Comment: Driving development in fire suppression
Protecting against fire risk plays a vital role in today's safety-first approach to operations, according to Tyco Fire Protection's Alan Elder.
The factors influencing the design, specification and use of fire suppression systems are changing. Typical considerations, such as the effectiveness of the system and agent, cost of ownership, and health and safety, remain key aspects of the selection process. Added to this is the impact of changes in environmental legislation and the greater effect these will have on the fire suppression industry, and subsequently the system choice available to fire safety engineers and system designers.
The impact of legislative change
Regulatory change translates into modifications, and sometimes transformations, of the solutions available to the market. In March 2014, the European Parliament supported a European Commission proposal to reduce the use of hydrofluorocarbons (HFCs) and greenhouse gases as part of the F-gas Regulation. This requirement to cut HFCs to 79% below average 2009-12 levels by 2030 was mandated effective from January 2015, with phase-down commencing from January 2016. Fire suppression systems are directly impacted by this regulation, as they have some of the highest global warming potential (GWP) in comparison to other sectors.
Given that some fire suppression systems have a service life of 20 years, it’s likely that older installations were designed with HFCs. Any HFC-based system already in-situ is also affected by the F-Gas regulation, including system recharging. As a result, fire suppression system owners not only face price increases as a resulted of limited HFC availability, but also must be aware of potential end-of-life and decommissioning costs for their existing systems when an alternative must be installed.
As the fire suppression market evolves and moves forward, there is a drive for innovation and technology development that supports viable alternatives to HFCs. The complexity of engineered fire suppression systems requires a reliable solution that is matched to the application risks and takes into account the specific considerations in relation to pipework design, venting and storage of the extinguishing agent containers.
Effective fire suppression
Even before the introduction of the F-gas Regulation, fire suppression solutions using inert gases have long provided an effective alternative to HFC-based and halon systems. These solutions combine three primary gases – nitrogen, argon and carbon dioxide – to deprive the fire of oxygen and eliminate the potential for combustion. Inert gases displace a significant amount of the atmosphere within the protected space in order to suppress a fire. For inert gases to successfully control a fire, the oxygen level must be lowered to 15% or less, requiring 35-50% of the atmospheric volume to be replaced within a discharge time of 60 or 120 seconds. This change to the atmospheric conditions in the space requires appropriate venting to exhaust ambient atmosphere and release the inert gas on suppression of the fire, and presents one of the most significant challenges to system designers when engineering a gaseous fire suppression system.
Conventional inert gas systems can cause potential over pressurisation, resulting in collapsed walls, blown-out doors and damage to a building’s structure, particularly in enclosed spaces such as data centres, electrical control rooms and laboratories. This is a result of the initial flow spike and peak pressure during initial discharge of the inert gas, and it is this pressure data that determines the specification of the system pipework and venting. To further reduce the risk of over pressurisation, larger size and high-pressure pipework based on hydraulic calculations defined by the system storage pressure is required, which can increase the complexity, cost and installation time of the fire suppression system.
To maximise the amount of inert gas within a specific system, the agent is stored in pressurised containers at up to 300 bar. This storage pressure differs across regional markets and is influenced by varying factors, with the typical storage pressure in Europe at 300 bar, 150-200 bar in the US, and 200 bar in the Middle East. In the US market in particular, storage pressures are lower than those in Europe due to the infrastructure that supports the refill of gas containers restricted to the 150-200 bar pressure range. The storage containers are the most expensive component in an inert gas fire suppression system, so designing a system at the highest storage pressure possible reduces the number of containers required to hold the inert gas. The current 300 bar inert gas fire suppression systems are maximising the capability of existing gas container design, and additional ancillary components such as orifice plates and manifolds are required in certain system designs.
Inert gas fire suppression
Overcoming the key design and engineering challenges of inert gas fire suppression systems is the stimulus for new, innovative technologies that can improve performance and reduce costs for system owners. To support this industry improvement, Tyco Fire Protection Products has developed its unique iFLOW delivery system for inert gas fire suppression systems.
The iFLOW system provides regulated discharge pressure to eliminate the potential for flow spikes and peak pressure. This controlled flow of the inert gas enables smaller diameter, lower pressure pipework and reduced pressure relief venting to help design engineers minimise complexity in their system, and therefore unnecessary pressure venting costs.
Time for a change
The shift in market dynamics within the fire suppression industry has increased the use of alternative systems to reduce the reliance on HFC and halon-based agents. Product development and innovation form a key part of this transition. It is experienced manufacturers, such as Tyco Fire Protection Products, working closely with industry associations and standards authorities, that are helping to drive the trend towards more effective, ‘greener’ fire suppression technology.