The ProReg - Fuel Monitoring System

The ProReg is a device that remotely monitors propane usage.

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The ProReg solves a pesky much propane is left in the tank? The ProReg uses sensors to predict the fuel level in the tank. The goal of the ProReg is to develop a highly accurate system that will eventually replace the existing two solutions available for monitoring pressurized fuel levels (scale and liquid float gauge).

Hacked my barbecue, and went from there...

Propane Monitoring - Not Easy To Do!

In order to understand why I believe the ProReg will be a breakthrough in the measurement of pressurized finite fuel systems, it is important to understand the physics behind the liquid and gas mixture that resides inside of your propane tank. When holding temperature constant, the liquid and gas mixture of your tank will always return to an equilibrium pressure. To clarify, a propane tank with 30% liquid will have the same pressure as a tank with 70% liquid on a 70 degree day. Thus, taking an on the spot pressure measurement is useless. With this project, I hope to prove that it is possible to accurately predict fuel levels without a scale or a liquid float gauge inside of the tank.

Making this technology work before the IoT revolution was not commercially viable, as each propane monitoring system would require expensive hardware and software at the sight of the measurement. With the proliferation of low energy wireless connectivity, we can finally create a cost effective system that will send data readings to the cloud where a central database computes propane usage and sends that calculation back to the user. Below is an example of the data-set provided by the maiden run of the ProReg. It shows an initial reduction in gas with the burners on medium, then the slope decreases as I turned the burners up to high, then pressure starts to increase back to its equilibrium after I turned the grill off, then It begins to decrease again after I turn the grill back on, and eventually flat-lines as the tank runs out of gas.

  • Second Effort

    Frank Vigilante01/20/2016 at 10:26 0 comments

    After a few months of analyzing the data from this summer, the ProReg was not coming along as fast as I had hoped. A few days ago I was working on a separate data analysis project and realized that if I applied the methods I was using in that project, I would likely accelerate the time it takes to get the ProReg accurately predicting fuel consumption. For that reason, I got to work on a new prototype that will hopefully bring the ProReg from concept to reality. For now, just have to finish wiring and programming the new prototype:

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RandyKC wrote 06/08/2015 at 06:19 point

I'm not trying to discourage you, just want to point out that a tank of propane has propane in two phases, liquid and gas. As the gas phase propane is used the liquid propane undergoes an endothermic phase change from liquid to gas. This is why the tank gets cool as you use it. As the gas is used and the liquid changes phase and turns into gas the pressure will rollercoaster a little but remain relatively level until all the liquid has phase changed to gas, then you will get a pressure drop. 

A way around this would be to track flow and keep a running total from when you start out with a full tank. So, 5 lbs of propane equals 5x(gas expansion for propane) equals Y liters of gas. Differential Flow can be measured with your pressure transducer across a fixed orifice. 

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RandyKC wrote 06/08/2015 at 06:55 point

Just trying to help. 

So, you are saying that as long as the flow is continuous the amount of gas is proportional to pressure? I could see that being the case, but it won't be linear and as soon as the tank temperature equilibrates then the pressure will come up again. A way to verify that would be to chart pressure over time at a fixed flow and measure tank temperature, then stop and let the temperature equilibrate then test again. I predict the pressure will be more temperature dependant than indicative of remaining propane in the tank. Tracking flow would be your best bet. I dont usually use a whole tank when I grill. 

I wonder if the rate of the pressure drop would be proportional to the amount of liquid in the tank?

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Frank Vigilante wrote 06/08/2015 at 07:00 point

Thanks I appreciate it. And to be honest, I had not thought about using my transducer to measure differential flow. I was kicking around some ideas with a hall effect sensor as a flow meter, but never thought of using pressure differential to measure flow. Wouldn't I need a second transducer for that? My only issue with that would be cost as the transducer already represents the majority of the cost of the prototype. 

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RandyKC wrote 06/08/2015 at 07:07 point

Well, a quadrature encoder on the flow control knob might work instead but would have to be calibrated. Another thought would be adding a temperature sensor as well. Then you could play around with estimating the volume of liquid remaining with the rate of pressure drop (related to heat capacity of the liquid propane).

To use the hall effect sensor were you thinking of using a metal ball in a flow tube? Those are calibrated gas dependent. A CO2 flow tube may be close, but those things are expensive.

Arrrgh, you would need two thermisters. One for the tank and one for the ambient temperature.

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Frank Vigilante wrote 06/08/2015 at 07:15 point

Haha nice! I am using a temperature sensor as well. 

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Frank Vigilante wrote 06/08/2015 at 07:21 point

Also, I am only using temp sensor(s) to measure ambient temp. I decided that measuring tank temp would be redundant because pressure is effectively temp (r^2 of .99 based on many days of just letting the ProReg sit and collect pressure and ambient temp data). I am using multiple sensors to log ambient temp though...this is being done to reduce sensor error as much as possible. 

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andres ortiz wrote 04/02/2015 at 08:07 point

why not use a system like the a/c recharge systems use and just measure the mass of the tank?

 since the gas likes to stay at a constant pressure (at a given temp) mass is the only way to go with r134a

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andres ortiz wrote 04/02/2015 at 17:48 point

not to belittle the project, it looks pretty cool.

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Frank Vigilante wrote 04/03/2015 at 03:40 point

Andres, thanks for the compliment. There are many solutions out there that use a scale to measure the weight of the tank so I wanted to take a different approach with this project. The problem I had with the commercially sold scales was that they only provided about 10% accuracy. So with 26 hours of grilling time in a tank of propane, there was a 2.6 hour window that was unknown. The purpose of the ProReg is to try to achieve much higher accuracy using back-end data.

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andres ortiz wrote 04/03/2015 at 04:56 point

can it compensate for the gas cooling during high flow rates or is that a non-issue for this application? I'm not very familiar with the flow rates of a grill.

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Frank Vigilante wrote 04/15/2015 at 03:47 point


A Piezo would be great, but when I first started this project it was based on the principal that I could find a less expensive, and more accurate way to measure gas consumption in a residential barbecue. I tried to seek out all forms of sensors and their price points before building the prototype. My recollection is that the Piezo was too expensive to justify its own utility in the first application. If you can locate a piezo with +/- 1.5% accuracy for anything under $20, please let me know.  

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Frank Vigilante wrote 04/02/2015 at 05:32 point

For all those wondering the meaning of "ProReg", there are two words for each part of the syntax:

"Pro" = Propane and/or Professional

"Reg" = Regulator and/or Register 

Its a quadruple entendre.

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Sophi Kravitz wrote 03/31/2015 at 13:17 point

Awesome project.

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Frank Vigilante wrote 04/01/2015 at 03:16 point

Thank You. I appreciate the comment!

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Bruce Land wrote 03/31/2015 at 12:21 point

I need this!

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