Looking for diesel flow sensor that I can connect to ESP32

[dlj]

Interesting discussion. Made me go look at how these devices work and what kinds are available. I used to measure flow rates in existing systems through a device that measured the doppler effect. Although I did find reference to an ultrasonic device, I didn't find one that would work for the size you'd need. These also have calibration concerns - but they should be able to be attached to an existing system without adding in any additional connections.

Looking at the turbine and positive displacement type devices, I wonder what kind of back-pressure they might create? I didn't see any references talking about that.

I will be very interested in hearing what you end up getting and how well it works. I do hope you follow up with both as time progresses.

dj

[NorthCoastJoe]

Put in a day tank with a gauge in it. You will know how much you're using that way. Your fuel return must go back to the day tank too. I have a 50 liter day tank and use that to track fuel usage.

[Pizzazz]

Not easy to do. Let's assume you do 20 litres/h in, 10 litres/h out. You need an oval type sensor, something like this the Gredia Flowmeter on Amazon for $18/piece (see link below). It has 1% accuracy for 6-60l/h which is relatively good. Ideally, you also want to have temperature compensation. If that is too much work then just measure the average temperature of your return line and calibrate accordingly. For calibration, I suggest you get any transfer pump and just measure the exact amount.

Your max will be significant at low consumption. For example, if you have +1% error on the 20 l/h (+0.2l) and -1% on, say 17 l/h return (-0.17), then your error will be 0.37 l / 3 litre flow or 12%. Add this the calibration and temperature errors and it becomes +/- 20% which is significant. In reality, you do not draw 20 l at low rpm, so it is not so bad.

As others have said, I think you are better off with a day tank but be careful about the amount of return fuel and the overall temperature. Then, just say forget about it and do not worry.

https://www.amazon.com/GREDIA-Food-G...37&sr=8-3&th=1

[CaptainRivet]

Originally Posted by SailingHarmonie

Actually, the linked products are turbine meters unsuited to measuring a small diesel’s low flow rates. To get the velocity high enough the spin the turbine, the pipe has to be really small, and that makes design of a linear meter with a spinning turbine very difficult.

Low flow rates are usually a positive displacement meter. Either a rocking plate, or gear, or shuttle piston, or similar.

You are right, the turbines ones are wrong as also mainly for gas.

The last sensor is different and for a test bench for diesel common rail and for actually very small amounts from 3l/h on that I think work
It took about 5min to fill 1l of diesel in start position, disconnected after the fine filter. So we talk about around 10l per h flow minimum and that sensor has 3l as minimum.
Matron, Arimar and 2 other solutions all use hall sensor and except arimar an impeller type. So that should be sufficient also for me.

[CaptainRivet]

Originally Posted by Pizzazz

Not easy to do. Let's assume you do 20 litres/h in, 10 litres/h out. You need an oval type sensor, something like this the Gredia Flowmeter on Amazon for $18/piece (see link below). It has 1% accuracy for 6-60l/h which is relatively good. Ideally, you also want to have temperature compensation. If that is too much work then just measure the average temperature of your return line and calibrate accordingly. For calibration, I suggest you get any transfer pump and just measure the exact amount.

Your max will be significant at low consumption. For example, if you have +1% error on the 20 l/h (+0.2l) and -1% on, say 17 l/h return (-0.17), then your error will be 0.37 l / 3 litre flow or 12%. Add this the calibration and temperature errors and it becomes +/- 20% which is significant. In reality, you do not draw 20 l at low rpm, so it is not so bad.

As others have said, I think you are better off with a day tank but be careful about the amount of return fuel and the overall temperature. Then, just say forget about it and do not worry.

https://www.amazon.com/GREDIA-Food-G...37&sr=8-3&th=1

You are right, the calibration will be the tricky part.
I can use the fuel tank sensor level sensor also over time to calibrated/check/match the fuel consumption measured by the flow meters.
Yes a day tank with a fuel polishing system is also in the planning but will come later.
Cool 18$ for the sensor...not much lost and definitely enough to develop the "plug in" for home assist for a diesel flow sensor.
I connect that via an INA 219 to an ESP32 which sends then via Wlan the data to home assistant. The esp32 is in the engine room anyhow as it also sends RPM, oil pressure, oil temp, exhaust elbow temp and engine room temp. Just need fuel flow sensors and the 2x INA219 for 8$. Input sensor goes right after fine fuel filter and water separator, just a small piece of fuel line and output connects to existing supply fuel line. That's simple, return line I have to see where is a good spot. A bypass so I can simply clean the sensor or if clogged bypass it.
It's not only to monitor fuel consumption and find out what's the most efficent setup when use one and when 2 at what RPM. But also complete monitoring eg if fuel amount is lower then normal over time I see early when there is a fuel delivery problem building up, in combo with pressure if the filter are pontentially clogged and so on.

Same for water tank">fresh water tank and watermaker, both get a flow sensor with ESP32 via wlan so I see how much I use and what that the watermaker also refill what is used daily. Also this for monitoring if I eg have a leak somewhere in the fresh water system. Or less water output over time =clogged filter or membrane...

[Pizzazz]

Originally Posted by CaptainRivet

I connect that via an INA 219 to an ESP32 which sends then via Wlan the data to home assistant. The esp32 is in the engine room anyhow as it also sends RPM, oil pressure, oil temp, exhaust elbow temp and engine room temp. Just need fuel flow sensors and the 2x INA219 for 8$.

Now, you got me going on another project. I will do the same, just to see if it works well. I will use an Arduino One for now, happy to share code later. A couple of questions:

When you measure oil/temp sensors, do they interfere with the gauges or not? In other words, is the sensor feeding both the gauge and the ESP32 or it is one vs. the other? Does this depend on the INA219, optocoupler or high resistance voltage dividers?

It will be good to come up with a standardized way to monitor and alarm all funtions on the boat. A few items I have always wanted but never bothered to cutout the dashboard to install additional gauges:

- Gearbox oil pressure and temperature
- Bilge pump on count and alarm
- High water level alarm
- Fresh water operation >5min alarm (lost my 800 l water tank twice)
- Voltage monitoring for all three battery banks and alarm
- Anchor chain counter (one can use a cheap bicycle counter reed switch)
- Weather station (serial) to NMEA0183

Enjoy.
MV Ithaka

[CaptainRivet]

Originally Posted by Pizzazz

Now, you got me going on another project. I will do the same, just to see if it works well. I will use an Arduino One for now, happy to share code later. A couple of questions:

When you measure oil/temp sensors, do they interfere with the gauges or not? In other words, is the sensor feeding both the gauge and the ESP32 or it is one vs. the other? Does this depend on the INA219, optocoupler or high resistance voltage dividers?

It will be good to come up with a standardized way to monitor and alarm all funtions on the boat. A few items I have always wanted but never bothered to cutout the dashboard to install additional gauges:

- Gearbox oil pressure and temperature
- Bilge pump on count and alarm
- High water level alarm
- Fresh water operation >5min alarm (lost my 800 l water tank twice)
- Voltage monitoring for all three battery banks and alarm
- Anchor chain counter (one can use a cheap bicycle counter reed switch)
- Weather station (serial) to NMEA0183

Enjoy.
MV Ithaka

Don't need to reinvent the wheel here.
https://smartboatinnovations.com/video-tutorials/
All nicely explained, you use existing analog sensors whee you can.
I just replicate what he done , so I have all data in home assistant, also connect the cerbo GX to home assist as my BMS can connect to home assistant but not to victron. Waterflow sensors will come soon, I will then use his code for the waterflow sensors as base and do the fuel sensors.
Very good explained and he keeps all local on the boat where possible, no cloud services needed.
I use an Intel NUC because I have it instead an raspi.
I will then make with grafana a nice dashboard with all based on home assistant data.
Home Assistant much cheaper to tie sensors in then cerbo eg ruuvis tahs are great but they are super expensive, need min 10 and via HA the BT sensors are 10 till 15$.

Chain counter: but how do you wanna get the bicycle reed switch into home assistant. How about putting a little magnet on the gypsy and use a hall effect sensor count the rotations.
The water and diesel flow sensors are hall effect sensors too, so you can use the code as a base again and just modify.