KELLER in the bush – August 25, 2022 – Martijn Smit – Environmental Science News

IoT Water Level Pilot Project with Surprising Result in Kololo Game Reserve

Kololo Game Reserve is located near Vaalwater, Limpopo (South Africa), with several accommodations, a fine restaurant and a swimming pool. Kololo is part of Welgevonden Game Reserve (a Big Five* game reserve), with the distinction that the area itself does not host the Big Five. In summary, Kololo is a family game reserve with its own access to the Big Five, meaning the best of both worlds.

Kololo is located in a rural area and therefore self-sufficient in water and electricity. Although Kololo is connected to the electricity grid, this grid fails from time to time, so for backup purposes, there is a diesel electricity generator on standby.

The Kololo water system

Kololo’s water system consists of 3 stages: A water well, eight accumulation tanks, and finally, the distribution of water through pipes and hoses to the lodges, restaurant and swimming pool. Kololo’s main source of water is a well at a depth of 100 m. To reach the water from the well, a borehole is drilled. Measuring the level in the well is important for predicting the stock of water in the well, because the stock is not infinite.
Water from the well is pumped over a distance of 1 km into eight tanks of 5000 liters each. These tanks are called “Jojo’s” because of the name of the manufacturer (Jojo) and are located high on a hill. In fact the Jojo works like an accumulator. From Jojo’s, the water is distributed by gravity-assisted downward pipe to the lodges and pool.

Measurement levels

Measuring the water level in both the well and the Jojo’s is important to get a good idea of ​​the current level which is representative of the water stock over a period of time. That is why in February 2020, KELLER installed a complete level measurement system in one of the Jojos, which is read wirelessly via a LoRa network. The eight Jojo are connected to each other. Thus, the level of a Jojo is representative of the level of all Jojos.
KELLER offers a wide variety of analog and digital level sensors. As an option, in addition to level and temperature which are standard measurement parameters, digital level sensors can even measure conductivity. As the data is ultimately stored in a database in KELLER’s KOLIBRI Cloud, historical data is also available over time, which provides additional insight into consumption, leaks, etc.

How to measure the water level with a pressure sensor?

Have you ever had ear pain when diving in water? You feel the weight of the water column above you. Weight is a force, calculated with the formula F = mxg, where m = mass and g = gravity. Since pressure is a force per area, we can measure the column of fluid with a pressure sensor.
Knowing the density of the fluid we can convert the pressure to length (= column of fluid) and when we know the length, area and density of the fluid we can convert the measurement to volume in liters.

Wireless LoRaWAN based system

Kololo is not the largest game reserve but nevertheless a large area of ​​3000 Hectares (4500 football fields) and therefore too large for wired sensors. This project requires a wireless IoT* solution, but because Kololo is located in a rural area, there is hardly any cellular coverage. 4G and NB-IoT (i.e. the networks provided) are therefore not available. However, Kololo has internet access.
There are several wireless IoT* systems like LoRaWAN and Sigfox. Among LoRaWAN, Loriot and The Things Network (TTN) are the best known.
The big advantage of TTN is that one can easily create local coverage by installing a TTN compatible gateway and connecting it to the Internet.
A typical local LoRa network consists of 3 basic elements.

1. A sensor or gauge (digital)
2. A LoRa transmitter that transmits the measurements
3. A LoRa gateway, the receiver, which connects to the internet via ethernet or Wifi, and retransmits the measurements to KELLER’s KOLIBRI Cloud.
In the case of Kololo, the LoRa gateway is a Laird Sentrius gateway and the LoRa transmitters are KELLER’s own ADT1 LoRa modem. To this ADT1 a KELLER series 36XW digital level sensor is connected, measuring pressure (= water level) and temperature.
The ADT1 retrieves the level from the level sensor and transmits the data, along with barometric pressure and air temperature, to the LoRa Gateway. Finally, the LoRa gateway transmits all data via the Internet to KELLER’s KOLIBRI Cloud where the data is stored.
Data can be visualized in KELLER’s KOLIBRI Cloud web application, giving you much more functionality than just data visualization.
Some of these features include exporting and printing data, converting data to other units or even calculating tank contents, to name a few.

Facility

Step 1 Install the LoRa gateway in the technical manager’s office and register it with TTN (The Things Network).
Step 2 Detect LoRa reception at the measurement point to see if the KELLER ADT1 LoRa modem can connect correctly to the LoRa gateway. When the gateway and the ADT1 connect well, it is assured that the data from the level sensor will find its way to the Internet and finally to KELLER’s KOLIBRI Cloud.
Step 3 Configure the ADT1 to register and connect to the TTN network
Step 4 Connect the PAA-36XW level sensor to the ADT1 LoRa modem and install it in or on the tank.
Installation and configuration took some time as finding the right transmit power, without boosting, had to be done with precision. This is not an area where you come back easily to change the batteries for example. After installation and configuration, the system started to measure every hour.
The next day, the first measurements were visible with a downward sloping graph. Inspection of the difference between 2 measurements overnight showed a difference of approx. 100 liters per hour.
A leak was the only possible cause. At the bottom of the tanks the leak was observed: one of the threads of the pipe was partly torn from the junction.
Thus, the system has proven itself already after one day.
The system can be extended with a KELLER Series 26X digital level sensor for drilling to get an overview of the basic water stock.

Kololo electrical system

Kololo is connected to an electricity network, but it can happen that there are power cuts. To have a backup at such times, Kololo has a diesel electricity generator.
It may happen that the supply tanks are not properly cleaned and that water enters the diesel tank when filling. Diesel theft can also occur and to mask the theft the amount of diesel taken is sometimes compensated with water. For a diesel generator, this can be a disaster. Water in an engine will cause great damage with high repair costs.
As a LoRa system cannot measure faster than once every 15 minutes, detecting a change in diesel level with just a level sensor may not always work if the level is compensated with water up to the old level within 15 minutes.
However, based on the conductivity, one can detect a change in the mixture. Water is heavier than diesel and water has a different conductivity than diesel. The variation in conductivity therefore represents the presence of water in the diesel tank.
The KELLER 36XiW-CTD series is a combined digital level and conductivity sensor. With this sensor, we can detect changes in level and conductivity, therefore detecting the presence of water in the diesel.

Conclusion

A level measurement system gives real data on fluid levels. When reading wirelessly and data stored in a database, a data history is created, giving considerable statistical insight into consumption and/or malfunctions that were previously unknown. Thus, this can lead to great savings or the prevention of unnecessary repairs and non-revenue generating issues. This system can be applied to all fluid level measurements in a variety of industries. Game reserves, boreholes, agriculture, petrochemicals and many more. Every KELLER sensor with a digital output (RS485 or SDI12) can be applied in IoT applications.

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