Hidden dangers
In high-hazard environments such as power generation and energy infrastructure facilities, fire and gas detection systems are designed to provide an early warning of potentially catastrophic events
Their effectiveness, however, depends not only on the sophistication of the technology deployed but also on the confidence that operators place in the alarms that are generated. When that confidence is eroded, often because of poor maintenance or system mismanagement, the consequences can be severe.
Repeated false alarms result in a loss of trust, creating a ‘cry wolf’ scenario in which genuine alerts risk being delayed, dismissed, or misinterpreted.
Causes of false alarms
False alarms with flame detection, sometimes brought about by reflected sunlight or flare reflection for example, are often caused by initial poor detector placement with the tilt angle not being ideal. Similarly, if gas detection sensors are hard to reach, they may fall out of the calibration owing to the extra effort required to reach them.
Both scenarios could be avoided by better initial system design and improved technology selection. Fire and gas mapping seeks to avoid false alarm triggers – a correct technology selection from the outset provides a robust foundation.
Engineered designs for specific scenarios
While engineered designs for specific scenarios might take more set up effort, they reap rewards when it comes to operational efficiency. A good example is enabling permanent remote calibration of gas detectors with the sensor mounted at height and the transmitter located lower down. The addition of calibration tubing installed between the two means calibration gas can be applied to the sensor without leaving the ground. This can be particularly relevant for hydrogen, which is the lightest gas, so sensors are often mounted at the highest points possible to detect re-accumulations of gas from leaks. False positives also cause disruptions to production uptime, and for green hydrogen systems, which use electrolysers, this can have bigger effects than just lost production.
Flame detection
Hydrogen’s more ‘exotic’ properties are well documented; the wide flammability range, extremely low ignition energy and the propensity to self-ignite, which is the reason why flame detection is so important when it comes to hydrogen safety.
Hydrogen jet fires are invisible to the human eye, have a high flame temperature and produce no carbon which creates that ‘smell of smoke’ that humans have evolved to associate with fire. All these characteristics can mean trust of your own senses may, initially, be in direct conflict with trust in the flame detection system. Radiation-based flame detection is the only option, and this can be Ultraviolet (UV)/Infrared (IR) or 3IR.
3IR compared with UV/IR
Of the two technologies, 3IR is more robust than UV/IR. While UV/IR relies on two different sensors, each contributing its own signal, 3IR uses three infrared sensors. As the name suggests, these three sensors work together with an intelligent algorithm that analyses the relationship between the three signals to determine whether they are characteristic of a fire. The algorithm is looking at radiation characteristics, in addition to random flicker pattern which can only be attributed to a flame, as opposed to two ‘on’ signals from two different sensors without the ability to analyse flame ‘flicker’ behaviour. This means the 3IR flame detector is less likely to be tricked by IR radiation sources which might meet wavelength parameters, but don’t behave like a fire, for example vibration hot pipework (black body radiation) or reflected sunlight.
Hydrogen’s burning velocity
Hydrogen’s laminar burning velocity is approximately seven times greater than methane, significantly increasing the potential size and pressure of an explosion, should an unburnt cloud of hydrogen gas reach explosive concentration. Consequently, using the correct method of leak detection is very important.
While using the right technology is crucial, human factors are also central to effective safety management. Even the most advanced detection systems rely on appropriate response from trained personnel. As a result, having clear procedures, regular training and safety drills are all essential to ensure that alarms are understood and acted upon correctly.
Added to this, a strong safety culture, where employees trust and engage with safety systems, is important. Reliability plays a role; when systems perform consistently and accurately, confidence increases, and personnel are more likely to respond appropriately.
For power engineers and operators, the message is clear: by selecting robust detection systems, prioritising maintenance, optimising system design, and ensuring that teams are fully trained and briefed, organisations can avoid the ‘cry wolf’ scenario and can ensure that when an alarm sounds, it is heard, trusted, and acted upon without hesitation.
Megan Hine is an experienced gas safety practitioner whose work in the safety sector spans over a decade. Her current role with Draeger Safety UK involves advising and supporting operators in gas safety monitoring and detection across a wide range of industry sectors, including pharmaceuticals, utilities, food and drink and manufacturing.
For more information visit: www.draeger.com/en_uk/Safety
Contributed by Megan Hine a gas safety expert from Draeger Safety UK
