Why Pure Nitrogen System Evacuates Faster in 500 Microns Vacuum

• smb360rewind
In summary, two closed systems of equal size, temperature, and pressure are being evacuated using equal sized vacuum pumps. One system contains pure nitrogen while the other contains an atmospheric mix with nitrogen, oxygen, and moisture. The pure nitrogen system will evacuate quicker due to the density of gases requiring less work from the vacuum pump. Water may condense and freeze in the atmospheric mix system, affecting the evacuation process.
smb360rewind

Homework Statement

Two closed systems of the same size, temperature, and pressure. One is filled with pure nitrogen the other an atmospheric mix (nitrogen/oxygen/etc...throw in some moisture).

I want to evacuate both systems to 500 microns using equally sized vacuum pumps. Why will the pure nitrogen system evacuate quicker?

The Attempt at a Solution

My HVAC courses lightly touched on gas behavior. This scenario peaked my interest so I am seeking any explanation or direction to educational resources.

My uneducated guess is that it has to do with the densities equating to more or less work required of the vacuum pump thus change in time.

Water could be interesting: evacuation will cool the air, so water could condensate at the walls (depends on the temperature/pressure curve and the initial humidity). After a while, it will freeze (and slowly sublimate), with a possible boiling step in between.
Nitrogen and oxygen are quite similar, and argon should not be an issue. CO2... depends on the temperature.

1. Why is pure nitrogen used in the evacuation process?

Pure nitrogen is used in the evacuation process because it is an inert gas, meaning it does not react with other substances. This makes it ideal for removing air and other contaminants from a system without introducing any additional elements.

2. What is the significance of evacuating to 500 microns?

Evacuating to 500 microns means that the pressure inside the system is reduced to 500 microns of mercury, which is equivalent to a vacuum level of 99.5%. This level of vacuum is necessary for certain processes, such as refrigeration and air conditioning, to function properly.

3. How does pure nitrogen help the evacuation process?

Pure nitrogen helps the evacuation process by displacing the air and other gases present in the system. This allows for a more efficient and thorough removal of contaminants, leading to a faster evacuation time.

4. What are the other benefits of using pure nitrogen in the evacuation process?

In addition to its inert properties, pure nitrogen also has a low boiling point, making it easier to remove from the system after evacuation. It also helps to prevent the formation of moisture, which can be damaging to certain components.

5. Is pure nitrogen the only gas that can be used in the evacuation process?

No, there are other gases that can be used in the evacuation process, such as helium and carbon dioxide. However, pure nitrogen is the most commonly used gas due to its inert and easily removable properties.

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