Fire Friday #6: Harsh Environments

Why is AP Sensing’s Fiber Optic LHD system suitable for harsh environmental conditions?

AP Sensing's fiber optic heat detector combines many advantages that are particularly useful in applications characterized by harsh environmental conditions. This is especially true for traffic, industry and production facilities. In such applications, conditions prevail that are characterized by high dirt and dust loads, corrosive gases, strong electromagnetic fields and large temperature differences. Examples of these include traffic tunnels, petrochemical plants, mining operations and the steel industry.

Harsh environments present a challenge for providing early, reliable fire detection that is also adapted to the requirements of the specific application. At the same time, a detection system should not only be reliable but also economically justifiable in the long term. Considering the technology and properties of a fiber optic solution, two elements have a decisive advantage over other fire detection solutions. One of these is the intelligent and flexible evaluation of the data, and the other element results from the use of a passive sensor.


Smart Alarming

The evaluation - and thus the detection or alarming of a fire - is based on the analysis of a thermal profile of the monitored object, measured in real time. Our evaluation criteria are flexible and therefore programmable and adaptable to the application at any point along the sensor. Any number of different evaluation criteria can be used to ensure an optimal balance between fast, reliable detection and high false alarm resilience. If needed, hundreds of different zones can be set up, representing different alarm criteria.  AP Sensing's fiber optic heat detector works with up to seven different evaluation criteria per zone. If there is a need to optimize the detection behavior, these criteria can be changed centrally at any time, or remotely if necessary.

The Sensor

The sensor element itself is a simple fiber optic cable, containing standard optical fibers. AP Sensing, however, uses an optimized cable design with improved robustness, thermal behavior and durability. The sensor cable is passive, meaning that it does not contain any active mechanical or electronic components. Therefore, the cable is resistant against dust, dirt and corrosive gases, as well as maintenance-free  – if necessary due to regulation, mandatory system maintenance is conducted via the evaluation unit and can also be conducted using remote access if necessary. Thanks to the pure optical measuring principle, distances to objects emitting electromagnetic radiation do not have to be considered; the sensor cable is immune to any kind of EMI and RFI. 


Intrinsically Safe Laser Product

However, when installing the cable in hazardous areas, it should be noted that not every optical solution is intrinsically safe. After all, the fiber carries an intense light that is generated by a powerful laser. If the cable is installed in a hazardous area, laser light can escape at a fiber break point which occurs via mechanical damage. If this laser light is focused on a surface, it may become a source of ignition due to heating.
Thanks to our patented "Code Correlation" principle, AP Sensing's linear heat detectors operate with average laser powers of well below 20 mW and are thus below a laser power of 35 mW, which is considered as the critical threshold for potential ignition. As a result, all of AP Sensing fire products are rated intrinsically safe, certified by ATEX and IECEx, and can be safely used in the most challenging and hazardous environments.

Response time, spatial resolution, and alarm zone configuration: what is important when selecting a Linear Heat Detection system? Find out more in our weekly series.

AP Sensing Fire Friday