Gas mapping myths busted
In energy production facilities where hazardous materials and processes are present, fire and gas detection systems (FGDS) form a vital safeguard. They are essential for protecting personnel working in high-risk operational areas as well as for preserving critical plant assets
When installing these systems, scenario-based models are increasingly being used alongside traditional geographical gas mapping. But do they really guarantee lower investment costs? Incidents involving hazardous releases or flame formation usually result in production downtime and cost the operator a great deal of money. Consequently, flame and gas detection systems that are as effective as possible are of great interest to operators not only from a compliance but also from an economic perspective.
Gas mapping ensures that detection devices are positioned precisely and effectively to provide the best possible protection for all personnel, work processes, and the plant itself. There are essentially two approaches here: geographical and scenario-based mapping. But there are various myths still circulating around the best approach to use and why. In this article, Murray Farmer, Head of FGDS business development MENA at Dräger, dispels five of these myths.
Myth 1: CFD gives one correct answer
It does not. Computational Fluid Dynamics (CFD) is a method used in scenario mapping. It aims to predict the behaviour of certain substances on the basis of mathematical calculations.
To deliver appropriate results, the method always requires specific performance targets to be set. Parameters, such as the potential intensity of a fire or the extent of a gas cloud, and various environmental conditions must be defined. Based on that, scenario analysis is a valuable tool for determining the probability that a gas cloud could reach that extent.
In reality, however, the number of possible scenarios is usually vast. The mathematical calculation then becomes a purely probabilistic model, with outcomes heavily dependent on assumptions. This alone does not provide a basis for an effective safety design. Within a holistic approach, CFD should always be supplemented by other methods and executed by specialists.
Myth 2: Geographical mapping leads to more conservative designs than scenario mapping
Not in general. Classic geographical or volume-specific mapping analyses the individual characteristics of the industrial plant and its surroundings: the entire site is mapped to identify blind spots, for example, and thus determine the optimal number and distribution of sensors.
The risk of inefficient sensor placement arises if it is carried out too simplistically. A simple grid-based approach, for example, can easily lead to an unnecessary increase in the number of detectors. However, this is not the same as a professional, performance-based design with clear objectives. When executed professionally, geographical or volumetric mapping provides a consistent and transparent baseline leading to a more efficient and compliant design. They also benefit from reduced cabling and installation costs, installation complexity, which usually saves time, and less maintenance burden throughout the system’s entire lifecycle.
Myth 3: More detectors automatically mean increased safety
This is not the case. More detectors primarily mean higher costs – for procurement, installation, and maintenance. If complete coverage is achieved with a specific number of sensors, any additional devices are superfluous. Detection effectiveness is determined by how well the system meets the defined performance targets, not the number of devices installed.
Selecting the correct technology for the application and determining the optimal number and distribution of sensors requires a competent team of engineers with extensive experience. Their goal is always to achieve maximum safety at minimum cost to the customer: as many sensors as necessary, as few as possible.
Myth 4: Compliance means the design is good
No, this is not the case. Regulatory compliance is indeed the starting point; however, the real question is whether the design achieves the intended performance in practice.
Legislation generally prescribes safety measures, but it does not define how effective these must be. Some regions have highly developed regulations, whilst others are still in the development stage. Industry standards alongside health, safety, and environment (HSE) guidelines provide direction, but on their own do not offer sufficient detail to design a compliant system.
What is required is a thorough understanding of the underlying hazards and associated risks, possible escalation scenarios, combined with a deep understanding of the capabilities, strengths, limitations, and environmental sensitivities of the detectors, the triggers for false alarms, and their suitability for the specific application. This is what experienced partners and expert engineers bring to the table, leading to clear safety and performance targets.
Myth 5: Alarm-only detection provides the same value as a fully integrated protective function
Modern technology has its limits – yet in some areas it is faster, more efficient and more accurate than manual intervention. A simple alarm-only system that relies on an operator’s intervention cannot compete with a well-designed, integrated safety system.
Such systems do not completely replace the human factor but support it, creating a balanced interplay between individual decision-making ability and modern automated protection.
The crucial question when it comes to fire and gas mapping is therefore neither ‘geographical or scenario-based?’, but rather how effectively the engineering approach defines the risk and the required safety objectives. What is crucial is to understand the existing infrastructure and its specific challenges before the modelling begins.
Based on this understanding, appropriate performance targets can be defined and the most suitable mapping approach selected. If companies follow this principle and the five myths presented here, they will design their fire and gas detection systems to deliver both maximum safety and optimal cost efficiency.
For more information visit: www.draeger.com
Contributed by Murray Farmer, head of FGDS business development MENA at Dräger
