Marine Fire

Welcome to Coltraco Ultrasonics’ range of portable Liquid Level Indicators specifically for the marine environment. 

We pride ourselves in our UK made, high-quality, reliable, and accurate instrumentation designed for ship owners, servicing companies, marine surveyors, and crew to inspect fire suppression systems such as CO2, FM-200™, NOVEC™ 1230, Halons and a wide variety of other clean agents.  

We have been developing non-invasive level detection technology for over 30 years and are proud leaders in this field. 

Why choose Coltraco Ultrasonics’ range of Ultrasonic Liquid Level Indicators?

Better: Using ultrasonic technology to check the contents of your fire suppression cylinders is non-invasive, non-destructive and non-disruptive meaning it is safer for personal and does not require the user to shut down the fire suppression system during inspection. The use of ultrasonic technology is a regulatory approved alternative method for monitoring the contents of cylinders. Our range of ultrasonic liquid level indicators are accurate to ±1.5 mm.   

Faster: The non-disruptive, non-invasive nature of ultrasound contents monitoring allows testing to take place when the fire suppression cylinders are in-situ and operational. This process takes around 30-seconds per cylinder using our easy-to-use, intuitive technology. Compare this to traditional, manual weighing which requires lifting equipment, multiple people and around 15-minutes for inspection.  

Cheaper; Enabling inspection to take place without disruption your cylinder installation means no shut-down, saving time and no requirement for multiple operators, saving labour costs. We have a large range of level monitoring technology allowing us to be competitive with pricing and Coltraco Ultrasonics have a “Price Promise” to be the most competitive on the market.  


Marine Fire Systems 

 Coltraco Ultrasonics have over 30 years of experience proudly operating across the maritime industry alongside ship owners, ship managers, marine surveyors, port authorities, shipyards and classification societies. As of 2021, over 20% of the world’s ocean-going vessels use our technology on board. Fire remains the second principal reason for the loss of ships at sea, primarily due to inadequate, or poorly maintained fire suppression systems.  

Marine fire suppression systems consist of a group of banked fire cylinders, which are typically high-pressure CO2 and are integral for protecting vital infrastructure, people and assets from damage due to fire. Fire suppression systems are used to extinguish, control and prevent fires from spreading. The majority of fires onboard marine vessels begin in the engine room, where machinery is operating under pressure and at high temperatures.   

Although most marine fire suppression systems contain CO2, we specialise in the monitoring of all types of liquified fire suppression agents, such as CO2, FM-200™, NOVEC™ 1230 (clean agents) and Halons.   

“Protecting your marine operations from devastation due to fire at sea”  

In the event a fire is detected the centralised monitoring system located in the control room, or bridge will trigger the alert system which activates the fire suppression system. The cylinder valves are opened, and the pressure of the cylinders drive the agent through a pipe network to be discharged at the point of fire. In some cases, these systems are supported by ancillary nitrogen cylinders if the distance the agent needs to travel is great.  

Marine fire systems, like all safety-critical infrastructure, is regulated. Chapter 5 in the IMO SOLAS FSS Code which details how vessels’ fire extinguishing systems should be checked for leaks states that the crew onboard ship are not qualified to undertake CO2 servicing as it requires the dismantling, weighing and re-installation of the complete system, which must be done by a licensed organisation when the ship is in port. The code states that; “means shall be provided for the crew to safely check the quantity of the fire extinguishing medium in the containers.” To implement the IMO SOLAS FSS code, portable liquid level indicators such as our marine variant Portalevel™ range can be used on-board, allowing the crew to meet the IMO SOLAS code while underway between servicing schedules.

Ultrasound & Ultrasonic Liquid Level Operating Principle 

All of our liquid level indicators use ultrasonic sensors to identify the contents of fire suppression cylinders. Ultrasonic sensor technology or Ultrasonic Testing (UT) is a reliable, versatile and safe method for Non-Destructive-Testing (NDT). Ultrasonic waves are sound waves with frequencies above the upper limit of human hearing (above 20 kHz, or 20,000 Hz). Sound waves are mechanical waves that travel in a straight line and require a medium through which to travel. The propagation and attenuation of sound waves depend on the structure of the medium down to an atomic level; therefore, ultrasound is a useful method of studying a material’s structure and the processes occurring within it. 

Whilst the highest frequency a human can hear is around 20,000 Hz, Our Portalevel® units are high-frequency ultrasound transmitters that use sound at a frequency of 1,000,000 Hz or 1 MHz. To do this, the main unit sends a strong electrical signal to the sensor (a piezoelectric crystal), which then emits a high energy pulse of ultrasound into the fire cylinder wall through what is known as the reverse piezoelectric effect.  

The term ‘piezoelectricity’ has its roots in the Greek word ‘piezein’ (to press) and was discovered in 1880 by Pierre and Paul-Jacques Curie. Piezoelectricity is the appearance of an electrical potential across a crystal when it is subjected to mechanical stress and is a reversible effect. A crystal that exhibits this effect by becoming charged when it is compressed, or distorted is a piezoelectric crystal. Similarly, passing electricity through a piezoelectric crystal causes the crystal to vibrate back and forth (producing ultrasound); this is the reverse piezoelectric effect. 

The ultrasound that is produced is conducted through the solid walls of the container and then interacts with the contents (CO2, FM™-200, NOVEC™1230, etc.). After the sensor, also known as an ultrasound transducer, stops emitting ultrasound, it starts listening for the returning echoes of the signal. It sends these signals back to the main electronic unit, which then analyses the returning signal in comparison to the calibration signal taken for each cylinder. This allows Coltraco’ range of liquid level indicators to detect the presence or absence of liquid behind the area of the container wall where the sensor is placed without disturbing the contents.  

Ultrasound interacts differently depending on the transducer and crystal. The diagram on the left (above) shows bulk waves in gas travelling radially inwards from the walls of a fire cylinder. Displacement is in the direction of propagation. The diagram on the right represents shear waves propagating radially over the surface of the cylinder from the point of the transducer contact. Displacement, in this case, is perpendicular to the direction of propagation. This information along with advanced signal analysis and calibration algorithms provide us with a clear picture of contents inside the cylinder and allows us to differentiate between the liquid and gas section.  

History of Ultrasonic Level Measurement 

Coltraco was founded in 1987 by father and son, Mr E C Hunter and Mr Carl Stephen Patrick Hunter OBE (current chairman). Mr E C Hunter served in the Royal Navy’s Submarine service for 27 years, as well as 5 years spent working for the Admiralty Research Laboratories, where he specialised in SONAR (SOund-Navigation And Ranging) technologies. His experiences allowed him to notice the need for a portable ultrasonic technology, which would enable the user to measure and monitor the contents of marine CO2 fire suppression systems. Technology at the time typically involved the weighing of gas cylinders or using radioactive sources, neither being convenient nor safe to use. In 1987 Mr E C Hunter was able to release the ‘world’s first dedicated marine portable liquid level indicator.’ It was then possible for users to find the liquid level within liquified gas bottles, without either disrupting the system or using cumbersome techniques. 

Throughout the years and decades, Coltraco Ultrasonics have continued to improve the Portalevel system, while expanding into the development of more products and systems; a large number of these use ultrasound to either test the integrity of a system or to measure the contents within. The Portalevel is used mainly in the Fire and Safety industry but is now used extensively in over 25 market sectors. The development of an ultrasonic liquid level indicator unit allowed for the replacement of old methods, since radioactive liquid level devices have become more and more expensive, and weighing heavy fire suppression cylinders requires a lot of time and is labour intensive.  

What does the Portalevel® marine range do?  

The Portalevel® marine range operates using the same principle as the Portalevel® fire cylinder range, however, is designed specifically with the marine sector in mind. Each unit is portable and comes with an extension rod used for inspecting cylinders in banked rows. Using this technology enables ship crew and marine operators to non-invasively locate the liquid level inside any single skinned cylinder welded or seamless marine fire suppression cylinder. Each Portalevel® unit is capable of detecting the presence of liquid externally; from water and liquid pressurised gases to clean agents and halons. The Portalevel® range can be used on an extensive variety of container types, composed of different materials, shapes and sizes, but are typically used on steel high-pressure compressed gas cylinders. 

Our technology is suitable for many applications, but it is most widely used as a replacement to both weighing fire suppression cylinders during installation and servicing, or replacement for the fitting of internal and invasive liquid level ‘float’ devices. Once the liquid level height inside a container has been located, the agent weight can be determined using the Portasteele® Calculator, which is designed to quickly convert liquid height to weight accounting for the cylinder size, agent type and temperature (see below).   

Inspections can take a little as 30 seconds for each bottle and displays easy to understand results indicating the presence of liquid or gas. This ultrasonic level sensing technology is suitable for other liquid level monitoring applications, including LPG gas level indication and in non-fire suppression containers such as water level measurements. Please, visit our case studies page or contact us to find out more.  

Converting Liquid Level to Weight 

Monitoring the liquid level in fire cylinders is a vital aspect of any fire suppression system maintenance schedule, however, understanding how the liquid level relates to the fill weight of the cylinder is equally important. Coltraco Ultrasonics offer, in conjunction with the Portalevel® range, the world’s first liquid level to agent mass calculator.  

The Portasteele® Calculator calculates the agent weight of a fire suppression cylinder. It does this by using the liquid level determined by our Portalevel® range or inversely by using the required fill level for a certain weight of suppression agent. The Portasteele® Calculator is sold as a stand-alone unit on a 7’’ hand-held tablet to be used in conjunction with our Portalevel® range. 

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British manufacturer of ultrasonic technologies, exporting to 120 countries and winners of The Queen’s Award 2019.

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