Industrial Tank Level Monitoring

Application Notes

Application Background                                                                                                                                                                                          Printer Friendly Version

Measurement of levels in tanks is important across many industrial applications. There are many tank monitoring applications, for example fuel monitoring, mining process liquids monitoring, and pipeline corrosion inhibitor liquid monitoring

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The monitoring is required for two purposes. One purpose is to make sure the liquid does not run out / the tank does not run dry. Another purpose is to ensure the liquid is being drawn from the tank in line with the expected usage, which is another indicator that the process using the liquid is operating correctly, and is a derived measure of the flow from the tank.

Application Detail

For this application, it would be appropriate to use a pressure sensor, and use the pressure from that sensor to determine the level in the tank. The sensor would be most likely strain gauge technology, sometimes called a hydrostatic sensor.

application note industrial tank level monitoring corrosion

These sensors can be either vented or non-vented. Vented sensors have one side of the sensor exposed to the liquid being measured and the other side of the sensor open to the air, either directly exposed, or exposed by using a small vent tube inside the cable with a vent to the atmosphere at the termination end of the cable. Non vented sensors need a barometric pressure sensor at the location of the measurement to provide the current atmospheric pressure, which is then used in a calculation to compensate / normalize the pressure reading based on the current atmospheric pressure at that location and at that time.

application note agricultural water tank monitoring 9

The casing for such sensors can be either stainless steel or titanium. Titanium is chosen for more corrosive environments. The output of such sensors is usually either 0 to 5 volts or 4 – 20 mA however there are some with SDI 12 or Modbus interfaces.

The diagram shows two methods of connecting the sensor. The first method is to immerse the sensor in the liquid and the cable exits from the top of the tank. The second method is to add a T piece to the output pipe, and the pressure sensor then is attached to that T piece to measure the pressure exhibited at the T piece and this pressure is directly related to the level in the tank.

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Some form of communication is required for the telemetry function, either cell phone or satellite. For areas covered by cell phone, this is the most economical choice, and the Neon field units which use cell phone technology is appropriate, either the Neon Metering Module or the Neon Remote Terminal.

If there is no cell phone coverage the Neon Remote Terminal Satellite is another option. As this is a low volume application a small low earth orbit satellite service is sufficient, or perhaps the Neon Remote Terminal Lite which uses the regional beam of the Inmarsat equatorial satellite service could be chosen.

NRT Lite

The application is quite a simple one; the tank level should be measured, perhaps hourly, and stored locally and then sent to the Neon Server daily to display the level on the Neon Web application. The Neon Remote Terminal or Module in the field would also have alarms set up based on any unusual condition, for example too fast level changes would indicate a leak and too slow level changes would indicate a blockage. In the event either of these conditions was detected an immediate transmission back to the server could be initiated and an alarm initiated to alert operators of the problem.
As the power requirements are light, the whole system could be housed inside a small pelican case and powered by a set of lithium batteries. The power budget is small as the sensor would be turned on only for the short time needed to take a measurement every few hours. In this configuration a suitable lithium battery pack could power the entire system for up to 5 years.

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application note industrial tank level monitoring 7

application note Industrial tank level monitoring

Typical Configuration

Options for Application Specific Instruments / InputsUnidata Part NumberDescription
Hydrostatic Water Depth Probe6542D-XPT12 Pressure/Temperature Sensor SDI-12 3.5m, 10m or 20m
Hydrostatic Water Depth Probe - Titanium6542D-X-TTitanium PT12 Pressure/Temperature Sensor SDI-12 3.5m, 10m or 20m
Satellite Telemetry2023ENeon Lite Satellite Terminal
Options for Neon Telemetry - NRT / RTU / Field UnitsUnidata Part NumberDescription
Cellular RTU 3G2013F-AB03Neon Metering Module 3G with Antenna and Li Battery
Cellular RTU 4G2013F-AB04Neon Metering Module 4G with Antenna and Li Battery
Cellular RTU 3G - Industrial2016F-AB03Neon Remote Terminal 3G with Antenna and Li Battery
Cellular RTU 4G - Industrial2016F-AB04Neon Remote Terminal 4G with Antenna and Li Battery
Low Earth Orbit Satellite Globalstar2015E-AB0Neon Remote Terminal - Satellite Globalstar Modem with Antenna and three Li Batteries
Ethernet2017E-0B0-1 or 3NRT Ethernet with single or triple Ethernet Ports
with three Li Batteries
Equatorial Orbit Satellite - Inmarsat2018E-AB0-1 or 3NRT Ethernet with single or triple Ethernet Ports
with three Li Batteries
LCD Display2500ENRT LCD Display
NRT Field Termination Strip2103F2015E,2016F,2017E, and 2018E NRT FTS
NRT Firmware Option2303A-8M8M Extended Memory Option
NRT Firmware Option2303A-8M-CAM8M Extended Memory & Serial Camera Option
NRT Firmware Option2303A-CAMSerial Camera Option
Options for Neon Application Software - Customer ServerUnidata Part NumberDescription
Neon Application Software2302ANeon Server Software Licence Incl 5 NAL
Neon Application Software2302A-10Additional 10 NRT Access Licences
Neon Application Software2302A-20Additional 20 NRT Access Licences
Neon Application Software2302A-50Additional 50 NRT Access Licences
Options for Neon Application Software - Unidata ServerUnidata Part NumberDescription
Neon Application Software2301ANeon Data Initial Subscription Setup Fee
Neon Hosting Service2301A-01Neon Data Service Fee for 1-50 NRTs
Neon Hosting Service2301A-02Neon Data Service Fee for 51-100 NRTs
Neon Hosting Service2301A-10Neon Data Service Fee Metering
Options for Conventional Dataloggers / Field UnitsUnidata Part NumberDescription
Standards Starlogger6004D-11Red Logger 512K with Alkaline Battery
Display Starlogger6004D-21Blue Logger 512K with LCD and Alkaline Battery
Prologger7001D-11Green Logger 1M with LCD and Alkaline Battery
Micrologger8010C-EURMicrologger 512K
Starlogger Field Termination Strip6103E6004D FTS
Prologger Field Termination Strip7100E7001D FTS
Starlog V4 Management Software6308A-AUEStarlog V4 Full Licence Key