Best sensors for measuring fuel flow rate in vehicles

There are many ways to measure flow rate. Accurate flow rate measurement may require a positive displacement flow sensor, but they aren't usually cheap. Flow can be measured at the fuel injectors as well. Usually you can just tap into the OBD2 system to extract fuel data, because every car these days has fuel measurement already implemented. It is unlikely that a low-cost external measurement system will perform better. There also questions about safety that affect the answer. More information about your application is needed to give a better answer.

1) This device is to address short-fueling.(Yes, short-fuelling is a problem in many countries).
Not connecting with fuel pipe but fit around the tank's fuel cap so that when the vehicle is refueled, it notifies the actual volume amount going in the vehicle.

2) This is not the best sensor but to start with but can be used with fuels. e.g. similar plastic sensors for diesel. www.amazon.in/.../B093ZNNY84 . Planning to move to other sensors as we progress. If you know any better compact, cost efective,accurate sensors that can do the job, please do share.

3) Which is the simple, compact, cost effecient way to get refueling volume displayed to the users? On a seperate device or on a app or send a notification on SMS/Whatsapp? Please help share more in detail on devices available for each option & how it can be achieved?

1) This device is to address short-fueling.(Yes, short-fuelling is a problem in many countries).
Not connecting with fuel pipe but fit around the tank's fuel cap so that when the vehicle is refueled, it notifies the actual volume amount going in the vehicle.

2) This is not the best sensor but to start with but can be used with fuels. e.g. similar plastic sensors for diesel. www.amazon.in/.../B093ZNNY84 . Planning to move to other sensors as we progress. If you know any better compact, cost efective,accurate sensors that can do the job, please do share.

3) Which is the simple, compact, cost effecient way to get refueling volume displayed to the users? On a seperate device or on a app or send a notification on SMS/Whatsapp? Please help share more in detail on devices available for each option & how it can be achieved?

"but fit around the tank's fuel cap".

Surely there's just the tiniest risk, maybe I'm blowing it out of proportion (but I don't think so) that this isn't the best idea, to put dodgy Amazon hardware or your DIY circuitry around the whole general fuel area?

What's the benefit anyway. Will you argue with the fuel station that this cheap project is more accurate than their dispensing systems which might cost a thousand times more? Where will that get you?

shabaz To make an informed decision & customer awareness. I repeat, yes short fueling is an issue in many countries. This is an open design research project & so progress. Not just with close minds.

As I said in your other thread - this flow meter is not very accurate. In reality, the accuracy is usually around 10-15%, even if such "manufacturers" claim 1% it will be under best conditions (i.e. calibrated against an external reference, at a fixed flow rate). Where the flow rate is not consistent, the result will be wrong by quite a bit - below the minimum flow rate, it won't register AT ALL or will do so inconsistently.

Fuel is tricky - its volume often changes quite a bit with temperature and proper fuel pumps compensate for change in density due to temperature. Such a sensor will not natively compensate.

You may be better off filling your own fixed-volume jerry cans of known volume and transferring that to your own tank. Or just fill a can and weigh it. It seems quite a bit safer and simpler ...

- Gough

Im sorry to say it's not informed. It will be very uninformed because the user will be completely deluded if he/she thinks its accurate (or safe!). 

Sorry but i'm looking for inputs towards a resolution. Happy to take them but not interested Nay's & neighs during RnD

Gough Lui  Your inputs on accuracy makes sense. Definitely accuracy & flow is to be addressed. Can using it with Temperature/density sensors help giving more accurate levels? Would love to discuss to address the concerns and get to a resolution. Thanks.

No one really wants to put the efforts to weigh the can each time refuelling :) 

How would it even work? if the design is a ring around the fuel cap, how will the nozzle fit in it, to meter the flow, while at the same time fitting into the car? The fuel station isn't going to reduce the nozzle diameter or size just for your car. If they did that, then it wouldn't be suitable for other cars. They would have to dedicate that fuel pump for just you. I can't see them doing that but surely even you see that it is a bit of a stretch!
Otherwise, if it sticks out, then how will it detach, and how will the user remove the fuel remnants on it between each use?

All the above is by way of suggesting that it doesn't seem feasible. Is this a school project? Even then I can't see it flying for coursework. No one would realistically think any of this is feasible, in terms of safety or practicality or accuracy!

boodle said:

Can using it with Temperature/density sensors help giving more accurate levels?

Likely not ... the reason purely boils down to the design of the sensor which is a windmill vane sitting in the flow. At certain rates, flow will just flow past the mill because the casing cannot be made to match very closely otherwise it could get stuck or wear out. This is the price of cheap sensors and why such sensors aren't used in actual practice where you want an accurate value of total amount as that is the time-integral of flow.

There are calorimetric flow sensors but they're not all that much more accurate either and need to be calibrated to the heat-flow properties of the fluid. Those often run $200+ for the sensor, but it has no moving parts, so the accuracy shouldn't drift over time as much as these mechanical sensors.

Calibration of fuel pumps as required by government where I am require the use of a "reference standard measure" - i.e. a cylinder of known calibrated volume. Notice they don't measure using a "flow sensor" because what you really care about is volume, not flow rate.

boodle said:

No one really wants to put the efforts to weigh the can each time refuelling :) 

Then just buy cans of a fixed size, fill them from empty to full. I mean, these are cheap and safe options which require no major work ... nor electricity, nor complex moving parts.

- Gough

I like your negativity & not thinking from the resolution perspective. Some time it bois down to personality!

I answered you a while ago in your other thread (it's a bit confusing when you have two on the same topic.)

You probably won't like my answer any better:

A flow sensor capable of giving accurate measurements of the amounf of fuel pumped into a motor vehicle during re-fueling would have to be the same bore as the existing fuel filler and be installed properly in line with it. This would have to meet stringent regulatory requirements for safetey (especially in petrol powered vehicles). seperate approval would be needed for every vehicle type.

I don't know of an off the shelf flow sensor that would work as the core of the design.

I can't see the cost being less than a few hundred pounds/dollars per vehicle even if the product were made in reasonable numbers.

What it boils down to is that your problem (checking amount of fuel delivered into a vehicle) can't reasonably be addressed with a flow sensor of any known type.

This means that you will need to step back and look at other solutions to the problem, or invent a completely new kind of flow sensor.

MK