Vision systems that can provide a linear measurement back to a PLC?

theColonel26

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theColonel26
Join Date
Feb 2014
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West Michigan
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785
I need to measure the thickness of a liquid (DC of 2) on top of water (DC of ~80)

Guided wave radars suck at this. I need to run between 1/8" and 1.5 inches the most accurate GWR I know of can only see the thickness of the liquid if it is more than 2".

So I thought a sight glass and a vision system.

Budget for this would be 5k to 12k.

The challenge will be having the vision system detect the interface layer between to liquids, but that is overcome-able even I have to die the liquid.



Recommendations?
 
How about a Magnastrictive level transmitter with one float set to float on the water and one set to float on the other substance? We do that in the Oil field. One float tells us the Oil level and one tells us the water level in the bottom of the tank.
 
So a Magnastrictive level sensor can be configured to only float on top of water regardless of thickness of oil?

What if you only had 1/8 or even a 1/4" of oil?
 
Last edited:
milldrone said:
Wouldn't a typical sight glass keep the "tank" separate from the sight glass when talking about two different specific gravity fluids? I would expect the pressure on the fluid columns to be the same, but the ratio could be different.
Click to expand...
I don't understand what you mean. I don't want the sight glass to be separate from the tank. It needs to have the same level as what is in the tank. The volume of each changes and i need to measure the level of both.
 
So a Magnastrictive level sensor can be configured to only float on top of water regardless of thickness of oil?

What if you only had 1/8 or even a 1/4" of oil?
Click to expand...

Yes you can get them with different densities so they will float on the proper medium. Like I said we do it all the time in the Oil Field.

How accurate do you need to be? What is the anticipated thickness of the oil? I am sure the thinner the layer of the oil the harder it will be to measure the difference.
 
theColonel26 said:
I don't understand what you mean. I don't want the sight glass to be separate from the tank. It needs to have the same level as what is in the tank. The volume of each changes and i need to measure the level of both.
Click to expand...

On a typical sight glass there are two connections to the tank. Once the bottom fluid covers the bottom connection there is no way for the light weight fluid to get into or get out of the sight glass. So any changes to the lightweight fluid height after the bottom fluid covers the bottom connection will not be represented in the sight glass.

Steve Bailey said:
Pressure sensor at a fixed depth combined with level sensor giving the top of the lighter fluid?
Click to expand...

+1
 
theColonel26 said:
So a Magnastrictive level sensor can be configured to only float on top of water regardless of thickness of oil?

What if you only had 1/8 or even a 1/4" of oil?
Click to expand...

Maybe you could install two magnetostrictive sensors with single float each. Then subtract the measured level of the water from from level of the lighter liquid in order for calculate the difference and consequently the level of the lighter liquid.
 
milldrone said:
On a typical sight glass there are two connections to the tank. Once the bottom fluid covers the bottom connection there is no way for the light weight fluid to get into or get out of the sight glass. So any changes to the lightweight fluid height after the bottom fluid covers the bottom connection will not be represented in the sight glass.
Click to expand...
OOOh by sight glass I just meant a glass plate in the tank wall.



kallileo said:
Maybe you could install two magnetostrictive sensors with single float each. Then subtract the measured level of the water from from level of the lighter liquid in order for calculate the difference and consequently the level of the lighter liquid.
Click to expand...
Well yes that was assumed. the question is if you have a float that is 1" thick/deep that you want to read the water level. I assume you would get a different water level reading if the oil was 1/8" thick verses 1" thick, because the oil is increasing the buoyancy of the float. I guess unless the float is adjusted to have the top of it right at the top of the water level, then the oil wouldn't affect it.
 
You can get floats that have different specific gravities. You should be able to find a float material that will sink in oil and float in water.
 

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