The benefits and potential shortfalls of PPSs
William Makant of Plumis Automist discusses the benefits and potential application shortfalls of Personal Protection Fire Suppression Systems (PPSs) as a valuable new fire safety tool:
The LACoRS guide sets out guidelines to ensure ongoing safety in residential premises in England. The wording in this guide is quite telling in demonstrating how hard it is to ensure a safe escape route for occupants when it is an existing property, as opposed to a new one where a property can be designed to be safe. In existing buildings, one of the largest risk areas is inner rooms, from which escape can be severely impaired.
The term “reasonably practicable” in the guidance exposes the trade-off between practicality (and cost) and the need to allow for occupants to escape safely. It results in environment health officers having to make tough decisions on what is reasonably practicable without imposing excessive costs on housing providers. Personal Protection Fire Suppression Systems (PPSs), can be deployed much more easily and quickly than fixed systems, and can be provided as a temporary service, reducing the burden on budgets by imposing variable (and therefore flexible) operational expenses rather than a commitment to capital investment.
Yet, the major beneficiary of the existence of PPSs are not health & safety officers but the vulnerable, who represent a large fraction of fire victims in the UK and abroad. Most do not have the mobility to escape through the access rooms or protected escape routes described in the building regulations and the LACoRS guide. However rapidly a fire alarm alerts the occupants, it offers little benefit if residents cannot safely stay put. Furthermore, the source of the fire can be the immobile occupant him- or herself, making active fire suppression a critical piece of the puzzle in making fires tenable.
PPSs cannot be considered a panacea to fire safety, however. The main fragility of a PPS comes from its biggest strength: the ability to relocate it. In many cases, a PPS may be specified to target closely an immobile occupant who is at risk of being the ignition point of the fire (most likely a heavy smoker). In that case a PPS may act as a local fire extinguishing device rather than the more typical volume fire suppression offered by traditional sprinklers and watermist systems. Even though the wording might sound similar, the expected effectiveness of these two configurations are very different. One (the PPS) will be highly effective where it has been targeted, but ineffective outside that area; the other (sprinklers) will have a slower effect but over a much broader area of actuation. A PPS unit’s effectiveness as a local extinguishing device can be wiped out if moved to an unsuitable location, and even a PPS providing volume suppression will be ineffective if is removed for maintenance. The use of PPSs introduces a new need for the responsible person to be highly trained and aware of the principle of operation and limitations of the deployed system – their effectiveness is only as good as their user/specifier.
At least one PPS standard is currently in development, but care must be taken not to assume that a standard is a panacea for the specification of such systems. A standard should be flexible enough to allow for different configurations and to allow testing of the effectiveness of these different configurations; otherwise a standard will simply restrict what can be done without validating effectiveness. Standardisation is the enemy of customisation and fit for niche purposes.
If a standard is very prescriptive, it discourages the use of alternative means to reach the same objective (or even a more demanding objective) being sought by the responsible person. A standard is a good reference for verifying minimum performance levels but should not be used as the only specification or prescription – this is often seen in many industries, with arrival of a new standard accidentally eliminating all kinds of diversity, simply to reduce compatibility issues and transaction costs. The protection of human life from diverse fire risks should be guided but not constrained by the same benefits a PPS standard can bring.
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