Experimenting with a vacuum pump

In summary, when pumping the air out of the bell jar, one can switch off the pump by closing the ball valve between the pump and bell jar.
  • #1
DDesulgon
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Hello,
I would like to carry out a few experiments with a vacuum pump under a vacuum bell jar. However, I have no experience with this and the operating instructions could only help me to a limited extent.
Specifically, I am interested in the sequence for switching off the pump: When I have pumped the air out of the bell jar, can I then simply switch off the pump? Or will the vacuum in the bell jar damage the pump or suck the oil out of it or something similar?
What are the next steps when dismantling the experiment? Let air back into the bell, pull off the pump hose... In what order should one proceed?
 
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  • #2
Can you post links to the pump and bell jar info? Most likely it's fine to switch off the pump and just watch the vacuum gauge to be sure you don't have a leak, and then just crack the bleed valve when you are ready to return it back to atmospheric pressure, but it would be good to see the pump and bell jar info to be sure.

1652106481198.png

https://www.spectrum-scientifics.com/High-Vacuum-Pump-Deluxe-Experiment-Kit-p/1907.htm
 
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  • #3
It is common for there to be a valve at the pump to reduce the leakage back through the pump (which should be small). It may not be necessary if you don't need a hard vacuum or you don't need to maintain it for a really long time. You'll also need another valve to let air back into the chamber at some point.
 
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  • #4
Thanks for the answers and the link! Unfortunately I cannot find the information about the pump and the bell jar online.
Do I understand it correctly that the following way is safe?
- Pump off air
- Close the valve between the pump and the bell jar
- Switch off pump
- Remove the hose from valve
- open valve to let air back into the chamber (I have only the one valve)
Or could something still potentially go wrong with this procedure? And if so, what would be an alternative approach?
 
  • #5
DDesulgon said:
Hello,
I would like to carry out a few experiments with a vacuum pump under a vacuum bell jar. However, I have no experience with this and the operating instructions could only help me to a limited extent.
Specifically, I am interested in the sequence for switching off the pump: When I have pumped the air out of the bell jar, can I then simply switch off the pump? Or will the vacuum in the bell jar damage the pump or suck the oil out of it or something similar?
What are the next steps when dismantling the experiment? Let air back into the bell, pull off the pump hose... In what order should one proceed?
What kind of experiments are you wanting to do if I may ask?
 
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  • #6
DDesulgon said:
Thanks for the answers and the link! Unfortunately I cannot find the information about the pump and the bell jar online.
Do I understand it correctly that the following way is safe?
- Pump off air
- Close the valve between the pump and the bell jar
- Switch off pump
- Remove the hose from valve
- open valve to let air back into the chamber (I have only the one valve)
Or could something still potentially go wrong with this procedure? And if so, what would be an alternative approach?

I would do something like this:

Bell Jar.jpg


The ball valve should be vacuum rated, and I believe a "T port".
 
Last edited:
  • #7
  • #8
DDesulgon said:
Thanks for the answers and the link! Unfortunately I cannot find the information about the pump and the bell jar online.
Do I understand it correctly that the following way is safe?
- Pump off air
- Close the valve between the pump and the bell jar
- Switch off pump
- Remove the hose from valve
- open valve to let air back into the chamber (I have only the one valve)
Or could something still potentially go wrong with this procedure? And if so, what would be an alternative approach?
Sounds good to me. The only thing I'd worry about is the bell jar strength; but it will be fine if it's intended for vacuum use.
 
  • #9
DaveE said:
Sounds good to me. The only thing I'd worry about is the bell jar strength; but it will be fine if it's intended for vacuum use.
Just wear safety glasses.
 
  • #10
I have used a safe plastic bell jar made by Nalgene, but expensive.
 
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  • #11
I did it as described above and it worked nicely. Thank you all for the quick and excellent help, as always.
 
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1. What is a vacuum pump and how does it work?

A vacuum pump is a device that removes gas molecules from a sealed chamber to create a vacuum. It works by using a motor to create a partial vacuum inside the pump, which then draws air or gas from the chamber through an inlet valve. The air or gas is then compressed and expelled through an outlet valve, leaving the chamber with a reduced pressure or vacuum.

2. What types of experiments can be performed with a vacuum pump?

A vacuum pump can be used in a wide range of experiments, including physics, chemistry, and biology. Some common experiments include studying the behavior of gases under different pressures, creating a vacuum environment for growing crystals, and investigating the effects of reduced pressure on living organisms.

3. What are the safety precautions when using a vacuum pump?

It is important to follow safety precautions when using a vacuum pump to prevent injury or damage. Some key precautions include wearing protective gear, such as gloves and safety glasses, ensuring proper ventilation in the workspace, and regularly checking for leaks in the vacuum system. It is also important to familiarize oneself with the specific safety guidelines for the particular type of vacuum pump being used.

4. How do you maintain a vacuum pump?

To maintain a vacuum pump, it is important to regularly clean and replace any worn or damaged parts. This includes changing the oil, cleaning the inlet and outlet valves, and inspecting the pump for any leaks. It is also important to follow the manufacturer's guidelines for maintenance and to have the pump serviced by a professional when needed.

5. Can a vacuum pump be used for experiments at home?

Yes, a vacuum pump can be used for experiments at home, but it is important to take proper safety precautions and to use the pump according to its intended purpose. It is also important to have a basic understanding of how the pump works and to follow instructions carefully. If unsure, it is best to consult with a professional or conduct experiments under the supervision of an experienced individual.

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