Ultraflux UF841 EXD Ultrasonic clamp-on flow meter for hazardous areas

The UF841-EXD is one of the most advanced ultrasonic clamp-on flow meters for hazardous areas available globally. The UF841-EXD incorporates all the intelligence, innovation and experience acquired by Ultraflux in 40 years of being the world’s specialists and technical experts in ultrasonic transit time measurements.

Features and benefits

Suitable for pressurised pipes containing natural gas, compressed air and liquids, this bi-directional ultrasonic clamp-on flow meter can be used for a wide range of applications in hazardous areas and is perfect for measuring flow in the chemical, petrochemical, coal seam gas, oil and gas industries.


Ability to measure almost every pipe diameter. This ultrasonic clamp-on flow meter for hazardous areas has probes to measure from 10mm OD to 10000mm OD. The clamp-on probes are suitable for all metallic and plastic pipes and multi-layered pipes. In-line, wetted probes may be used for more challenging applications.


The external clamp on probes (without any contact with the liquid) enable quick, easy and low cost installation. The integrity of the pipe is not jeopardised and flow is not disrupted by a shut-down. There are no moving parts so maintenance is not an issue.  With no intrusion into the pipe, there are no pressure drops or turbulence.


Four chord input enables this converter to receive signals simultaneously from four sets of probes.  These can be attached to  the same pipe or different pipes.  It may be useful in a challenging application to install four or more sensors on the same pipe to obtain an accurate result. The ability to monitor four separate pipelines simultaneously with one ultrasonic clamp-on flow meter is extremely convenient with cost and set up time efficiencies.


Unrivaled accuracy and versatility with performance accuracy up to 0.5%, measurement resolution less than 0.1 nano second and suitable flow range from 1 mm to 45 metres per second.


Certified for use in hazardous areas with ATEX approval for use in Zone 1, 2, 21, 22 and class 1 and 2 (Division 1 or 2).


Ability to operate with low voltage, this ultrasonic clamp-on flow meter for hazardous areas can be powered on 10 – 32 Volts DC or 110 to 240 Volts AC.


Surge protection to protect the electronics from an increase in power supply. Over voltage protection in accordance with EN 61000-4-5.


Connectivity with current, voltage, contact and temperature inputs. Current, voltage, relay and pulsed outputs and an RS232 or RS485 serial link with standard JBUS (MODBUS) protocol. This ultrasonic clamp-on flow meter for hazardous areas is perfect for integration with instrument control panels and telemetry systems.


Signal quality index using echo visualisation to verify the signal quality from each chord and identify any distortions caused by electrical noise or air bubbles. The outcome of corrective actions are also verified providing the operator with the knowledge the problem has been solved.


Status indicator LED’s on the front panel enable the operator to quickly evaluate the current status or nature of a problem.


Ex rated enclosure with a high ingress protection rating of IP67 ensures this ultrasonic clamp-on flow meter is suitable for use in hazardous areas. The back-lit display, keypad and mounting bracket facilitate quick and easy installation and set up.


Internal data logger with a massive memory storing 530,000 time and date stamped readings.  This equals over 12 months data at 1 minute logging intervals. The logging interval is user programmable from 1 second to 24 hours.  The logger can store a wide range of parameters including min flow, max flow, average flow, velocity, totalised flow, delta, gain and status. It provides an extensive summary of the flow conditions allowing the operator confidence in the data. With the choice of “cyclic” or “stop when the memory is full”, this ultrasonic clamp-on flow meter for hazardous areas is perfect for storing data that can be retrieved for incident investigation.




  • Calorific value calculation.
  • Measurement of liquid flows in water, raw water, waste water, ultra-pure water, non-conductive water, oil, chemicals, refined and raw petroleum products.
  • Measurement of natural gas and compressed air flow.
  • Suitable for different pipes (steel, stainless steel, asbestos cement, cast iron and carbon fibre).
  • Gas distribution network.
  • Fire main monitoring.
  • Flow measurement for acids and chlorides.