Sensor - the difference between gasoline and diesel

Thread Starter

Motanache

Joined Mar 2, 2015
511
It is useful to design a sensor to differentiate between gasoline and diesel.

Both do not conduct electricity.
But they are very different!
Diesel is a lubricant.
Gasoline is a solvent.
 

drc_567

Joined Dec 29, 2008
1,088
A sensitive smoke alarm detector may be capable of sensing the volatile components of gasoline, which can evaporate at room temperature. Diesel is less volatile, having a boiling point greater than water.
 

AlbertHall

Joined Jun 4, 2014
11,102
A sensitive smoke alarm detector may be capable of sensing the volatile components of gasoline, which can evaporate at room temperature. Diesel is less volatile, having a boiling point greater than water.
There are flammable gas alarms available so they should detect petrol.
 

crutschow

Joined Mar 14, 2008
26,735
It's certainly possible to sense the difference between the two.
It's the application and cost of the sensor that determines how you would do it.
 

drc_567

Joined Dec 29, 2008
1,088
There are flammable gas alarms available so they should detect petrol.
... A good suggestion.
The smoke alarm in the kitchen here seems to be hyper-sensitive, going off when there is any trace of smoke, steam, or even hot air from the open oven door.
 

wayneh

Joined Sep 9, 2010
17,027
Freezing point is yet another potential method.

The choice of method depends on the context, the budget and so on. All the things we haven't heard yet.
 

Thread Starter

Motanache

Joined Mar 2, 2015
511
Refractive index. But it differs little, only at the third significant digit. That's hard to do in diy.
1614627848302.png
It's not exactly what the figure should be. I haven't found a better one.

How to measure the refractive index with sufficient precision, not accuracy?

The refractive index is n = c / v

1614628978995.png
If we measure a fixed distance with this laser module ....
It will give different results depending on the refractive index of the environment through which the light passes.

The accuracy of this module is 5% Too imprecise to detect the small difference.

1614629470625.png
 

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Thread Starter

Motanache

Joined Mar 2, 2015
511
1614630255849.png

Let's measure the dielectric constant, again they are very close.

However, the viscosity differs a lot.

 
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wayneh

Joined Sep 9, 2010
17,027
From those tables, viscosity has good discernment but is not trivial to measure.
I think it could be trivial but we don't know the constraints. Flowrate thru a small orifice at controlled temperature would do it. Or pressure drop across an orifice at a defined flowrate.

Density isn't hard to measure either, depending on what techniques are allowed.
 

sparky 1

Joined Nov 3, 2018
488
A material composition that reacts with one vapor and not the other would allows that distinction.
If increased sensitivity is needed the size of the receptor area and the number of receptors increases sensitivity.
Dogs can be trained to sniff out a variety of liquid vapors. It is the number of receptors or larger sensors that do that.
The metod of samplng could change but sensing 3 out of 5 properties could show a diffence in data.
 
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