Choosing a Water Level Logger – What you need to know

One of the first questions raised when selecting a ground water data logger is Vented or Non – vented, also called gauge or absolute. To fully understand which will be best for your application, first we must explain the differences between the two technologies.

Non Vented Water Level Data logger

A non-vented data logger utilises an absolute pressure sensor that measures the pressure of everything above it, this commonly is the water as well as the barometric pressure being exerted by the atmosphere on the pressure sensor. Therefore to achieve accurate water level measurement, the water level data recorded by this type of instrument must be adjusted for barometric effects. The image below shows a typical setup

Vented Water Level Data Logger

A vented data logger operates with a vent tube from the surface, allowing for continuous barometric pressure to exert back pressure on the transducer, removing atmospheric influences from the measurements.  When selecting this type of data logger you must ensure the integrity of the vented cable.

So which type should I use?

Below we have compiled a list of the key factors and application details to consider, before making your decision.

Number of monitoring locations

If you application is to monitor only one well, then typically vented logger could be more cost effective and more simple to use, as an additional barometric sensor would not be required.  If a series of wells / locations are being monitored and all wells are located in the same 20 km area, then a non-vented solution would be your best option, as a non-vented sensor is typical more cost effective and you can deploy a barometric sensor centrally and use that data to compensate all your collected data.

Depth of Well

Vented water level loggers are a good selection for large / shallow. Typically this types of application responds immediately to barometric pressure changes.  When monitoring deeper wells a better selection would be a non-vented logger as barometric influences are much less and you have a wide range compensation options.

What Data is being collected?

For pump tests or slug tests, both types of logger would work very well.  Generally these tests are of short time period, so no significant barometric change should occur during the sampling periods so barometric compensation of the data is not essential, but can be used if required.

For long term monitoring where barometric changes would vary, you should choose the type of logger you need based on other relevant factors, including a solution for barometric pressure compensation.

Monitoring location conditions

Vented water level loggers incorporate a vent tube, which is open to the atmospheric pressure. This tube is typically sealed with a water impermeable barrier and includes desiccant. If this is not properly maintained a potential issue can be water intrusion.  Water intrusion will not only effect water level readings been taken by the sensor, it will also cause the battery to drain quickly and cause problems with the electronics, making your data irrecoverable.

Our advice would be if you know your loggers will be used in a highly humid area or location prone to flooding, you should ALWAYS select a non-vented solution.

Type of Aquifer

Confined aquifers have an instant reaction to barometric pressure changes, while non-confined aquifers generally have a delayed reaction.  If using a vented logger in a non-confined aquifer it is not able to recognize or adjust for the delayed response in your data.

Location considerations

The final consideration will be the monitoring site. If this is in a remote / inaccessible area, we would recommend you choose the non-vented loggers.  A non-vented water level logger will require little maintenance and can be deployed for long periods of monitoring without human intervention.  Vented loggers are more inconvenient to transport as the vented cables than their non-vented alternative.

We hope the above information proves helpful in aiding with your water level logger selection. If you do require any further information please feel free to contact us on and we will be happy to help.

DipperLog Nano – New Affordable Water Level Logger

Bell Flow Systems are proud to introduce the Cost effective DipperLog NANO water level logger to our ground water measurement range. The DipperLog NANO sensor is a cost effective solution, costing only £299. The sensor is ideal for people looking to monitor water level applications in ground water, estuarine and surface water applications.

The DipperLog NANO is available in two versions – the DipperLog Nano and the vented DipperLog Nano. The standard model is an absolute (non-vented) level sensor which can be deployed with either Stainless Steel wire, or with direct read cable if you require surface data collection. For long term monitoring applications a Barlog NANO will be required for barometric compensation. The Vented Dipperlog Nano can be specified with vented cable for data collection from the surface, without needing to retrieve the sensor.

A fast logging interval means that readings can be collected as fast as 1 reading per second. Battery life for the device is up to 7 years with an internal data logger offering collection of 32,000 data sets.

Programming of the ground water logger can be achieved using simple PC software, while data from the device can be collected by third party datalogger or telemetry systems using the on-board SDI-12 or RS232 protocols. For more information on the DipperLog Nano and accessories please visit our website, or contact the Bell Flow Systems Sales team

Leveline EWS system provides a cost effective Level measurement solution

Bell Flow Systems are pleased to introduce the new Leveline early warning system (EWS) to our range. The EWS system is a package comprising of a battery powered telemetry device which is paired with a Leveline mini sensor to provide remote access to water level data information.

Data from the EWS system can either be viewed by SMS text message, where a text sent to the device will provide a response text with the specified parameters such as: level, temperature, rate increase, alarm status and the battery power of the device. Also the unit can transmit data daily via email in excel (.csv) format allowing the user to then review and analyse the daily recorded information.

The EWS also provides an alarm output option, enabling the user to pre-configure alarm settings within the device to send urgent data via email or SMS. Examples of this might include high level or low level alarms in the case of flood monitoring.

A major advantage of the EWS is that, unlike competing devices, there is no requirement for annual subscription fees, reducing ongoing costs of ownership. All that is needed is the insertion of an active SIM card to operate the device. A further advantage is that all data is owned and collected by the owner, not stored on a server operated by another company.

The design of the EWS also means it is flexible across a variety of application areas, including – Flood Monitoring, Ground Water Monitoring, Surface water monitoring, Tank level monitoring,Well Monitoring and Remote Level measurement application

Configuration of the device is achieved primarily through a mobile phone, making setup quick and simple, also reducing purchase costs since the unit does not require software or a communications cable to connect to it.

DXN Ultrasonic Flowmeter goes wireless!

Bell Flow Systems were recently pleased to support a new client on the delivery of an advanced wireless flow and energy measurement project.

The application criteria was clear, the client wanted to be able to use an ultrasonic flow meter as a portable stand-alone unit, but occasionally for remote applications they needed to be able to leave the flow meter installed on site, with access to the systems data maintained remotely.  The application involved energy audit tasks, so a model with thermal energy integration was specified.

For the flow meter, Bell Flow Systems selected the Badger Meter- DXN ultrasonic flow meter. This meter is a hybrid device capable of both transit time and Doppler flow measurement. On this occasion the heat meter option was provided which facilitates thermal heat energy measurement.

To ensure that the equipment supplied could be used as a hand-held unit, connection to the DXN meter had to be simple and lightweight. For this reason, single cable Ethernet over I/P connectivity was chosen for the DXN and to this our UG1005 logging telemetry system was connected. Via this communication protocol, information including: Flow rate, Supply and Return Temperatures and signal strength could be collected from the DXN to provide all of the results and diagnostic information in real time, with data recorded every minute.

For further information on the DXN model and the remote data collection options, Bell Flow Systems can be contacted at –

BLFT liquid flow turbine gets saucy!

Bell Flow Systems were recently approached by a well-known curry sauce producer from the UK to provide accurate and repeatable batch-control systems for measuring the water volumes used in their supermarket sauce recipes.

The client’s requirements meant that the system would be used for a variety of different recipes, so the batch controller had to be easy to use and able to be reprogrammed for varying volumes.

For this application Bell Flow Systems selected the BLFT stainless steel turbine flow meter, combined with a Fluidwell- F130 batch controller. A fast acting solenoid valve was also incorporated into the process so that dispensed volumes could be quickly controlled, providing the highest level of accuracy and performance.

The F130 LCD Batch controller was connected to the signal output from the BLFT to provide the operator with a volumetric countdown on-screen of the required batch volume. Internal control relays actuated the solenoid valve once the desired batch volume had been met, utilising automatic over-run compensation to achieve repeatability.

Initially a single system was provided to the customer, however after successful performance testing, a further two systems were provided so that the operators on neighbpuring production lines could automate their batch processes too.

For further information on the BLFT and F130 batch controller contact Bell Flow Systems –

New Leveline-CTD added to environmental range

Bell Flow Systems are pleased to introduce the Aquaread LeveLine-CTD For the measurement of level, conductivity and temperature.


The LeveLine-CTD is manufactured from titanium and can be used for long term deployment in the harshest of environmental applications. The sensor offers high levels of accuracy, and a large 500,000 data point memory, alternatively the sensor can be connected to a third party data-logger or recording systems via optional SDI12/RS485 output. The Leveline-CTD offers Absolute or Gauge variants, which are available to cover applications from groundwater to surface water.

The LeveLine-CTD is perfectly suited to the measurement of level and conductivity in the following applications: Saline intrusion monitoring, Contaminant plume remediation Studies, Landfill Leachate monitoring mine, Agricultural / storm water runoff monitoring and Tracer tests.

Contact Bell Flow Systems for further information or visit the website here for further information on this product.

Introduction to non-contact water level measurement

Types of non-contact Level measurement available

When considering the use of a non-contact sensor for water level measurement applications, two technologies are currently prominent and readily available in the market place – Ultrasonic and Radar. Both technologies have their advantages and disadvantages, which we will outline below.

Firstly we will explain how Ultrasonic technology works…

Ultrasonic non-contact level measurement

Ultrasonic measurement sensors are mounted above the water (open channel applications) or on top of the tank (contained applications). Measurement Principle: The Sensor head emits an ultrasonic pulsed sound signal towards the liquid being measured, which then bounces back like an echo from the surface of the media. The sensor head then calculates the time elapsed between pulse emission and reception (Time of Flight) using filtering algorithms to generate a measurement which is proportionate to the level measurement in the channel, tank or silo. This happens many times every second to provide continuous and accurate level measurements.


Ultrasonic level transmitters are generally lower cost when compared with a comparable radar solution. They are easy to install and program as many models feature an integral or removable display which allows the sensor to be set up whilst installed on a tank or above the open channel. With most models it is also possible to program in tank or channel shape data-points for enhanced volume calculations.

These devices are non-contacting so are not susceptible to fouling, greatly reducing maintenance when compared with a traditional contacting sensor alternative. Being a non-contact solution also means that the sensor is not susceptible to any changes in the characteristics of the fluid. However changes in air temperature will usually occur, so the on-board temperature measurement and compensation found in most models will ensure that the sensor adjusts it’s measurement for a change in the sound speed of air to ensure that accuracy levels are maintained


If used in the correct application the disadvantages of ultrasonic are few. However there are applications where ultrasonic level performance can be compromised. They always need a medium and cannot propagate through Vacuum, which is a disadvantage of using Ultrasonic Transmitters for Level measurements on Vessels that operate on very low pressures. Also, sound waves are prone to attenuation depending on the medium. Whereas, Radar sensors use Electromagnetic waves which possess a Field of Energy which makes them travel through Vacuum, even without a medium.

The following conditions are examples of problematic applications for ultrasonic level measurement

-Heavy Vapours



-Obstructions in the signal path

-Temperature effects from Direct Sunlight

For applications where heavy vapours, steam or foam are present we would advise the use of a radar sensor over ultrasonic technologies. Please see the Radar section below.

As the ultrasonic principle relies on clean transmission and collection of the signal, anything which could potentially affect its’ path could compromise the measurement and then cause inaccuracies.

Although these situations are problematic it does not mean that they preclude the use of this technology. As an example the patented echo profile technology in our range allows for obstructions in the measurement path to be ignored as a false echo.

Another potentially negative effect on the ultrasonic principle is the exposure of the sensor to direct sunlight. Most ultrasonic transmitters and sensors have a built-in temperature sensor for air sound-speed compensation and if the ultrasonic sensor is exposed to direct sunlight this can cause the sensor to become warmer than the ambient air around the sensor. This in turn can lead to the sensor incorrectly compensating for air temperature and inaccuracies to occur in the level measurement


Radar non-contact level measurement

Radar measurement sensors are mounted above the water (open channel applications) or on top of the tank (contained applications). Measurement Principle: Radar, by contrast to Ultrasonic, works not with sound waves, but with electromagnetic waves. This is the key difference. Like ultrasonic types, the waves bounce off of objects and travel at a known speed (much faster than ultrasonic waves), but they react differently to certain materials. There is a different set of variables that affects how well a radar sensor operates.


Radar sensors have a shorter dead band than their Ultrasonic equivalents ­(a minimum distance they have to be sited above the liquids surface.) They are also higher precision than ultrasonic models.

Unlike ultrasonic sensors, radar is much less affected by temperature, improving consistency and accuracy. Radar is also well suited for specialty applications, such as working in a vacuum, or in higher pressures (as long as the housing can handle it). Radar sensors trump ultrasonic as soon as foam, vapours, powder, dust, or uneven surfaces are introduced to the measurement environment equation, although perfect operation is not guaranteed.

They are easy to install and program as many models feature an integral or removable display which allows the sensor to be set up whilst installed on a tank or above the open channel. With most models it is also possible to program in tank or channel shape data-points for enhanced volume calculations.

These devices are non-contacting so are not susceptible to fouling, greatly reducing maintenance when compared with a traditional contacting sensor alternative. Being a non-contact solution also means that the sensor is not susceptible to any changes in the characteristics of the fluid.


In general, radar transmitters are more expensive (but can handle more difficult applications), tend to have longer maximum ranges, and often have wider beam angles than ultrasonic transmitters. If used in the correct application the disadvantages of ultrasonic are few. However there are applications where ultrasonic level performance can be compromised.

The following conditions are examples of problematic applications for Radar level measurement

-Domed top tanks – some radars can’t take mounting in the centre of a domed top – the parabolic effect of the dome gives them problems.

-Foam and turbulence of the media can present challenges for both technologies, especially ultrasonic (guided-wave radar may be a good choice in such cases).

-Radar’s main limitation is found in the dielectric of the material it is measuring. Low dielectrics (good insulators, poor conductors like hydrocarbons) can be problematic for radar.

-Temperature effects from Direct Sunlight (although not as significant as Ultrasonic)

-Radar models are still higher cost than directly equivalent Ultrasonic models, although the prices are coming down as the popularity of this technology and its inherent benefits rises.

Blancett B3100 flow monitor

The new Blancett B3100 flow monitor incorporates advanced options with user-friendly full operation through the glass. Data logging, remote data access, and programming are available without opening the enclosure. The programming software allows for easy remote configuration.

B3100 LCD Flow Monitor

The B3100 flow monitor processes a frequency output from a flow meter, to calculate flow rate and accumulated total. The B3100 also has a 16-point linearization of the flow curve (with interpolation) for improved accuracy.

The B3100 is explosion-proof in accordance with ATEX, IECEx, FM and CSA c-us. A rugged one-inch NPT thread is provided for direct flow meter mounting. The flow monitor’s large backlit LED display shows flow rate, total, measuring units and a flow rate-indicating speedometer, with hourly flow totals and settings which are logged in an archive. Each log contains flow rate, flow total, accumulated total, time & date stamp and log number. Logged data can be viewed through the display, or via Modbus RTU Communications or free PC software options. Interval logs are available by minute or hourly increments, with daily and event logs also provided. The flow monitor’s user-friendly programming software enables log data to be downloaded as a .csv file.

The B3100’s remote programming facility is a key product feature, which allows for full configuration of the flow monitor. Software automatically detects the monitor and downloads its data. Configurations for multiple units can be saved on a PC, and configuration data can be changed and easily uploaded back to the monitor.


Built to last…. IRON-75 Fuel Transfer Pump

Built to last…. IRON-75 Fuel Transfer Pump from European manufacturer Gespasa. 

High quality self-priming, 75 Litres/min diesel pump available from Bell Flow Systems. 

Buy on-line here  IRON-75

  • Self-priming. Eccentric self-adjusting blades
  • With re-circulation bypass
  • ATEX models available here>>: 
  • Suction: 5m · Delivery: 30m
  • Free flow: 75 l/min
  • Consumption: 1.9-4.5 Amps
  • Motor: 0.5 kW 230 VAC self-ventilated 50/60 Hz single phase with thermal cut-out protection
  • S1 Continuous duty
  • IP-55 Protection
  • 3000 rpm
  • Connection through 1″(BSP) threads and flange option
  • It has built-in steel filter of 350 µm (micron).
  • ON/OFF luminous switch with IP-55 protection
  • 3m electric cable 
  • Anti-corrosion treatment

Also available as a wall-mount or drum-mount fuel transfer kit :


New Cost-effective Wireless Rain Gauge

Bell Flow Systems are pleased to introduce the ARG100 rain gauge into their range of environmental measurement products.

The ARG100 is a cost effective solution for precipitation measurement. The aerodynamic design ensure that the sensor does not interfere with the surrounding airflow ensuring that accurate measurement of precipitation is continuously achieved. The U.V resistant materials ensure robustness in the field to maintain a high level of measurement accuracy. In standard form the rain gauge is offered with a 0.20mm per tip pulse output, however additional options are available.

Measurement of rainfall is achieved using a traditional “tipping bucket” mechanism which has been proven as a reliable industry and scientific standard for the measurement of precipitation for many years. Each tip of the bucket provides a contact closure of a reed switch to create an output from the rain gauge.

The output from the ARG100 can easily be connected directly to our OM-CPPULSE101 for local data collection. The data received from the ARG100 can be calibrated to ensure that collected data is converted to represent accurate rainfall information. If however remote data collection is required our Aqualink II which offers GSM / GPRS collection, can provide data remotely to a PC, tablet or mobile phone. No software is required to view the data, only a web enabled device, where you can log onto to your personal device dashboard via a username and password.