Is there an instrument can monitor volume of air?

Question

Is there an instrument can monitor volume of air?

ipocoyo (Mechanical)

(OP)

30 Apr 20 06:31

I am trying to measure the efficiency of a spray nozzle by measuring the amount of air that "mixes" with water as it passes through the nozzle.
The experimental rig most likely will consist of an open port for free air to pass through. What would be the best way of monitoring the volume of
air? I was thinking of adding flowmeter to the inlet port. However, I also think that any air that "miraculously" gets trapped between water droplets
will just rise to the surface and mix with the air already in the tank. Please let me know your thoughts.

Still an intern

itsmoked (Electrical) · Answer 1 · 2020-04-30 11:13:39

Not sure how nozzle efficiency relates to entrained air but okay..

I would advise that you cannot measure the air at a side port as that introduces all sorts of other effects as well such as venturi effects. You would have to make the box structure continue above just as it does below.

For the flow you can use standard heating and air conditioning balancing measurement tools. You'd place it at the top.

They look like this

Or you can do something cheesy like

Keith Cress
kcress - http://www.flaminsystems.com

ipocoyo (Mechanical) · Answer 2 · 2020-04-30 12:47:44

Hi itsmoked,

I should have rephrased my initial question better. I am just curious to see how much of air
is able to mix with the water. Would you suggest using a anemometer at the top of the vessel
as the best option? Thanks again.

Still an intern

IRstuff (Aerospace) · Answer 3 · 2020-04-30 14:37:07

The amount of air that gets entrained into the water will be tiny. The more practical way of detection is post facto; I would have a shield of some sort that can be slid into place, just below the surface of the water, and wait for the air to come back out. Obviously, the water needs to have been still for a while before the test as well.

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hacksaw (Mechanical) · Answer 4 · 2020-05-01 09:39:10

Just use a dissolve oxygen meter, they are very common.

Compositepro (Chemical) · Answer 5 · 2020-05-01 16:33:39

Where does the air exit? If it does not exit then there is no air drawn in. If you are wondering how much dissolves in the water that will be a very small volume, which could be measured by counting bubbles coming out of a tube dipped into a flask of water, with the tip of the tube about 0.1" deep into the water. That also requires the spray chamber to be well sealed except for the bubble tube allowing air to enter. Or:

https://www.google.com/search?sxsrf=ALeKk02Vbpjkx1...

ipocoyo (Mechanical) · Answer 6 · 2020-05-03 04:42:08

Hi Hacksaw,

Quote (hacksaw)
Just use a dissolve oxygen meter, they are very common.

Would this not just detect the oxygen concentration in the water? What if I needed to measure the other composites of gases in the air such as nitrogen?

Still an intern

ipocoyo (Mechanical) · Answer 7 · 2020-05-03 04:45:09

Hi Compositepro,

I'm not too sure what you mean by counting the bubbles coming out of a tube. Is there a diagram to help me understand this?
Also, I was thinking of using a rotameter instead, would this be more feasible? I have remade my initial experimental setup
based on the recommendations provided. Would this be a more practical setup? Thanks in advance!

Still an intern

hacksaw (Mechanical) · Answer 8 · 2020-05-03 18:26:57

'poligies for the delay, O2 is the cheapest, but with gas chromatigraph you can measure all the components.

That said, if you want total gas absorption for given conditions, you take a temperature controlled sample for a fixed volume and measure the density, or pull a vacuum on it and measure the gas density of the gas. Pleantin of manufacturers out there for example: Density range 1-400 kg/m3(0.001-0.4 g/cm3)

Good luck,

IRstuff (Aerospace) · Answer 9 · 2020-05-04 05:19:10

Since you're aerating the water with air, the dissolved oxygen is a representative component; besides oxygen, there's nitrogen, CO2, and argon all accounting for over 99% of air.

TTFN (ta ta for now)
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hacksaw (Mechanical) · Answer 10 · 2020-05-04 19:45:25

ipocoyo,

Have you carried out a formal material balance on your process? Does it line up with your expectations?

Basically you don't aerate water for a process by spraying it in air.

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Is there an instrument can monitor volume of air?