting we mix our gasses and then sample FROM the gas stream. I think it's best for us.
Thank you for learning me something better then I had known before hand. Love your stuff no matter what you call your channel, always informative and interesting to boot.
Always enjoy your well done videos with clear explanations. The pleasure of a good class/lab lecture without the commute and cranky professor..LOL Thanks!
At 1:56, that is just one of the ways to measure gas flow. Another very interesting way to measure gas flow is using the coriolis force. By having a tube that goes in a square, and exciting this structure with a current in a magnetic field (lorentz force), we can observe the motion this makes. By now having a flow through that hollow tube, this movement will change due to the coriolis force, which is caused by the mass flow. This is of course all a MEMS. The advantage of this method is that you can measure far more accurately how much the mass flow is. You can also measure other things like viscosity. A downside is that it has an upper limit to how much massflow it can actually measure, in contrary to the heater/thermocouple measurement. That is why companies like bronckhorst often combine both of these sensor types to achieve a higher dynamic range of massflow.
holy cow i now understand why and how to calibrate a mass flow controller for a given gas, probably for deeper engineering behind it one has to change RTD (resistive temperature detector) for the given gas
Always something interesting to show, I see. Thanks. Am I understanding the way it works correctly. At 2:37ish the coils are providing the heat and the temperature sensing is being done my measuring the temperatures of the coils? That makes sense in regard to your temperature profiles since the incoming gas would take more heat from the first coil than the second coil, since the greater the temperature difference the more efficient the heat transfer. The gas is still cool at the first coil so there's more efficient heat transfer and so the coil gives up more heat making that coil cooler. When the gas gets to the second coil, the gas is heated so there's a smaller temperature difference and so a less efficient heat transfer. The second coil therefore doesn't give up as much heat and remains hotter.
I think there are a few different ways to implement this, but most setups probably have a wheatstone bridge where the two coils are two legs of the bridge. This way, the differential resistance can be measured very accurately. There is probably circuitry to compensate for overall temperature shifts too. The moving gas carries the heat from the first coil to the second, so if both coils were emitting exactly the same thermal energy, the second coil would be hotter, yes.
Applied Science I don't think the gas carries heat from the first coil to the second coil, especially if the two coils are at the same temperature. The gas would be at the same (doubtful) or lower temperature as the first coil so it would be at the same or lower temperature than the second coil too. Heat would only move from the coil (higher temperature) to the gas (lower temperature). That's why I figured it had to do with different heat transfer rates. But mainly I was just wondering if the coils were providing the heat and the sensing, which it sounds like they are from your reply.
RimstarOrg Heat .is. introduced in the first coil, The expected heat transfer difference is meaured as temperaure (current used to maintain a stable temp) in the second coil equals density.
Gets me thinking of variometers - instruments glider pilots use to measure their ascent rate in rising air. I had a simple pellet gauge/ flask vario in the 70's but I suspect modern electronic versions use something like this.
I used a anemometer for air flow measurements. It used a heater and a thermocouple down stream. That's basically what your device does. So I guess that was really a mass flow measurement device. they are designed to be inserted in air ducts.
To me, it feels a little bit generic - "Ben Krasnow" is a stronger brand, but probably only because I've been following you for a while anyway. Love your work, either way!
Just subscribed to your channel recently but I like the name and logo think it makes sense for a lot of the stuff your showing/doing, particularly for newcomers. I'm a programmer type myself so this is a bit outside of my domain but you do a good job of breaking down lots of concepts (particularly related to the transistors one you did and burning them out, because of not knowing to put a resistor on the base). Thanks for the informative videos.
I like the new name just fine, but I did a double-take when I saw this video posted, because I also follow Applied Materials, who obviously would know a lot about MFCs!
I'm just wondering, a lot of cars nowadays use "MAF" (Mass air-flow) sensors to measure the amount of air coming into the engine, and they use a similar technique to measure with. Do you think these would work well enough to create a mass flow controller for a fraction of the cost? (Assuming you acquired the MAF sensor used from a junkyard or something)
Applied Science I think the name is great. Nobody likes something too fancy for the sake of being fancy - a metaphor for you - what good is it to be-able to say fancy words, but not know the meaning or application - it defeats the purpose. For this reason I think the name is great and well applied to the science field. Alot of scientists publish work with little or no relevance to 'the real world.' Applied science is taking the understanding of principles and putting them into practice on a home based level; something very few can actually do well.
I know. I was chuckling because I like using LM324s in low-speed circuits, and someone once criticized me for using "the worst" op-amp possible. Seeing it in a commercial product made me laugh. It's inputs and outputs can go to the negative rail, but only within 1.5V of the positive one. There are other opamps in the MFC, and they may have bigger voltage requirements. One of these MFCs had all of its chips sanded to remove the markings!
Applied Science Yeah it depends on what you need it do do. I don't see why one would use a more expensive component when an LM324 would do it just fine.
very old UNIT elastomer, (rubber seals) MFC. solenoid valve is very hard to stably set... valve must be stable. 10 cc very hard to accurately set to specification.
Yes, but this would measure volume flowrate. It's possible to add temperature and pressure sensors to a volume flowmeter, and calculate mass flow. Most fuel injection systems for modern cars have these separate sensors, and combine all of the data to determine how much fuel to inject.
There was no real reason in particular for the name change. It just happens that most of the stuff that I want to talk about is applied science, and not really related to me in particular. In terms of descriptive names, "applied science" tells people much more about the channel than "Ben Krasnow".
Thanks for your video! But could you please help me with this problem. We have the same system in our brewery. And the thing is that the Rotameter shows 17 Nm3/h and the mass flow shows 22 kg/h. When i do the conversion, it seems not correct. The rotameter is calibrated at 6 bar 20 deg. C and our supply air is at 5.5 bar and 30 deg .C. I check the density of air at that condition should be 6.32 kg/m3, but it seems like they are programmed at standard condition with the density of air is ~ 1.2 kg/m3.
did you find a solution to this problem? i would be interested to learn about it. I am about to use rotameters (designed for air) to use for hydrogen gas flow and I do not have the luxury of comparing it with a mass flow meter. So if I could learn something from you than I can be prepared for my experiments ;)
Thanks for the video. used mfc for a long time without knowing how it works! I have a question: we know it works well for gaseous content (N2, O2, Ar). How will it work for vapors (ethanol, water, acetone vapors generated from the vaporized liquids)? I was looking at how to introduce weird gases into my chamber. Do share some wisdom if u have :P
Hi Tim, It can be clogged with vapors,and depends also of temperature of the fluids and MFCs. You can use an MFC with a large capillary like Bronkhorst supply ( LowDP series )
Hi, I'm a bit confused... You said that 12 psi is about 2 atm, but from another source I get that 1 psi is about 0.068 atm, and consequently 12 psi is about 0.816 atm. Am I missing something?
It's very common for pressure gauges to read zero at atmospheric pressure. In such cases, reading a zero on the gauge indicates 14.7 psi or 1 atm. If the gauge reads 12 psi, that is almost 2 atm (14.7 + 12 psi). The confusion can be avoided by saying "gauge pressure" or "absolute pressure".
I am trying to understand if it is possible to build digitally controlled system that could cycle a propane/oxygen surface mix burner on for a set amount of time and then back off again. I am designing a robot that will be controlled by Pololu Maestro Servo Controller. This will control multiple servos that will primarily power gear racks for linear movement. An element of the robot is the flame that I am hoping I can also control with the Pololu Maestro as well. Is it possible to turn oxygen and propane lines on and off with a solenoid valve and somehow have the mass flow controllers located after the solenoids to deliver the precise flow I am looking for? Or do the mass flow controllers have to be manually turned on and off for each cycle. Sorry for all of the questions. I'm just starting on this project and after many hours of searching, watching, reading I have no idea where to turn for answers. The linear movement aspect of the robot is quite simple but understanding how to or even if I can cycle the flame on and off precisely still eludes me. Do you have any suggestions? Thanks for any help you can provide.
Greeting; Can you please release the name of the gas mass flow controllers (both electromagnetic & manual) as well the software use to control & reading them. Thanks a lot
The inlet and outlet connection of that mass control is called VCR. You will have a leak if you connect gas tubing that way. Here is the 1/4 female VCR to 1/4 tube adapter. m.ebay.com/itm/321787470755
Applied Science What is the actuator for the valve and the valve type/mechanism? Also, did you measure, or find out from specs what the change time (to within 5 or 10% or something) is to stabilize/steady-state from a given set point to another? Also as a side note, you should probably enunciate the A sound more because it sounds like you're saying roto meter. I also prefer the pronunciation "rotam eter" because it sounds less weird, although it is preference and I think both are OK.
It's true, 14.7 psi is one atm, so 12 is a little shy. My rotameter is calibrated for air, and I was running pure oxygen in this test, but air and oxygen have very similar density and thermal properties. The calculations with the rotameter were just for sanity check to make sure the MFC was working reasonably well.
tuberlook1 psig ="psi gauge" meaning "the pressure above atmospheric". You should add 14.7 to all normal pressure gauge readings to get the absolute pressure. The rotameter correction factor is based on the ratio of absolute pressures, so sqrt((14.7+12)/(14.7))
I just realized that you go through infinity times more argon per month than almost every other person on Earth. What's that like? How does it feel? What's your monthly argon budget?
I don't buy argon that often. I'm guessing that the biggest users of argon as a group would be TIG welders. I have a cheap TIG welder, and that is why I already had an argon bottle before embarking on the sputtering stuff. When welding, a typical flow rate is 15 CFH, or about 7000 sccm!
JustOneAsbesto You breath quite a bit of Argon; It comprises almost 1% of the atmosphere. Perhaps this isn't the same as using it, but it sure means you've worked with a lot of it... :)
Nice video, In the real world though, those instruments are not calibrated with the specific gas (i.e. the one that the user will measure). Some manufacturers like Bronkhorst, Brooks and Sierra Instruments deliver instruments for all gases which were factory-calibrated only with air (or N2). They provide the user with a K-Factor whose exactitude has not been proven. Some other companies like Horiba-STEC do not even use K-factors but Polynomial correction curves. K-factors give errors…. Another point, and not the least of them, These traditional meters like the capillary principle are a metal tube that gets heated, as a consequence these units drift over time and need to be calibrated and of course adjusted at least once per year. An alternative is to use mass flow meters/controllers with MEMS sensors technology which, conversely, are always factory-calibrated with the "real gas" so to obtain the best possible accuracy. These units are extremely stable, with clean gas they can stay stable for more than 10 years.
Some of his information is correct but I hope he is not in the mass flow business because he has NO idea what he is talking about! That pot that is exposed with a hole in cover is the zero pot.
![[Full Version] Coriolis Mass Flow Meter: The Principle of Operation](/img/n.gif)
This channel is literally better than an undergraduate degree
Thanks for the information. We just got 3 brand new flow controllers without really knowing how to use them. We are just following the instruction manuals. I'm trying to explain to my coworkers that you have to FLOW the gas. You can just stopper it into a chamber and say DONE. We want only a small amount to generate small bubbles in liquid. But we don't need a bubble bath, we need a few bubbles. So i'm suggesting we mix our gasses and then sample FROM the gas stream. I think it's best for us.
Thank you for learning me something better then I had known before hand. Love your stuff no matter what you call your channel, always informative and interesting to boot.
Always enjoy your well done videos with clear explanations. The pleasure of a good class/lab lecture without the commute and cranky professor..LOL
Thanks!
At 1:56, that is just one of the ways to measure gas flow. Another very interesting way to measure gas flow is using the coriolis force. By having a tube that goes in a square, and exciting this structure with a current in a magnetic field (lorentz force), we can observe the motion this makes. By now having a flow through that hollow tube, this movement will change due to the coriolis force, which is caused by the mass flow. This is of course all a MEMS.
The advantage of this method is that you can measure far more accurately how much the mass flow is. You can also measure other things like viscosity.
A downside is that it has an upper limit to how much massflow it can actually measure, in contrary to the heater/thermocouple measurement. That is why companies like bronckhorst often combine both of these sensor types to achieve a higher dynamic range of massflow.
holy cow i now understand why and how to calibrate a mass flow controller for a given gas, probably for deeper engineering behind it one has to change RTD (resistive temperature detector) for the given gas
Always something interesting to show, I see. Thanks.
Am I understanding the way it works correctly. At 2:37ish the coils are providing the heat and the temperature sensing is being done my measuring the temperatures of the coils? That makes sense in regard to your temperature profiles since the incoming gas would take more heat from the first coil than the second coil, since the greater the temperature difference the more efficient the heat transfer. The gas is still cool at the first coil so there's more efficient heat transfer and so the coil gives up more heat making that coil cooler. When the gas gets to the second coil, the gas is heated so there's a smaller temperature difference and so a less efficient heat transfer. The second coil therefore doesn't give up as much heat and remains hotter.
I think there are a few different ways to implement this, but most setups probably have a wheatstone bridge where the two coils are two legs of the bridge. This way, the differential resistance can be measured very accurately. There is probably circuitry to compensate for overall temperature shifts too. The moving gas carries the heat from the first coil to the second, so if both coils were emitting exactly the same thermal energy, the second coil would be hotter, yes.
Applied Science
I don't think the gas carries heat from the first coil to the second coil, especially if the two coils are at the same temperature. The gas would be at the same (doubtful) or lower temperature as the first coil so it would be at the same or lower temperature than the second coil too. Heat would only move from the coil (higher temperature) to the gas (lower temperature). That's why I figured it had to do with different heat transfer rates. But mainly I was just wondering if the coils were providing the heat and the sensing, which it sounds like they are from your reply.
RimstarOrg Heat .is. introduced in the first coil, The expected heat transfer difference is meaured as temperaure (current used to maintain a stable temp) in the second coil equals density.
Gets me thinking of variometers - instruments glider pilots use to measure their ascent rate in rising air. I had a simple pellet gauge/ flask vario in the 70's but I suspect modern electronic versions use something like this.
oh your changed your channel name. i like it.
That was some useful explanation. Thanks and well done!!
Last time i disassembled flow meter, it had Analog Blackfin DSP :) (we use it in our lab, for HHG generation)
I used a anemometer for air flow measurements. It used a heater and a thermocouple down stream. That's basically what your device does. So I guess that was really a mass flow measurement device. they are designed to be inserted in air ducts.
norxcontacts I'm curious to know why you don't like the channel name, and what sort of name you'd prefer.
To me, it feels a little bit generic - "Ben Krasnow" is a stronger brand, but probably only because I've been following you for a while anyway. Love your work, either way!
Just subscribed to your channel recently but I like the name and logo think it makes sense for a lot of the stuff your showing/doing, particularly for newcomers. I'm a programmer type myself so this is a bit outside of my domain but you do a good job of breaking down lots of concepts (particularly related to the transistors one you did and burning them out, because of not knowing to put a resistor on the base). Thanks for the informative videos.
I like the new name just fine, but I did a double-take when I saw this video posted, because I also follow Applied Materials, who obviously would know a lot about MFCs!
I'm just wondering, a lot of cars nowadays use "MAF" (Mass air-flow) sensors to measure the amount of air coming into the engine, and they use a similar technique to measure with. Do you think these would work well enough to create a mass flow controller for a fraction of the cost? (Assuming you acquired the MAF sensor used from a junkyard or something)
Applied Science
I think the name is great. Nobody likes something too fancy for the sake of being fancy - a metaphor for you - what good is it to be-able to say fancy words, but not know the meaning or application - it defeats the purpose. For this reason I think the name is great and well applied to the science field. Alot of scientists publish work with little or no relevance to 'the real world.' Applied science is taking the understanding of principles and putting them into practice on a home based level; something very few can actually do well.
I like the name change.
Nice video, like all your videos!
Not a bad explanation. I own a company that has calibrated, repaired and sold MFC's for 37 years.
this dude is my nigga
Great video as always Ben
Very curious about how the proportional valve works? Is it just a needle valve balanced between a spring and the coil current?
As far as I know the LM324 isn't the best of OP-AMPs. It's very basic and it is the component that needs the +/-15V supply,
I know. I was chuckling because I like using LM324s in low-speed circuits, and someone once criticized me for using "the worst" op-amp possible. Seeing it in a commercial product made me laugh. It's inputs and outputs can go to the negative rail, but only within 1.5V of the positive one. There are other opamps in the MFC, and they may have bigger voltage requirements. One of these MFCs had all of its chips sanded to remove the markings!
Applied Science Yeah it depends on what you need it do do. I don't see why one would use a more expensive component when an LM324 would do it just fine.
The biggest and common problem of MFC is when the the capilairy tube clodged, sadly I never know how to clean it up.
Well done sir!
youre a really smart. i always like your videos!
High Valued Stuff. thanks as always;
Which kind of electronic circuits you use can you send the circuit details???
very old UNIT elastomer, (rubber seals) MFC. solenoid valve is very hard to stably set... valve must be stable. 10 cc very hard to accurately set to specification.
These things are great, nice explanation too. Do you know what temperature do the coils get up to in yours?
good stuff, as always...
Would a combination of automotive sensors be precise enough for your purposes...?
Is something similar used in IC engines with Electronic control?
Hey what? Applied Science? Ben Krasnow was getting immortal soon.
I read that as "Ben Krasnow was getting immoral soon". Time to put on glasses, because that CAN'T be true.
Could you use a fan? the energy generated by it would be the flow.
Yes, but this would measure volume flowrate. It's possible to add temperature and pressure sensors to a volume flowmeter, and calculate mass flow. Most fuel injection systems for modern cars have these separate sensors, and combine all of the data to determine how much fuel to inject.
Applied Science Great! Thank you
I like Ben Krasnow better... it Branding of his specific style and class of video... What storm causes the change?
There was no real reason in particular for the name change. It just happens that most of the stuff that I want to talk about is applied science, and not really related to me in particular. In terms of descriptive names, "applied science" tells people much more about the channel than "Ben Krasnow".
Thanks for your video! But could you please help me with this problem. We have the same system in our brewery. And the thing is that the Rotameter shows 17 Nm3/h and the mass flow shows 22 kg/h. When i do the conversion, it seems not correct. The rotameter is calibrated at 6 bar 20 deg. C and our supply air is at 5.5 bar and 30 deg .C. I check the density of air at that condition should be 6.32 kg/m3, but it seems like they are programmed at standard condition with the density of air is ~ 1.2 kg/m3.
did you find a solution to this problem? i would be interested to learn about it. I am about to use rotameters (designed for air) to use for hydrogen gas flow and I do not have the luxury of comparing it with a mass flow meter. So if I could learn something from you than I can be prepared for my experiments ;)
A new username can be confusing, but nice video as always.
Thanks for the video. used mfc for a long time without knowing how it works! I have a question: we know it works well for gaseous content (N2, O2, Ar). How will it work for vapors (ethanol, water, acetone vapors generated from the vaporized liquids)? I was looking at how to introduce weird gases into my chamber. Do share some wisdom if u have :P
Hi Tim, It can be clogged with vapors,and depends also of temperature of the fluids and MFCs. You can use an MFC with a large capillary like Bronkhorst supply ( LowDP series )
Hi, I'm a bit confused... You said that 12 psi is about 2 atm, but from another source I get that 1 psi is about 0.068 atm, and consequently 12 psi is about 0.816 atm. Am I missing something?
It's very common for pressure gauges to read zero at atmospheric pressure. In such cases, reading a zero on the gauge indicates 14.7 psi or 1 atm. If the gauge reads 12 psi, that is almost 2 atm (14.7 + 12 psi). The confusion can be avoided by saying "gauge pressure" or "absolute pressure".
Applied Science
Oh OK, so 12 psig, got it! Thanks!
How much power input the mass flow meter requires to measure the flow?
I am interested in making a MFC work to control some gases in an experiment. Can you tell me the wiring you used to make your mfc work?
I am trying to understand if it is possible to build digitally controlled system that could cycle a propane/oxygen surface mix burner on for a set amount of time and then back off again. I am designing a robot that will be controlled by Pololu Maestro Servo Controller. This will control multiple servos that will primarily power gear racks for linear movement.
An element of the robot is the flame that I am hoping I can also control with the Pololu Maestro as well. Is it possible to turn oxygen and propane lines on and off with a solenoid valve and somehow have the mass flow controllers located after the solenoids to deliver the precise flow I am looking for? Or do the mass flow controllers have to be manually turned on and off for each cycle.
Sorry for all of the questions. I'm just starting on this project and after many hours of searching, watching, reading I have no idea where to turn for answers. The linear movement aspect of the robot is quite simple but understanding how to or even if I can cycle the flame on and off precisely still eludes me. Do you have any suggestions? Thanks for any help you can provide.
Yes, if you use a mass flow controller with digital capabilities, then you can easily write setpoint slopes to open, control and close the valve.
Greeting;
Can you please release the name of the gas mass flow controllers (both electromagnetic & manual) as well the software use to control & reading them.
Thanks a lot
Wouldn't the rotometer read accurately on the output side of the mass flow controller?
Yes, I think it would. I should have tested it.
what SCCM range are they?
The inlet and outlet connection of that mass control is called VCR. You will have a leak if you connect gas tubing that way. Here is the 1/4 female VCR to 1/4 tube adapter.
m.ebay.com/itm/321787470755
Applied Science What is the actuator for the valve and the valve type/mechanism?
Also, did you measure, or find out from specs what the change time (to within 5 or 10% or something) is to stabilize/steady-state from a given set point to another?
Also as a side note, you should probably enunciate the A sound more because it sounds like you're saying roto meter. I also prefer the pronunciation "rotam eter" because it sounds less weird, although it is preference and I think both are OK.
That is an old Unit UFC-1000 from the 80's. It has a solenoid valve.
I have an idea for your next project, build an Einstein refrigerator! Never seen one in operation or heard any specs!
TheAmmoniacal anything based on his work is not at all based in reality
Am I missing something or is 12 PSI not even 1 atmosphere ?
It's true, 14.7 psi is one atm, so 12 is a little shy. My rotameter is calibrated for air, and I was running pure oxygen in this test, but air and oxygen have very similar density and thermal properties. The calculations with the rotameter were just for sanity check to make sure the MFC was working reasonably well.
Sorry I thought you said in your video that 12 psi was = to 2 atmospheres, my mistake, thanks for the reply.
tuberlook1
psig ="psi gauge" meaning "the pressure above atmospheric". You should add 14.7 to all normal pressure gauge readings to get the absolute pressure. The rotameter correction factor is based on the ratio of absolute pressures, so sqrt((14.7+12)/(14.7))
I just realized that you go through infinity times more argon per month than almost every other person on Earth.
What's that like? How does it feel? What's your monthly argon budget?
I don't buy argon that often. I'm guessing that the biggest users of argon as a group would be TIG welders. I have a cheap TIG welder, and that is why I already had an argon bottle before embarking on the sputtering stuff. When welding, a typical flow rate is 15 CFH, or about 7000 sccm!
Well, any amount is infinity times more than (I'm guessing) at least 6.5 billion people use.
That would make me feel special, if I used argon.
JustOneAsbesto You breath quite a bit of Argon; It comprises almost 1% of the atmosphere. Perhaps this isn't the same as using it, but it sure means you've worked with a lot of it... :)
i like the older channel name better..
...ever heard of Forrest Mims?
Nice video, In the real world though, those instruments are not calibrated with the specific gas (i.e. the one that the user will measure). Some manufacturers like Bronkhorst, Brooks and Sierra Instruments deliver instruments for all gases which were factory-calibrated only with air (or N2). They provide the user with a K-Factor whose exactitude has not been proven. Some other companies like Horiba-STEC do not even use K-factors but Polynomial correction curves. K-factors give errors…. Another point, and not the least of them, These traditional meters like the capillary principle are a metal tube that gets heated, as a consequence these units drift over time and need to be calibrated and of course adjusted at least once per year. An alternative is to use mass flow meters/controllers with MEMS sensors technology which, conversely, are always factory-calibrated with the "real gas" so to obtain the best possible accuracy. These units are extremely stable, with clean gas they can stay stable for more than 10 years.
0 - 5 vdc valve drive circuit, 0 - 5 vdc sensor circuit...
Why do you need to do this? ha! I'm just asking.....what is you line of work that you get to "play" in you lab all day??!?!?!?
Oh... you changed the channel name. Had me confused. "I didn't subscribe to a channel of this name."
I think it's time for u Ben to have 2 or 3 kids...don't u love kids? U can explain all this to them :)
PIETRO RANDAZZO you ever seen idiocracy? It's kinda true how they explain how smart people breed less.
Dig ur chnl......subbbbbz. Do stuff on lasers pleaseeeee. Chrys on top
Some of his information is correct but I hope he is not in the mass flow business because he has NO idea what he is talking about! That pot that is exposed with a hole in cover is the zero pot.
Ben I'm a fan, but "applied science" sucks.
MilkCap you suck.