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Liquid detecting floor pad

by sapia
Tags: detecting, floor, liquid
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Danger
#19
May26-13, 12:51 AM
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Quote Quote by CWatters View Post
using AC might be a better option
Possibly, but I suspect that the single "AA" battery case that s/he showed might have difficulty providing that.
ChrisJA
#20
May26-13, 01:46 AM
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Quote Quote by Danger View Post
Ah, yes. And the first line under "Features" specifies "conductive fluid sensing cable". I repeat myself by saying, "What if the fluid that he wants to detect doesn't conduct?"
If you are expecting a flood of cooking oil then use a float switch. Only trouble is that you need quite a lot of liquid to turn it on.
Float Switch
Danger
#21
May28-13, 04:28 AM
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Quote Quote by ChrisJA View Post
If you are expecting a flood of cooking oil then use a float switch.
I first started dealing with float switches in 1959. They are not suitable for this application.
ChrisJA
#22
May28-13, 11:17 AM
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Quote Quote by Danger View Post
I first started dealing with float switches in 1959. They are not suitable for this application.
The requirement was did not give a detection level threshold.

OK then. If you must detect a non-conductive liquid and you can't wait until the level is two inches above the floor, one common why is a capasitive switch.

It looks like the conductive sensor in the it has two electrodes separated by a small distance. But in this case the electrodes form a capacitor. The dielectric constant of air is different from oil.

The trouble is how to clean the oil out of the sensor, the mechanical design that lets the liquid in and out will be hard if you are dealing with a thick, viscous liquid that was only enough depth to make the floor wet.

These sensors are used for airplane fuel sensors. They make the capacitor with two concentric metal tubes. But the tank has some depth, If you need to detect only 0.1 mm of liquid maybe design a pattern of copper on a printed circuit board and lay the PCB copper side down and track capacitance.

OK, one last idea. This could detect even one drop. Use a video camera aimed at the floor.
Danger
#23
May28-13, 07:38 PM
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Quote Quote by ChrisJA View Post
OK, one last idea. This could detect even one drop. Use a video camera aimed at the floor.
That's the first thing that I suggested, back in post #3.


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