# Lowest possible pressure (greatest vacuum)

• infamous_Q
In summary, a vacuum is a relative thing, and it would be very difficult to create a vacuum that is equal to or greater than space.
infamous_Q
Out of curiousity..how big can vacuums get? as in..how low can the pressure be?

Well, I suppose a vaccuums pressure is 0. Are you talking about a specific application?

well i am indeed interested in how vacuums work. I've come up with an application of sorts with air quickly moving through a tube, (but it starts big gets small) so it creats a vacuum in order to get those speeds...now I am wondering how much (or how great the vacuum would have to be) to basically make the pipe implode (thinkin stainless steel here...but probably will need something stronger). and also how would the moving air exit the tube if its a vacuum inside? wouldn't it just keep it pulled in?

I believe the highest vacuum was measured in a space shuttle mission in the wake of a "shield".

THE BEST ARTIFICIAL VACUUM ever achieved is produced behind a 4-meter disk dragged through Earth orbit by the Space Shuttle. Called the Wake Shield, the deflector pushes atoms out of the way, producing a small region in which the typical distance between residual atoms is a millimeter. Judging tenuousness by this some convention, the best pumped vacuum on Earth attains a residual atom spacing ten times worse---a tenth of a mm. By comparison, the atoms between stars are spaced a centimeter apart; in the gaseous halo of our galaxy the spacing is about 10 cm; and for intergalactic voids, it's up to 10 m, the lowest density (or highest vacuum) ever measured. (New Scientist, 25 April.)
http://Newton.ex.ac.uk/aip/physnews.369.html​

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We have a large vacuum facility for the flow testing of nozzles and burners and I will tell you, when you are discussing the practicality of pulling a vacuum, the problems are exponential once you get past about 3-4 psia (in my experience). You have to be extremely careful of basic things such as pipe connections (flanges, fittings, etc...) that can create a leak. The quality of your pumps also come into play.

You'll have to think of your system like a pump pumping air. The only differerence is that instead of your tube receiving the output of the pump, it is providing the source. Therefore, you will be on the low side of the pump and thus the lower pressure. You will have to have flow through the system (system being everything including your pipe).

infamous - vacuum is a relative thing, in relation to the vacuum of space it is easy to say that air is just under 15 psi and varies based on altitude, temperature, and humidity. Its also the pressure that will support a column of mercury 760mm (29.92 inches) tall and you could look at pascals and so on, but its irrelevant to your real question.

To crush the tube you would need to have a tube weak enough to collapse with the 15psi external load. If you can't simulate that with air pressure, you could construct a simple water tank to exert the pressure on the tube to see if it would fail. Its doubtful, they use rubber hoses to carry vacums up to 27-28 inches of mercury without them collapsing.

A fun experiment. Take a 45 gallon drum, metal is preferred. Fill it to about a third or half with water. Boil off the water and while it is still steaming, put the cap back on, tightly. Step back, a little farther, just a smidgen more, there that should do it. Hit it with a stream of cold water. Oh and plug your ears, it can be a bit loud.

## What is the lowest possible pressure?

The lowest possible pressure, also known as the greatest vacuum, is the point at which there is no detectable amount of gas particles in a given space. This is known as absolute zero pressure, or a perfect vacuum.

## How is the lowest possible pressure achieved?

The lowest possible pressure can be achieved by removing as many gas particles from a given space as possible. This can be done through various methods such as using a vacuum pump or using cryogenics to freeze and remove gas particles.

## What is the significance of achieving the lowest possible pressure?

Achieving the lowest possible pressure is important in many scientific and industrial applications. It allows for the study and manipulation of particles and materials in a controlled environment, as well as the production of high quality and pure materials.

## Is the lowest possible pressure achievable in all environments?

No, the lowest possible pressure is not achievable in all environments. This is because there will always be some amount of gas particles present, even in the most controlled environments. However, scientists and engineers strive to achieve the lowest possible pressure in their specific applications.

## What are some real-life examples of the lowest possible pressure being used?

The lowest possible pressure is used in various industries and technologies, such as semiconductor manufacturing, vacuum deposition processes, and space exploration. It is also used in scientific research, such as in particle accelerators and vacuum chambers for studying materials and chemical reactions.

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