Choosing the Right Tank Level Instrumentation: Dragino Ultrasonic vs Pressure Transmitters
A tank level system only works well when the instrument matches the tank, the liquid, and the site. A device that looks right on paper can give poor readings if the tank is too tall, the surface foams, the roof has no clear mounting point, or the power supply is limited.
For many sites, the choice comes down to two strong options: Dragino ultrasonic level devices or pressure and level transmitters connected through analogue inputs. Both can be supplied as complete instrument packages through ProSense Instruments, with the sensor, communications, power, and installation hardware selected together rather than treated as separate parts.
Start with the tank before choosing the technology
The best level instrument is rarely chosen from a feature list. It starts with the physical application.
A clear selection should answer these questions:
What is the tank height and measuring range?
What liquid is stored?
Is the tank vented, sealed, pressurised, or open to atmosphere?
Can the instrument mount on top, on the side, or at the bottom?
Is mains power available, or does the site need battery or solar power?
Should readings go to LoRaWAN, cellular, Modbus, a local display, or a control system?
How easy is it to access the tank for installation and maintenance?
Dragino ultrasonic devices and pressure-based systems solve the same problem in different ways. Ultrasonic measures distance from above the liquid. Pressure transmitters measure liquid head from below or from a wetted point in the tank.
That difference affects almost every decision that follows.
When Dragino ultrasonic devices are the better fit
Dragino ultrasonic devices are a strong choice when the application suits non-contact measurement. They are typically mounted at the top of the tank and measure the distance down to the liquid surface. The system then converts that distance into level, volume, or percentage depending on the setup.
This approach works well for many water, wastewater, chemical, and utility tanks where the liquid surface is reasonably open and the sensor has a clear path.
Tank height matters for ultrasonic level
Ultrasonic level measurement needs the distance from the sensor to the liquid surface to stay within the device’s working range. The sensor also needs a dead band near the face, where it cannot measure accurately.
For short and medium-height tanks, a suitable Dragino ultrasonic unit can be a clean and efficient option. Taller tanks need more checking. The height, expected empty level, top mounting point, and any internal structures all affect signal quality.
A practical selection should allow for:
The maximum distance at lowest level
The minimum distance at highest level
Any raised mounting boss or nozzle
The shape of the roof
Obstructions such as ladders, mixers, pipes, or bracing
If the sensor will look straight down at a calm surface, ultrasonic measurement is often simple. If it must look past pipework, an angled roof, or a narrow stilling tube, pressure measurement may be safer.
Liquid condition can make or break ultrasonic readings
Ultrasonic sensors need a clear echo from the surface. They do not touch the liquid, which is useful for corrosive or dirty products, but the sound pulse still has to travel through the air space above the liquid.
Ultrasonic is usually suitable for:
Clean water
Rainwater harvesting tanks
Many chemical storage tanks
Wastewater tanks with open liquid surface
Diesel and other non-foaming fluids, subject to compatibility and area requirements
It can be less suitable where there is:
Heavy foam
Thick vapour
Turbulence under the sensor
Rapid filling with splashing
Condensation on the sensor face
Internal agitators
Narrow, irregular, or obstructed tank openings
Foam is a common problem. A foamy surface may absorb or scatter the ultrasonic pulse. Vapour can also affect readings, especially when temperature changes quickly above the liquid.
In those cases, a pressure transmitter often gives a more stable level signal because it measures the weight of liquid above the sensing point.
Mounting is simple when the top of the tank is accessible
A Dragino ultrasonic package suits sites where the top of the tank is easy to reach and a clear mounting point exists. Typical work includes fitting a bracket, threaded connection, or tank top mount, then aiming the sensor down toward the liquid.
Good ultrasonic mounting practice includes:
Mounting the sensor vertically
Keeping it away from fill streams
Avoiding internal obstructions
Leaving enough clearance from tank walls
Protecting the sensor from impact and weather
Using a stilling arrangement only when it suits the device and application
For remote or outdoor tanks, this clean top-mounted arrangement can reduce the need for wetted fittings. It also avoids drilling low on the tank, which can be a major benefit on existing installations.
When pressure and level transmitters are the better fit
Pressure and level transmitters measure the hydrostatic pressure created by the liquid column. In simple terms, more liquid above the sensor means more pressure.
These systems usually connect to an analogue input, commonly a 4 to 20 mA input, on a logger, remote telemetry unit, PLC, display, or IoT device. ProSense Instruments can package the transmitter with the analogue input device, power supply, enclosure, cabling, and communications hardware needed for the site.
Pressure-based level measurement is often the right choice when the surface is difficult, the tank is tall, or the mounting point at the top is poor.
Pressure transmitters handle difficult liquid surfaces
A pressure transmitter does not care if the tank surface is dark, reflective, foamy, or turbulent. The device reads the liquid head at the installation point.
That makes it useful for:
Tanks with foam
Tanks with vapour or condensation
Deep tanks where top distance is too great
Tanks with internal obstructions
Sumps and wet wells
Underground tanks
Tanks where top access is unsafe or unavailable
There are two common physical arrangements.
Submersible level transmitters are lowered into the tank, often suspended by their cable. They are common in water tanks, boreholes, wastewater wells, and sumps.
Externally mounted pressure transmitters connect to a tapping near the bottom of a tank or pipework. They suit tanks with an available process connection and applications where the sensor can be isolated for service.
Both need material compatibility with the liquid. Wetted parts, seals, cable materials, and process connections must match the product in the tank.
Density affects pressure-based level readings
Pressure level measurement depends on liquid density. Water is straightforward. Oils, chemicals, brines, and process liquids may need closer checking.
If the liquid density stays consistent, pressure measurement can be very accurate and repeatable. If density changes with concentration or temperature, the level reading can shift even when the actual height stays the same.
For many storage applications, this is not a problem. For process applications with changing density, the package should be specified with care.
Analogue inputs make pressure systems flexible
A pressure or level transmitter with an analogue signal can connect to many types of equipment. That is one reason these systems remain widely used.
The analogue input can feed:
A local level display
A data logger
A PLC or control panel
A pump controller
A remote telemetry unit
A LoRaWAN or cellular input device
An alarm relay module
This flexibility is useful when a tank level signal must be part of a wider control system. For example, a clean water tank may need a local display for operators, high and low level alarms, and remote readings for maintenance staff. A pressure transmitter with the right input package can support that type of setup.
A practical comparison by application factor
The table below gives a working comparison. It is not a substitute for checking each tank, but it helps narrow the choice quickly.
Application factor | Dragino ultrasonic device | Pressure or level transmitter with analogue input |
Tank height | Best where the full measuring distance is comfortably inside the ultrasonic range | Well suited to deeper tanks when the pressure range is selected correctly |
Liquid surface | Works best with a clear, calm surface | Handles foam, turbulence, vapour, and poor surface conditions better |
Liquid contact | Non-contact, useful for dirty or corrosive liquids | Wetted sensor or process connection must be compatible |
Mounting | Top-mounted with clear vertical path | Submersible, side-mounted, or bottom connection |
Existing tanks | Good when top access is easy and no low tapping exists | Good when top access is poor or a bottom connection already exists |
Power | Often suited to low-power remote monitoring packages | Depends on transmitter, analogue input, and communications device |
Communications | Commonly used in wireless remote monitoring packages | Very flexible through analogue input modules and telemetry hardware |
Installation risk | Avoids opening the tank below liquid level | May need wetted installation or isolation fittings |
Maintenance | Sensor face may need checking for condensation or build-up | Wetted parts may need cleaning or inspection depending on liquid |
Best fit | Remote tanks with clean top access and suitable surface | Difficult liquids, deep tanks, sumps, and control system integration |
Power and communications should be selected as part of the package
Level measurement is only useful if the reading gets where it needs to go. That is why a complete instrument package is often a better route than buying a sensor first and solving power and communications later.
For remote tanks, Dragino devices are often considered because they suit low-power wireless monitoring. Depending on the model and site, the package may use battery power, external DC power, or solar support. Communications may include LoRaWAN or other wireless options, depending on the network available.
Pressure transmitter systems also work well in remote setups, but they usually need a transmitter supply and an analogue input device. The input device can then send the level reading through LoRaWAN, cellular, or a site network.
The choice should be based on site conditions rather than preference.
Choose LoRaWAN when a network is available
LoRaWAN suits many tank monitoring applications because it can send small packets of data over long distances with low power use. It is a good fit where readings are needed every few minutes or a few times per day, rather than every second.
A LoRaWAN package needs:
A suitable gateway or coverage from an existing network
Correct antenna placement
A sensible reporting interval
Battery calculations based on expected use
Signal testing at the tank location
Choose wired analogue when control is local
If the tank connects to a control panel, pump station, or PLC, a wired analogue signal may be the best option. It gives a continuous signal and fits common industrial control practice.
A wired package may include:
Pressure or level transmitter
4 to 20 mA input
Local indicator
Surge protection
Power supply
Enclosure
Cable glands and terminals
Alarm outputs where needed
This arrangement is often preferred for pump control, dosing systems, process tanks, and sites where operators need a local display.
Installation details have a direct effect on reliability
A good sensor can perform badly if installation details are rushed. Complete packages from ProSense Instruments should be selected with these physical details in mind.
For Dragino ultrasonic installations
Check the sensor position before drilling or fabricating brackets. The device needs a clear path to the liquid, not just a convenient place to mount.
Good practice includes:
Keep away from fill points
Avoid sidewall echoes
Mount level and vertical
Allow space for maintenance access
Protect cable entries from water ingress
Use suitable weather protection outdoors
Confirm the empty and full distances during setup
If the tank is plastic, consider how the sensor bracket will be supported. If the tank is metal, consider earthing, lightning exposure, and cable routing. For outdoor sites, antenna position can matter as much as sensor position.
For pressure transmitter installations
The main concerns are liquid compatibility, pressure range, venting, and mechanical protection.
For submersible transmitters, check:
Cable support and strain relief
Protection from pumps or mixers
Sludge build-up at the bottom
Vent tube protection where used
Safe retrieval for maintenance
For externally mounted transmitters, check:
Process connection type
Isolation valve arrangement
Risk of blockage
Freezing risk on exposed pipework
Access for calibration or replacement
Overpressure protection if the tank can be pressurised
Hydrostatic transmitters need the correct reference. Vented tanks usually use gauge pressure measurement. Sealed or pressurised tanks may need a different arrangement, such as differential pressure or compensation.
How to decide between the two
The decision becomes much easier when each application factor points in the same direction.
Choose a Dragino ultrasonic package when:
The tank has safe and easy top access
The liquid surface is usually calm and exposed
Non-contact measurement is preferred
The tank height fits the device range with margin
Wireless remote monitoring is the main goal
There are no major internal obstructions
The installation should avoid wetted fittings
Choose a pressure or level transmitter package with analogue input when:
The tank is deep, underground, or hard to measure from above
Foam, vapour, turbulence, or condensation is likely
A local controller or PLC needs a standard signal
A bottom or side process connection already exists
The liquid density is known and stable enough
The site needs alarms, displays, or pump control
A submersible sensor is practical
There are also cases where both options can work. For a clean water storage tank with a flat roof and calm surface, ultrasonic may be neat and cost-effective. The same tank connected to a pump control panel may suit a 4 to 20 mA level transmitter better. The right answer comes from the full package, not the sensor alone.
What a complete ProSense Instruments package should include
A complete tank level package brings the measurement method, power system, communications, and fittings together. That reduces mismatched parts and makes installation easier to plan.
For a Dragino ultrasonic package, the scope may include:
Suitable Dragino ultrasonic level or distance device
Mounting bracket or tank fitting
Antenna and communications accessories
Battery, external DC, or solar power arrangement where suitable
Gateway or network guidance where required
Configuration support for level, distance, or volume reporting
For a pressure transmitter package, the scope may include:
Submersible or process-mounted level transmitter
Correct pressure range and wetted materials
Analogue input module
Power supply or battery-supported telemetry device
Local display or alarm module if needed
Weatherproof enclosure
Cable, glands, fittings, and protection accessories
This package approach is especially useful when multiple tanks are involved. It keeps sensor type, signal format, and communications consistent across the site while still allowing each tank to use the most suitable measuring method.
The takeaway
Dragino ultrasonic devices are often the cleaner choice for non-contact, top-mounted remote tank monitoring, especially when the tank has a clear measuring path and a manageable height. Pressure and level transmitters connected through analogue inputs are often the stronger choice for difficult surfaces, deeper tanks, sump applications, and integration with control systems.
The best result comes from selecting the full instrument package around the application. Start with the tank height, liquid, mounting point, power source, communications path, and installation constraints. Once those are clear, the right technology usually reveals itself.
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