A device that can induce pressure difference between two regions of space is considered a pump. In a certain system, the pump that creates a vacuum is considered a vacuum pump. There are two types of vacuum pumps, one being a transfer pump and the other being a trapping pump.
What is a vacuum?
The state or degree of exhaustion in such an enclosed space.
Outer space has very low density and pressure, and is the closest physical approximation of a perfect vacuum . But no vacuum is truly perfect, not even in interstellar space, where there are still a few hydrogen atoms per cubic meter.
In engineering and applied physics on the other hand, vacuum refers to any space in which the pressure is lower than atmospheric pressure.
We firstly have to consider where the pump is, does the pump inhabit a medium ie,… outer space, free space, inner space, atmosphere, on a mountain, underwater, in a very cold place, in a very hot place, low gravity, heavy gravity, no gravity etc.
Vacuum can contain matter and even space will have a couple atoms, Suns, galaxies, ort clouds, interstellar dust, dark matter , blackholes and spontaneous appearing disappearing matter, dark matter, dirty snow ball gas, gas from planets like earth VAPORIZING into space.
A pump used for creating a vacuum. How does it work?
I suspect you want to put your pump in a tangible place like in your house or garage where I will assume to be near sea level @ 14.4 psi.
Vacuum pump is basically going to Lower the pressure of a CONTAINER, the container should be rigid because as you withdraw material/gas from the container the ATMOSPHERE will instantly begin to weigh upon the container from all sides with its pressure of 14.4psi.
See here the power of atmospheric pressure.
So how does a pump remove gas from a container?
The very best pump in the 1887 Queen catalogue gave an ultimate pressure of about 0.002 atm. A modern mechanical pump should go to pressures 100 times lower ... you can see in the diagram below the components are few an inlet/outlet, chamber and pump of a description and always try to be air tight or it will re-pressurize a defeat the purpose. And another important note as soon as this sealed units pressure is below the ambient pressure you have a vacuum and if you wish to simulate space you need very good equipment as the quality of your pump and chamber, pipes and fittings becomes very important for the sake of integrity. SEE tanker vid above.
Side NOTE if you wish to construct a vacuum to simulate space you actually cant you may achieve similar gas rarity but the vacuum you create in the atmosphere unlike space is contained, what does this imply? It means the chamber by its nature being an object has boundaries ie walls, surfaces that create the containment vessel without which the vacuum contained within couldn't exist. But space is a Doctor Strange of vacuums either the chamber is or it isnt but in any respect a powerful potential a near limitless enclosed/unenclosed void between the incredible distances between worlds . Imagine it, the latent potential in the vacuum of space right next door to our atmosphere without a need for any boundaries