Deck Integrated Fire Fighting System for Helipads (DIFFS)
- Main fire fighting systems
- Complementary media
- Rescue equipment
The best way to meet all fire safety requirements and to afford the maximum fire protection for helicopter crew, passengers, building occupants and third parties adjacent to the building is to install a DIFFS unit to the helipad.
DIFFS is an acronym for “Deck Integrated Fire Fighting System”. A DIFFS unit consists of a skid which processes firewater inflow to output foam or water. It is then piped to multiple nozzles which are distributed evenly across and installed flush with the helipad surface. In case of fire, these nozzles automatically telescope and spray water or foam evenly onto the deck.
Unperforated steel, concrete and aluminium helipads require the use of AFF foam as the fire-fighting agent but for the Enhanced Safety™ helipad which contains a built-in, automatic fire suppression system, a water-only DIFFS is allowed by UKCAA CAP and ICAO standards.
We have pioneered and developed a next generation, automatically operated DIFFS unit. This system differs from existing ones in that it is sensor activated for automatic operation, is fully fire tested in accordance with 2008/2009 standards and latest civil aviation codes.
Standard Aluminium Helipad
Passive Fire Retarding Aluminium Helipad
Ring main foam system (currently available for helipads up to 16m)
Advantages of DIFFS
- Safer: rescue crew can work concurrently with spray activation instead of being stuck behind monitors. This frees up rescue and firefighting crew to help with helicopter evacuation
- Automatic: less chance of human error in traumatic situations
- Nozzles spray uniformly: fire out in < 15 seconds in the worst case
- Firefighting platforms can be eliminated or made smaller
- More efficient fire suppression and not affected by wind
- Multiple nozzles less affected by blockages caused by debris
The system overview here relates to a foam DIFFS unit; a water DIFFS unit is essentially similar but somewhat simpler in configuration/hardware.
DIFFS system overview
The foam DIFFS system consists of an electric operated deluge valve, embedded spray nozzles, remote manual stations, UV/IR flame detectors, deluge valve release panel, foam storage tank containing foam concentrate 1% or 3% AFFF and a turbine foam proportioner.
The corrosion resistant spray nozzles are spaced evenly across the helipad and sit flush with its surface to provide an optimal and even coverage of the helipad surface. The nozzles do not present any trip hazard as they protrude only a few mm above deck.
The unit is capable of being activated either manually (by way of the remote manual stations) or automatically (by way of UV/IR or visual flame detectors). All units have multiple activation methods with the most common being automatic activation with remote, manual override buttons.
Upon detection of a fire via the detectors, or on manual activation, a foam-water mixture will be released through the deluge valve-foam inductor unit, through the firewater piping network and to the spray nozzles. The foam is inducted through a turbine foam proportioner which eliminates the need for a separate foam pump and also gives a much more stable and correctly proportioned foam supply throughout the discharge period. 3% AFFF is usual but 1% solution can also be used.
The entire system has been tested and approved in accordance with UKCAA CAP437. Live fire tests were also carried out in accordance with CAA standards and witnessed by Class and the system is fully approved for us on any helipads following UKCAA or ICAO standards.
Aluminium Offshore and its leading role in the acceptance and development of DIFFS in CAP1264 and CAP437
In November 2008, senior representatives from international organizations including the UK CAA and members of the ICAO Heliport Design Working Group attended live fire tests on the XE Enhanced Safety™ helipad with a DIFFS capability. The tests were organized by Aluminium Offshore and the overwhelming response from all representatives in attendance was support for the passive helipad with DIFFS option as a world best practice for helipad fire control.
The UK CAP437 guidance material was revised in December 2008 following the demonstration of XE Enhanced Safety™ Deck with water based DIFFS capability.
In 2016, the first edition of CAP1264, Standards for helicopter landing at hospitals, draws a similar reference to CAP437 regarding the use of water as firefighting medium for DIFFS on a passive fire retarding helipad.
ICAO revision to the Heliport Manual moving forward from March 2020 includes reference to the benefits of helipads with a passive fire suppression capability.