Following on from the correct application of fire detection in industrial applications in the June issue, we now look at selecting the appropriate fire detection.
Although regulatory requirements typically stipulate where and when fire detection should be installed, ultimately the choice of detection equipment is left to those who quote and are involved in the installation process. The question is “what is the criteria for selection?”
An approach, taking into consideration the many variables in industrial applications should be considered. Figure 1 outlines some of the key points to consider in order to determine system suitability and the appropriate fire detection product for the job.
In relation to individual product choice many manufacturers claim their equipment is up to the task, so how then do we prioritise our choice? Perhaps the first step is to conduct a simple evaluation.
The two key points that shouldn’t be overlooked and essentially form the basis for the selection of the right equipment are ‘consequence of loss to fire’ and ‘cleanliness of the environment’ in which the detection equipment must operate.
Consequence of loss to fire can equate to how well the detection system can detect a fire, i.e. if the sensitivity is poor, the risk and loss will increase.
Cleanliness of the environment to be protected: If the equipment chosen is unable to cope with the conditions (environment cleanliness) and operate with minimal service and maintenance it can be deemed inappropriate for the risk.
In addition, there is the aspect of longevity: what is the likely life cycle of the product? The more difficult the environment, the more robust the equipment must be. Also, the harsher the environment, the more intelligent the fire detection system must be... and let’s not overlook the ability to maintain the system in terms of access and cost.
To best illustrate this look at a simple selection matrix that has been developed and can help in the evaluation. The chart (Figure 2) has been termed the 2 x 2 Fire Detection Selection Matrix. It provides a basic concept in which to view the selection of fire detection equipment for a number of market sectors and environments.
The X axis considers the environment, clean to dirty; the Y axis depicts the fire risk from low to high with consideration to detector sensitivity. There are four quadrants that represent the main fire market sectors. Here is a brief explanation.
The generic solution
The generic solution or quadrant 1 can be defined as the sector where the fire industry conducts the bulk of business, i.e. the cleaner environments which are considered low risk.
Typical applications include residential and commercial environments, office blocks, health care facilities, shopping centres and the like. The fire industry in general services this sector well. Structures and applications are assessed and detection systems installed in line with codes and standards.
A variety of products is available to service this sector, e.g. point, thermal and beam detectors. Aspirating smoke detection (ASD) systems are very capable of addressing this segment and have indeed been used, although point detectors are the most popular choice. Cost is certainly a significant factor here since compliance to minimum codes and standards is all that is required for the client. Fire contractors make their bread and butter from this sector which is very competitive.
The high risk
The second quadrant, the high risk, represents clean environments, but with high risk. Failure to respond at the early stages of a fire in these risks threatens business continuity and/or lives. These high risk applications require suitable high capability detection with sound performance where any fire incident could incur huge losses.
Depending upon the application, specialist fire consultants and contractors – and in some cases insurance – will assess the risk and determine how the application is to be protected. Minimum requirements here are often above those suggested by codes and standards and performance-based solutions are often considered in larger facilities. Applications comprise mainly of telecommunications, computer and data centres, semiconductor and clean rooms, etc. Many electrical switch/substations and control rooms also fit in this category. It is also not uncommon for large open spaces and warehouses where critical equipment or goods are stored to be considered in this quadrant.
While point detection is certainly installed in these facilities, ASD is still the chosen solution used in these high-risk areas where early warning detection is paramount.
Set and forget
The term ‘set and forget’ is used here since equipment often deemed appropriate for the application by manufacturers, is installed with the confidence that it will perform with minimal issues and maintenance . . . in essence, install it and forget it.
This solution falls in the low risk/dirty quadrant, typically the industrial sector where the challenge is to select a product that will provide a level of fire detection without false alarm activity. The effort put in at the concept and design stage ensures the effectiveness of the detection system.
Unfortunately the fire industry often places too much reliance on the products used in sector 3 without understanding the environmental challenges. Owners and developers may even take a ‘let it burn’ approach to these sites. They just want to get everybody out and pass the responsibility to the fire services and their insurers.
A diverse range of industrial environments fit in this sector and this tends to be where many of the issues occur. Products considered for this sector include thermal detection, CO, beams, linear heat cable, ASD, etc. – even specially designed detectors such as multi-criteria or multi-sensors have been developed to specifically try to minimise nuisance alarms. However, since industrial working environments can be hostile, the conditions can render many of these forms of detection ineffective.
On the other hand – and contrary to the belief of many in the industry, a realistic and viable option for smoke detection in hostile environments is ASD. A system can be specifically engineered and designed for the environment with an appropriate ongoing maintenance plan that can perform as intended.
Difficult and special
Perhaps the most involved sector of all in this matrix is the ‘difficult and special’. The solutions in this sector are purely industrial and must be considered in line with the risk present and the environment to be protected. Any high value processes/assets contained within these industries require special attention. Examples can include:
* Dusty/dirty – flour mills, grain silos, fertiliser plants, mining, potentially explosive environments.
* Freezer/cold rooms – damp areas, food processing.
* Corrosive – processing wash-down, battery manufacturing, chemical storage and processing.
The solution in most situations is not cheap, will likely require some system engineering and will come with a maintenance requirement needed to ensure continued operation. Specifiers and end users in this segment usually educate themselves well with regard to the options available before making a decision. Once again ASD has been used successfully in this sector.
All too frequently detection equipment suitable for the ‘generic solution’ is misapplied and used in the other quadrants. The equipment selected is installed without due thought to the application or environment or the costs associated with maintenance.
Nevertheless, regardless of the type of detection chosen, the two key factors that should not be ignored i.e. the consequences of loss to fire, and the cleanliness of the environment to be protected.
If these two factors are not considered then:
* A ‘generic solution’ into ‘set and forget’ results in poor detection, continued nuisance alarms and increased cost of ownership.
* A ‘generic solution’ into ‘high sensitivity’ exposes the client to increased loss through delayed detection.
* A ‘set and forget’ into ‘high sensitivity’ results in high exposure to loss.
The ‘difficult and special’ usually doesn’t go wrong as the client, engineer or plant manager has a high level of involvement in the solution.
The matrix provides some food for thought in terms of the selection of detection equipment and is by no means an answer to evaluate all applications. Aspirating smoke detection is a real option and a well-designed and engineered system using purpose-built equipment.
The next step would be to become familiar with the site, risk application and environment with the view to installing an ASD system.
For more information, contact Derek Waddell, regional sales manager, Xtralis, +27 (0)82 316 2601, dwaddell@Xtralis.com
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