There is a clear trend toward including fire suppression in newer units, but with systems, comes the requirement of maintenance. The assumptions in the installation, commissioning and maintenance of gaseous extinguishing systems are that they are highly pressurized and thus risk leaking and discharging, hence why annual inspections are required.
Large wind companies, such as E.ON, have now begun investing in both in-house and third party operations and maintenance, driven by safety and quality concerns. Inspection should include an evaluation that the extinguishing system continues to provide adequate protection for the risk. This is essential under ISO 14520 where gaseous extinguishing systems have to be designed in relation to the discharging agent hold-time (if the room cannot hold the agent because of leaks the agent will disperse and not extinguish the fire) and discharging agent peak pressure (if the pressure is too high for partition walls or suspended ceilings they will be blown apart or damaged and possibly destroying the room integrity). However, routine maintenance is liable to be overlooked or given insufficient attention by the owner of the system.
ARE ANNUAL CHECKS SUFFICIENT IN RISKY ENVIRONMENTS?
Given that offshore wind parks require huge investments and are difficult to reach in the event of a fire, an emergency automatic fire extinguishing systems is a must for insurance cover. But what if the suppression systems that are installed in the turbines to protect life and infrastructure do not release on actuation? Gaseous extinguishing/suppression systems are installed to protect against special hazards in critical infrastructure as their key objective. They deliver the infrastructural resilience that wind turbines require. If it is a known fact that there is a long response time to wind turbine fires, then it is unacceptable that the dynamic suppression systems are left unattended 364 days a year.
A CALL FOR CONSTANT MONITORING OF WIND TURBINES
There is a call for remote fire alarms in the turbines due to the lack of easy fire servicing stations, so why not also for the gaseous systems? Why have an alarm system to alert fire services of the fire if the protection system cannot secure the nacelle? A dynamic system needs monitoring. The reality is that gaseous systems are checked for contents annually because they are pressurized and anything that is dynamic offers risk of loss of contents, but this fails to deal with the probability of discharge or leakage for the 364 days per annum in the interim between certification checks.
Gaseous extinguishing/suppression systems are installed to protect special hazards in critical infrastructure as their key objective. If the hazard is special and the infrastructure critical then this is the case for the constant monitoring of the suppression systems that aim to deliver the protection of them.
Coupled to this is a complete lack ultrasonic room integrity testing after the gaseous system has been installed. As buildings age or their internal use is changed leak sites develop. If the gas cannot be “held” in the room on discharge during a fire event the probability of its suppression diminishes in direct proportion to the size of the leak sites. Room integrity tests are imperative for the determination of both the Hold-Time and the Peak Pressure needed for successful fire suppression.
The level of leakage is carefully monitored in order to ensure the correct agent concentration is achieved; room integrity must be ‘tight’ enough to ensure sufficient retention time according to NFPA Standards or ISO 14520, yet remain ‘loose’ enough to prevent enclosure damage at discharge. The presence of undesired and unregulated leak sites reduces room integrity and will hence dramatically impact the Hold Time and Peak Pressure, placing room contents and potentially wall structures at risk. It is accepted that in wind turbines vibration can loosen connections while dirt, dust, and temperature extremes are known to cause unwarranted discharge. Additionally, openings in the turbine housing significantly inhibit achieving the designated agent concentration. Devising a solution to overcome these challenges can add significantly to the weight in the turbine.