Hello, I will make a vacuum chamber. I want to use a sensor to read the pressure inside of the chamber so, I can automatically stop the vacuum pump with arduino. Can you suggest me a sensor which can sense pressures near absolute zero ?
You need a 1bara ( absolute) pressure transducer .
Something like this should do it?
This is nice thank you. But this can not measure pressures under 0,3bar. I need something more close to absolute 0 bar
Pressure sensors become more and more expensive, the lower the pressure. And of course, you can never reach zero.
What is the lowest pressure in microns that the vacuum system can be expected to achieve, assuming no leaks.
Ah, I'm sorry, my mistake.
Microns? Pressure is measured in Pascals, bar, atmospheres, inches of water, millimetres of mercury. Microns are a measure of length.
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In the professional vacuum world, microns measure the height of a mercury column in micrometers, with zero being absolute vacuum. You will also see units of Torr. 1 Torr = 1000 microns.
Vacuum pumps are often rated in terms of lowest achievable pressure in microns. Like this one.
Likewise, high vacuum pressure sensors are often calibrated in microns.
So, OP: what level of vacuum do you hope to achieve, in any valid measurement unit?
Ah, thank you! I didn't know. What a hideous bodge, using microns of mercury when the ISO standard is Pascals.
Mercury column height was the very first true measurement of pressure, made in the 17th century by Evangelista Torricelli, for whom the unit "Torr" was named.
In 1971 the unit Pascal was internationally adopted. I hope that the U.S. will follow suit within a few decades, if the nation doesn't disintegrate first.
Ah, you're talking about American practice! We in Europe dumped all that nonsense to do with the height of a mercury column decades ago. Thank goodness - the SI system is magnificent.
European history. At least the Americans accept the SI unit of meters as a useful and standard measure of the height of a mercury column, although I still see inches in the weather report.
Yea... our leaders seem to not have any vision of the future. I think the term "bickering old coots / biddys" applies to our current Congress.
Yes, isn't that bizarre? Using an SI unit of metres to indicate the height of a column of mercury as a measure of pressure!!
No, I don't think that to be bizarre at all. It was a genuine scientific advance to have a very simple way to reproducibly and reliably measure atmospheric pressure, as well as a standard unit of measure.
Yes, but that was a century or more ago. The rest of the world moved on when the massively bigger scientific advance of SI units was introduced.
Four centuries ago, in Europe.
Not the introduction of SI units. And the metre was invented in 1793.
Oh, you mean a mercury column to measure pressure? OK, understood.
Yes. The mercury column method was a brilliant and extremely significant advance.
Torricelli was a scientific hero.
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