Direct Question for Boscoe and Fairdeal RE: WIF Probe

[cpostis]

First off I am not looking for any debate on “switches/sensors”
Please refer to this thread:
http://www.yamahaoutboardparts.com/f...e-th26676.html
I did a test on fuel and water conductivity (resistance). Using a Fluke DMM with the probes immersed in the liquid, this is a partial summary of results:
1. Tap Water 1.132 M Ohms
2. Distilled Water 2.76 Mohms
3. Sea Water 5.55 K ohms
4. Rec 90 Gasoline w/water (Probes immersed in the gas) OL (infinite)
5. Rec 90 Gasoline w/water (Probes immersed in the water) 10.93 M Ohms
6. Rec 90 Gasoline w/water (agitated) 4.775 M ohms
Here’s some pics:

[IMG]Continuity by Charles Postis, on Flickr[/IMG]

My thinking is that the 2 wire “probe” that both Yamaha and one that Racor uses is nothing but exactly what Racor calls them, “probe”. Racor says it is used to measure resistance. Therefore, my DMM leads and probes are the same as the “probe” (more or less).
What I would like to see if one or both of you have the “probe”, and you can perform tests like I did substituting the “probe” for the leads I used. I wonder if the “probe is simply two conductive tips attached to leads. There is no switch within the "probe", and the medium being measured is never a zero ohm bridge across the "probe" tips.

Or, maybe you know already!!

[boscoe99]

Sorry, I don't have a water in fuel sensor probe.

But I do know that in the case of your Fluke meter those probes can measure voltage, amperes or ohms. Depending upon the setting of course.

The Racor probes are sensing continuity through the water. Through a very high resistance. As you might have observed the electrical flow through water is very very low because of the high resistance. Therefore, another device is used to sense current flow and that device in turn can activate a light or a warning horn.

In the trim and tilt system of some Yamaha motors the circuitry was very sensitive to resistance across the trim and tilt switch. So sensitive that a special switch has to be used. An ordinary trim and tilt switch would not work. Too much resistance.

[ausnoelm]

I don't quite see the sense in playing with words and names, devices are what they are, certain manufacturers may call a similar device a probe, and sensor or anything else they choose, doesn't change the function or purpose of the device, a very simple example, you call a phone a "cell phone" we call it a "mobile" two different names for the exact same thing, radio technicians call the volume control a potentiometer, Yamaha call what amounts to the same thing for the trim gauge a sender. That said, naming conventions for troubleshooting need to be consistent, simply because we can only interpret what is written, and switches will always be switches, on or off!

[fairdeal]

As Boscoe has shown above,
almost all of these devices "work" only when they are connected to an associated "electronic apparatus" -
which generally is "measuring resistance".

I bought this last summer "to fool around with" :



It has an interesting characteristic: built-in resistance; that is to say,
even when the metal probes were connected with a test lead - "shorted"
the wiring connector terminals still measured some resistance. (I forget what)

I certainly measured a different resistance when the probe was immersed in gasoline, and different again in water.
But not a great change, IIRC.

(its intended for diesel, but I didn't have any handy).

[fairdeal]

oh, and interesting experimentation, VERY nice presentation, Chuck!

[boscoe99]

I don't quite see the sense in playing with words and names, devices are what they are, certain manufacturers may call a similar device a probe, and sensor or anything else they choose, doesn't change the function or purpose of the device, a very simple example, you call a phone a "cell phone" we call it a "mobile" two different names for the exact same thing, radio technicians call the volume control a potentiometer, Yamaha call what amounts to the same thing for the trim gauge a sender. That said, naming conventions for troubleshooting need to be consistent, simply because we can only interpret what is written, and switches will always be switches, on or off!

Does it matter that what one calls a "cell phone" a "mobile phone" or vice versa? To me it does not. To others it might.

Same with a switch being called a sensor if that is what the switch is being used for. It obviously does not matter to some (at least one, me) whereas it appears to matter to others.

Tire/Tyre
Aluminum/aluminium
Fender/wing
Hood/bonnet
Trunk/boot
And so it goes.

Just as someone that is bilingual can quickly know what is being said in either of two languages I suppose that someone knowledgeable of electrics will quickly know what is meant regardless of the specific words being used. Their, there, they're.

I report. You decide.

[boscoe99]

oh, and interesting experimentation, VERY nice presentation, Chuck!

Boscoe agrees. Good job chuckster.

[pstephens46]

Does the distance or gap between probes make a difference in readings?

[cpostis]

Does the distance or gap between probes make a difference in readings?

Pstephens,
No, within the vessels I used resistance readings did not move up or down while increasing distance. However, the readings were somewhat unstable using the Fluke DMM. I wish I still had my Simpson 260 analog meter rather than this Fluke DMM. Probably get more stable results.

Something interesting is that when I lowered the probes through the gasoline below the separation line and into the distilled water, the resistance was way higher that of the straight distilled water. Note that the gasoline is an insulator. I assumed that the probes became coated with the gasoline. When I slowly swirled the probes while submerged, the resistance decrease to a point. Still not near the straight distilled water lower resistance reading.

Fairdeal,
You said:
"It has an interesting characteristic: built-in resistance; that is to say,
even when the metal probes were connected with a test lead - "shorted"
the wiring connector terminals still measured some resistance. (I forget what)
"
Interesting indeed, you would think there would be no resistance.

I wonder if you took readings between the probe tips and lead ends (tip a-lead a, tip a-lead b, tip b-lead a, and tip b-lead b) what the readings would be? I gotta get a hold of one of these Yamaha/Racor's to test, the two lead ones!

If anything, I would think a high resistance resistor might be placed across the leads/probes internally to bleed any current if there were no water between the probes. Kind of getting hard to be clear with what I mean, do you understand?

More to come, I do have a goal for all this. Keeping it confidential until I do a little more research.

[cpostis]

Boscoe agrees. Good job chuckster.

Thanks Boscoe, Fairdeal, appreciate your gratitude!

[zenoahphobic]

Does the distance or gap between probes make a difference in readings?

It would, but not as much as changing the surface area of the probe.
As reported oil in oily water will coat the probe varying its ability to conduct. This and the saltiness has a bearing on a detection system, so one needs to know exactly what these probes are for.
I can't help myself to add that resistance cannot be measured, it is calculated; and again it needs to be determined how this "resistance" is relevant to what one wants from it.

[boscoe99]

It would, but not as much as changing the surface area of the probe.
As reported oil in oily water will coat the probe varying its ability to conduct. This and the saltiness has a bearing on a detection system, so one needs to know exactly what these probes are for.
I can't help myself to add that resistance cannot be measured, it is calculated; and again it needs to be determined how this "resistance" is relevant to what one wants from it.

Dropping the old turd into the punch bowl at the party I see.

[cpostis]

It would, but not as much as changing the surface area of the probe.
As reported oil in oily water will coat the probe varying its ability to conduct. This and the saltiness has a bearing on a detection system, so one needs to know exactly what these probes are for.
I can't help myself to add that resistance cannot be measured, it is calculated; and again it needs to be determined how this "resistance" is relevant to what one wants from it.

Correct, and thanks Zeno! Thus, I used the word “readings” rather than “measured” in my posts.

For those of you that may be interested, here’s is a good explanation of how an ohm meter works:

“Ohmmeters have a battery and a galvanometer (current meter). The two leads have a small voltage which is known. By connecting this to the circuit, the current flows from one end of the battery, through the current meter, though the resistive network and to the other end of the battery. Since the voltage is known, and the current is being measured, the resistance between A and B is calculated, and then displayed.”

[fairdeal]

Since the voltage is known, and the current is being measured, the resistance between A and B is calculated, and then displayed.”

So its actually an "amp meter" - displaying a result in ohms?


Here's a question I have had for some time:

my tank level gauge (or my trim gauge) -

reacting to the varying resistance of the "sending unit" -

putting aside that the gauge face is labeled "E - F" ( or "Down - Up")

what is the gauge actually displaying: amps? volts? ohms?

[cpostis]

Now, this is entertaining and challenging to me, others may or may not be interested.

Fairdeal stated about a diesel fuel WIF “probe” he tested:
“It has an interesting characteristic: built-in resistance; that is to say,
even when the metal probes were connected with a test lead - "shorted"
the wiring connector terminals still measured some resistance. (I forget what)”

For some reason, I think Fairdeal read the resistance across the leads with the probe gap open, maybe not?
Take a look at this diagram, I know it is a three wire and the module for the WIF detector system is built in, but note the “Trigger Threshold” of 47 KΩ.

[IMG]WIF.Diesel by Charles Postis, on Flickr[/IMG]

My readings of water resistance were much higher than that “Trigger Threshold”. After a bit of research, I believe a resistor of near 50 KΩ (could be way off) is placed in parallel between the leads and/or probes. This would change the resistance reading of tap water from 11 MΩ to about 49.77 KΩ (meter reading) , above the threshold, and trigger the alarm through the module (within the probe or remote). The resistor would also pass current always when voltage is present. Perhaps the reason for the resistor (if present) is to produce a lower “total” resistance reading for the module to trip the threshold point within a certain smaller range?

I now decided I'm going to replace my corroded Mercury fuel filter/water separator originally installed with my boat with a Racor with water detector. I can't wait to take resistance readings on it!

My confidential goal? Although I have not had a problem with water contamination, I want to see if I could design and put together an inexpensive portable probe on a sealed (conductors/wires isolated from gasoline) length of aluminum tubing to detect the presence and level of water in a tank and/or the presence of suspended water in the fuel at any level. I have been able to find any that are currently manufactured on the net or otherwise. At this time, more for entertainment than practicality. But who knows, maybe boat owners with water intrusion problems could benefit from an instrument such as this?