Nalgene aspirator vacuum pump

Wanting to do some experimenting in a vacuum, I sought out a low-cost vacuum pump. I found all kinds, but by far the least expensive, and best-bang-for-the-buck, was an aspirator pump. These can be run on either air or water. The one I chose will use water. I got a Thermo Scientific Nalgene water aspirator pump. It is suppose to be good for a max vacuum of 28.5″Hg.

I found mine on eBay for the lowest price I could find anywhere (around $16). Here are some pics showing the unassembled pieces as they were packaged:

 

vac1 vac2

 

The threads on the aspirator are 3/8″ NPT. I needed to adapt this to my faucet, which has standard faucet threads. After a quick trip to Lowe’s you can see what I can up with:

 

vac3

 

The finished product:

vac4

 


Testing

Right away I ran into a problem. As I was trying to hook this up to my kitchen faucet, I discovered the faucet adapter was just too short. Fortunately, I had a longer one laying around that I use for the water vacuum for my aquarium, called a ‘Python brass adapter’, like this one:

Upon first testing, I must say, I was impressed by how much this thing sucks! That is, the vacuum it creates is impressive. Without a proper vacuum chamber yet, I was left to my creativity… so, I stuck the hose in a nearby empty plastic water bottle, used some plastic wrap for a make-shift seal, and had at it. In no time, the bottle was nearly completely flat. A second test, this time making use of a baby medicine syringe, I filled it partially with water, plugging one end with a rubber sheet, the other I attached my vacuum hose. Right way it began to bubble, or boil, vigorously. Awesome! There was also a noticeable temperature change, as I began with ~100F+ degree water, ending 30F or 40F degrees colder.

 

Here’s a short video demonstrating what happens to a marshmallow in a vacuum:

Here’s what’s happening:

  1. As the pressure drops, the small air pockets trapped within the marshmallow expand, causing the marshmallow to expand.
  2. As the air escapes the marshmallow, it slowly returns to its “original” size.
  3. Once I abruptly disconnect the vacuum hose, the pressure inside the jar increases rapidly, essentially “crushing” the now “hollow” marshmallow.