Sensor node for liquid level measurement


I’m looking for a LoRa sensor (TTN) for liquid level measurement. I have to constantly check the water level in the pump and send a message when the level reaches a minimum and maximum value. This is especially important for my project because I try to implement a network of sensors wherever possible (e.g. I am currently using Laird nodes for temperature measurement). In other words, as a designer I build proof-of-concept. Can you recommend any devices at an average price? Nodes operated by Cayenne will be welcome. :grinning:

Hi @itpw, I do this kind of work on farms. In different situations I use the following sensors:

  • Elsys ELT2HP with Maxbotix ultrasonic range sensor.
  • RadioBridge RBS306 with Maxbotix ultrasonic range sensor.
  • Netvox RA0711 with under-water depth pressure sensor.

They all work well.

Thank you, I’m going to check them all. By the way, what about Maybe someone has some experience with this unit?

I’m working on exactly the same application. I’m going to use these products -

1m,2m,3m,4m,5m water level transmitter with 5m cable liquid level sensor with RS485 transformer module

RS485-LN RS485 to LoRaWAN Converter

The sensor is connected to the LoRa node via the RS485 interface. I have a RAK7249 gateway which receive the water level data.

Can I say, this may be more expensive than you’re wanting to pay, but it’s about half the price of a commercial solution that I am currently using which continues to fail.

Oldfield, I’m trying to accomplish something similar, but my nodes have to be off grid/without mains electric. What is your plan regarding power source? And where do you get the 24V from for the sensor?

Hi @itpw, the TEK units are very good but they are an all-in-1 unit specifically designed for being installed through the top of an above-ground liquid storage tank with the inside facing down into the tank and the outside having the electronics and antenna.

This arrangement may not be right for other types of deployment so please think carefully about your requirements for mechanical placement of the ultrasonic horn, the electronics and the antenna.

@cultsdotelecomatgmai can you please tell me more about the setup of Netvox RA0711 (better RA72611): the information on their homepage doesn’t explain how the configuration for TTN would look like and how the parameter for the sending intervall could be set to my need. If you could also indicate a price range would be fine also (didn’t find a shop so far…)

Noiasca, I have been working on this for quite a while. I have two issues, one is the water level, and the other is opening/closing a motorised valve (MV). They are both approx 500m from the barn which houses the gateway and other electronics to manage water supply and the prioritising there of. The water level is working using a commercial device so I have decided to leave that part for now … though I have purchased the two items I referenced earlier. So that means I need 24 volts for the MV. This will come as a let-down, I’m sure: I purchased a 12 volt MV!! However, I still have to find 12 volts in the middle of nowhere. I am planning to use batteries. I have been experimenting with Li-Fe batteries, PV cells and DFRobot’s “Solar Power Manager”. I have also been trying to incorporate LoRa sending back battery voltage/current, and state of charging. Haven’t been successful with that.

Does anybody know of pressure based level sensors that have more than 5meter cable between the node itself and the pressure sensor?

Hi @noiasca, I use a range of Netvox devices. They are ALL distributed with THE SAME OTAA AppEUI and AppKey. I use a “provisioning application” on TTN to get them online.

Once the devices are online on the provisioning application, the configuration of AppEUI, AppKey and operating parameters is done via downlinks. The key document that holds the uplink and downlink payload formats is called Netvox-LoRaWAN-Application-Command-V1.9.2-for-public.pdf and you should get a copy of this when you buy a Netvox device. Once the device is configured, a reset will result in a join to the target application.

My experience is that this process is a bit tedious but has been very reliable. The [UK] distributor that I use will pre-configure devices with your choice of credentials and operating parameters at an additional cost.

I’m based in the UK and purchase Netvox devices from Alliot at - I believe that they are the exclusive UK distributor. I guess you need to find a distributor based in your territory.

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Hi @AlainD, the pressure sensors that I am aware of are normal industrial 4-wire RS-485. You can extend this yourself or ask a Value-Add Reseller or local electronics workshop to extend it for you.

@Oldfield Thank you. That’s interesting. Especially since I want to connect a parallel sensor to the pump control.

@cultsdotelecomatgmai Wow, I didn’t know about Alliot’s store. Looks very promising. The LoRa devices seem to be precisely the right ones to use.

If you’re at all interested in a low cost DIY node take a look at
I have four such home-made 4-20mA water-level sensor nodes running very reliably. I use cheap SLA batteries and I got the pressure sensors for 30 quid each from ebay.

Hi @itpw

KELLER has high quality level probes with LoRa sending units. Besides the calculated liquid level based on the pressure difference it also measures the temperature in the liquid.

They can be used in KELLER’s own cloud solution where you can trigger water level alarms:
This cloud solution is ideal to test your proof-of-concept.