Goal -> Constant Vacuum in a Chamber

[nathancote]

Goal --> Constant Vacuum in a Chamber

Im working on a art piece that requires that I keep a constant vacuum in a chamber. I will soon have a pump and the chamber required but i was hoping someone could point me in the direction of a regulator that would hold the vacuum. The piece requires that the speaker playing a looping track will not be heard by the viewer outside of the small chamber. I am familiar with air compressor equipment that holds to certain pressures being outputted but not the opposite. Is anyone familiar with a device that would read the lack of atmosphere and hold it with in the chamber in line between the pump and chamber? I don't mind if the vacuum pump is engaged frequently as the sound would add to the auditory "atmosphere" of the piece.

Thanks!

-nathan

 

[Mech_Engineer]

There are lots of vacuum systems that can maintain vacuum assuming your leak rate isn't very high. Just do a search for "vacuum system" in Google and you'll find everything you need. Remember that seals are very important, and cleanliness will be important for anything going into the vacuum.

Also, keep in mind that the sound vibrations can travel through the mounting bracketry for the speaker as well; the only way to make it "perfectly" silent is to have it floating in a vacuum. Barring that, you'll have to pay very close attention to vibration dampening on the speakers mount if you want it to be silent.

 

[nathancote]

How would you recommend floating the speaker? Strong Magnets or rubber gasket to diffuse the vibrations?

Aesthetically id like the small woofer to be showing a fair amount of movement and I may be able to cause that with low sound volume.

Also, would you have a site you could recommend on the gasket to seal the vacuum?

Thanks for your response!

 

[Mech_Engineer]

Megnatically floating the speaker is an interesting idea, although probably not possible considering the speaker itself is driven by a big magnet. More feasible might be to suspend it in a chamber hanging from guide wires, where the speaker driver's travel direction is perpendicular to the guide wires.

Gaskets are a tricky subject and will depend on the size and shape of the chamber you're using, but odds are you'll need to use viton or something like it. Are you hoping to make the chamber out of something like plexiglas or Lexan?

 

[AlephZero]

More feasible might be to suspend it in a chamber hanging from guide wires, where the speaker driver's travel direction is perpendicular to the guide wires.

Even better, suspend it from something flexible like stretchy rubber cords, not stiff wires. If rubber bands are too flimsy for the weight of the speaker, try to get a bit of bungee jumping rope and unravel some strands from it. The stretchy cords used to hold objects onto car roof racks etc would also work.

 

[nathancote]

Thanks again for the responses! The chamber got in today and it will have plenty of room to create a structure to support the speaker. Bungies should work to "float" it and absorbe the sound vibrations.

Another question: It came with a gasket to place under the polycarbonate jar. Is there a material that works best to seal it to the base of the structure? The jar is similar to a bell jar.

https://www.amazon.com/gp/product/B003OBYZ3K/?tag=pfamazon01-20


It states that its a White polypropylene-gasketed plate for durability and chemical resistance. I don't think this is describing the actual gasket but rather the plate. I am not sure what the gasket is composed of.

Thanks!

 

[Mech_Engineer]

I would just use the gasket that it came with, you have to be careful with sealants or other materials because outgassing is a concern in a vacuum system, and some things work better than others in that kind of situation.

If you must bond it, I would recommend using a vacuum-compatible low-outgassing sealant like RTV-3145 or RTV-566, although they can be a little pricey. With either of the RTV's you would have to let it set for about a week to be safe and not gum up your vacuum pump.