Fibre-Optic Distributed Temperature Sensing

Range of fibre-optic monitoring systems designed specifically to enhance the fire safety of critical infrastructure and personnel.


Fibre-Optic Distributed Temperature Sensing

Patol’s range of fibre-optic monitoring systems are designed specifically to enhance the fire safety of critical infrastructure and personnel. We provide solutions for fire detection utilising linear heat detection technology, monitoring environments over a long range distance (linear assets), typically in special hazard environments.

LHD systems can detect a fire anywhere along the length of the linear heat sensing cable, over a distance of several kilometres. Patol utilises fibreoptic distributed temperature sensing, one of the key technologies available within this field. Combined with our smart software and services, this solution provides operators with the right information at the right time.

Whether the asset is in a remote location or a busy inner city, Patol’s solutions enable swift decision making to minimise damage, avoid catastrophic failure, and reduce financial, environmental and reputational risk.

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More about Fibre-Optic Distributed Temperature Sensing

Highly accurate, real-time temperature data over long distances.

Patol fire detection systems provide reliable and intelligent fire detection and asset monitoring on projects throughout the world.

Our fibre-optic systems have been delivering added value through highly reliable fire detection and lead the way in monitoring temperature and detecting incipient fires within a range of multidiscipline environments with over 1000 devices installed and over one million days of operation.

The fibre-optic technology utilised within Patol Fibresense Distributed Temperature Sensing (DTS) systems combines the benefits of detection speed, reliability and versatility in one proven solution. The unique feature of fibre-optic DTS technology is that it can accurately locate hot spots to within a distance of 1m with a temperature accuracy of within ±1°C. It therefore combines the benefits of analogue LHD rate of temperature rise with digital LHD location accuracy.

The Fibresense DTS Control Unit connects to Fibresense DTS Cable and determines temperature and distance data at thousands of points along the cable which can be up to 10km in length – another benefit of Fibresense DTS. In addition, the system is able to monitor the movement of the hot spot, or multiple hot spots, in terms of position and temperature in real-time.


The ultimate linear heat detection solution.

Conventional linear heat detection systems typically use digital cable, analogue cable, pressurised tube and multipoint detection. However, there are significant advantages of utilising fibre-optic sensors over conventional technologies, including:

  • Early Detection. Earlier identification of the rate of rise and so can detect earlier than other technologies which rely on discrete trigger points at a higher temperature.
  • Truly distributed. Due to the distributed continuous nature of the fibre there is complete coverage of the asset with no gaps.
  • Versatile. Fibre-optic sensing technology resistant to electromagnetic interference and is intrinsically safe, enabling it to be used in a wide variety of installations.
  • Low maintenance. Completely passive, corrosion free, no apertures, joints or moving parts, ensuring a very low maintenance option.

Unique Features

The unique feature of Fibresense DTS is that it provides a continuous temperature profile along the length of the sensing cable and not at discrete sensing points, which must be pre-determined. As a result, Fibresense DTS is able to determine not only the current position, but also the progression of a fire, by measuring the temperature along the sensor cable in real time.

System designers do not therefore have to take into account the precise location of each sensing point, which allows time- and cost-efficient installation compared to traditional sensors. Fibresense DTS provides very early temperature rise detection and monitoring, distributed along a length of fibre-optic sensor cable, configurable into multiple detection zones to suit the particular installation.

Optical fibre offers several important advantages as a sensing medium. Signals are immune to electromagnetic interference thereby ensuring integrity of electrically noisy areas, for example around power and transformers. As no electric current is used in the sensing fibre and the fibre is a relatively inert and dielectric (non conducting) medium, it is safe technology to use in hazardous environments.

Control Units & Cables

Fibresense DTS is supremely networkable. Embedded software enables the control units to operate independently of an external controller via TCP/IP or RS232 serial connector, eg PC. Adjustable alarm levels may be set for each zone, providing a programmable platform to suit many fire detection applications and installations. Alarm decisions are communicated directly to the main Fire Alarm Control Panel (FACP) by relay contacts. Alarm, real-time temperature and distance data may be sent via a Modbus communications path to a thirdparty system, such as SCADA (Supervisory Control and Data Acquisition), for controlling ventilation or extinguishant systems.

Control Units

  • Control unit technology
    The Fibresense DTS control unit contains a pulsed laser which sends in an approximately 1m pulse (equivalent to a 10ns time) into the fibre-optic. As the pulse travels along the length of the fibre-optic, it interacts with the glass. Due to small imperfections in the glass, a tiny amount of the original laser pulse is reflected back to towards the control unit. By analysing the reflected light, the unit is able to calculate the temperature of the event (by analysing the power of the reflected light) and also the location of the event (by measuring the time it takes the backscattered light to return) to typically within a metre.
  • Control unit sensing circuits
    Typically DTS technology uses a standard telecoms fibre-optic cable and specialised cables or sensing points are only required if measurements are required at temperatures greater than 100°C. The sensing fibre is typically based on multimode fibres for shorter ranges (up to 40km) and single mode fibre for long ranges (40- 100km). When configured in a loop, in the event of a break in the sensor fibre, or significant increase in optical loss, the Fibresense DTS control unit indicates an alarm. The system measures from both ends of the fibre, ensuring continued fire protection over the entire fibre length.


Fibresense DTS cable is Flame-Retardant Non-Corrosive (FRNC) and Low Smoke Zero Halogen (LSOH), with a Kevlar strength layer protecting a central structure comprising a gel-filled thermoplastic loose tube.

The cable is available in two versions:

  • Fibresense Armoured Tube (AT) Cable.
    Armoured Tube cable is widely used in a variety of linear heat applications and is optimised to work with Patol’s range of DTS systems.
  • Fibresense Thermoplastic Tube (TT) Cable.
    Thermoplastic Tube cable is typically deployed in applications requiring a non-metal cable, for example where there is a high level of electro-magnetic (EMC) activity.


Cable Trays & Racks

Fibresense DTS is ideally suited to this type of application as it can be installed very close to the point of risk giving the earliest possible detection of an overheat condition.


Fibresense DTS is particularly suitable as it can be installed where high levels of dirt, dust, wind and moisture exist and still be effective.

Car Parks

Detection systems in car parks are often subject to the elements and vandalism. Fibresense DTS is ideal for this type of application where wind, dust and moisture are present which can often lead to false alarms with other systems.


Fibresense DTS will protect these facilities without affecting production status. Refineries utilise numerous processes involving flammable liquids and toxic chemicals. Every aspect of these processes can be monitored by Fibresense DTS.


With Fibresense DTS, the warehouse and racking can be split in to zones to reduce the search area and to activate the relevant sprinkler/suppression system to restrict the spread of fire.

Escalators & Travelators

The public nature of this application means that it is crucial to have the earliest possible detection system to initiate emergency procedures.


Fibresense DTS detection zones are calculated according to the length of tunnel, and can be linked to water, gas or foam suppression systems for localised fire fighting or activation of extraction systems.

Power Generation

Fibresense DTS answers these problems with a cable-based system that can be fitted in restricted spaces and additionally is immune to the vagaries of dirt, dust and moisture which can upset other detection technologies.

Project Support Services

Fibresense DTS equipment is designed for installation by certified fire engineering companies. Patol adds value to its Fibresense DTS fibre-optic temperature sensing solutions through the provision of comprehensive support, drawing on skills and experience right across the Patol organisation.

By operating an end-to-end solution, from survey and design development to training and customer support, Patol provides critical asset monitoring to meet the individual needs of its clients. As necessary, experienced teams are able to adjust and meet changing application needs throughout a project’s life span. As a result, Patol solutions are manageable, achievable and pleasurable, leading to successful commercial results.

Our project support services include:

  • Feasibility studies
  • Budget analysis
  • Surveys
  • Installation support
  • Operator training
  • Customer support

Feasibility studies provide an analysis of all of a project’s relevant factors, including economic, technical and scheduling considerations, to ascertain overall project viability. The purpose of the budget analysis is to assess whether the allocated funds meet the project’s goals.

Installation surveys are a means of providing a detailed evaluation of an infrastructure’s condition and involve an extensive inspection. Our specialised team will talk through your project at length, covering all the details and possibilities with you. Only then will they provide an indepth recommendation.

Ultimately, our customers do not buy systems – they buy system productivity. This is why Patol offers operator training for more productive and profitable system ownership, and our customer support covers a range of services to assist clients in making cost effective and correct use of our systems.

Overall, Patol is here to guarantee the success of your project from start to finish.