Transitioning to Environmentally Responsible Firefighting Foams at Airports in the MENA Region (Part 2) – Fixed Systems Protecting Hangars
Since writing Part 1 – which focussed on the Fire & Rescue Services (ARFF) – we have seen new EU legislation come into force in September this year restricting PFHxA. EU 2024/2462. In Annex XVII to Regulation (EC) No. 1907/2006, entries were added in relation to Civil Aviation as follows:
Shall not from 10 October 2029 be placed on the market, or used, in firefighting foams and foam concentrates for civil aviation (including in civilian airports) in a concentration equal to or greater than 25 ppb for the sum of PFHxA and its salts, or 1,000 ppb for the sum of PFHxA-related substances.
Clarification on the above point through Germany, Sweden and the UK has indicated that the above covers NOT only the Fire & Rescue Services (ARFF) but also Hangars and Fuel Storage if these sit within the airport boundaries. Whilst the transition deadline was expected for the ARFF mission, for the fixed systems in the hangars and fuel storage, this has come earlier than expected as it was thought that these applications would only be covered as part of the pending “PFAS in firefighting foam legislation”!
HANGARS:
For hangars, the most common foam agent deployed is AFFF, either in foam deluge plus underwing, or to provide coverage of the floor area when a high-level water (sprinkler) system is deployed. High Expansion foam concentrates typically are not manufactured with fluorochemicals that can degrade to PFHxA, but potential exists for contamination if the original foam concentrate was blended by the manufacturer in the same tanks as were used for foam concentrates containing the FTS 6:2 fluorotelomer.
Whether a new build or transitioning to fluorine-free foam concentrate, effective fire protection should be ensured by selecting appropriate design standards. Factory Mutual (FM) occupancy data sheet 93-7 or UFC 4-211 for US Military Hangars outline minimum requirements for system design. The most common design standard of hangars is NFPA 409. The latest 2022 edition of NFPA 409, however, does not yet include SFFF as a permitted foam type! There are several foam concentrates, including the Enviro USP from Fomtec, available on the market that meet many of the same standards as the fluorinated foams.
PROVING ENVIRO USP AS A SUITABLE AFFF ALTERNATIVE (REPLACEMENT) IN HANGAR PROTECTION:
As stated above, whilst we are waiting for the 2026 edition of NFPA 409 where we expect the use of SFFF to be addressed, Fomtec, in cooperation with Messrs. Viking, have progressed the testing and approvals for Enviro USP with foam/water sprinklers, monitors and grate nozzles to cover the requirements for foam systems in hangars. UL Listings and FM approvals are in place that allow deployment of Enviro USP under NFPA 11 – 1.2.2:
1.2.2 Nothing in this standard is intended to restrict new technologies or alternative arrangements, provided the level of safety prescribed by the standard is not lowered.
High-Level Foam Water Deluge / Closed Head Foam Water Systems
As per NFPA 409, Foam Water Deluge is a suitable primary protection and is commonly used in Group I and Group II Hangars. Minimum application rates of 0.16 gpm/ft² (6.5 lpm/m²) are allowed with AFFF and non-aspirated sprinklers, and 0.20 gpm/ft² (8.2 lpm/m²) when using aspirating sprinklers. Proving the suitability of Enviro USP required testing and listing/approving the foam concentrate foam water sprinklers from Viking according to UL 162 and FM 5130 test protocols.
Testing to FM 5130 test protocols allows testing and approving on heptane or other hydrocarbons at a minimum test density of 0.20 gpm/ft², which was carried out successfully initially on heptane with the K5.6 (K80) heads with the approved details as below. As Jet A1 has a vapour pressure greater than heptane, to get an FM approval on Jet A1, further testing with this fuel is required, and testing with K5.6 (K80) pendant sprinklers was also successfully carried out, again as indicated in the table below:
FM APPROVALS: JET A1 & HEPTANE
Low-Level Secondary Foam System for Use as Underwing Coverage or Full Floor Area Coverage
Here we have the options of:
- Oscillating Monitors
- Grate (in trench) Nozzles
- High Expansion Foam System
i. Oscillating Monitors: As per NFPA 11, although the hazard in a hangar would be regarded as a SPILL fire, the minimum application density for a type III application with SFFF is 0.16 gpm/ft² (6.5 lpm/m²). This represents a 60% increase over the application density of 0.10 gpm/ft² (4.1 lpm/m²) allowed with film-forming foams. Enviro USP has been tested and listed to UL 162 with the 2.5” monitors from KCA/Viking with their KNN nozzles at 100 psi (7 bar inlet) to give flows of 250 gpm (approx. 950 lpm), 350 gpm (approx. 1,325 lpm) or 500 gpm (approx. 1,895 lpm).
ii. Grate (Trench Nozzles): Grate or Trench nozzles provide discreet foam application and are typically installed inside drainage trenches. Viking has tested and approved the grate nozzles with USP so that systems deploying this system can do so based on the same minimum application density as AFFF.
iii. High Expansion Foam Systems: High expansion foam systems should be largely unaffected by PFAS legislation. Fomtec’s LSxMax is UL 139 listed with the Viking High Expansion generators.
Supplementary Foam Hose Reels
NFPA 409 requires a minimum of two hose lines flowing 60 gpm (227 lpm) for 20 minutes. Enviro USP has been internally tested with both aspirating foam branches and non-aspirating nozzles on fuel in-depth fires, ensuring compliance.
Foam Storage and Proportioning
This article has focussed on the discharge devices and the design standards for deploying SFFF (specifically Enviro USP). Proper proportioning is critical to performance, and we recommend that equipment tested and approved with Enviro USP be used.
Final Remarks:
Transitioning the foam system in an aircraft hangar is not just about “swapping out” the foam concentrate, and Enviro USP is not a “drop-in” replacement. However, for most design options under NFPA 409, Enviro USP can be deployed at the same application densities as existing AFFF. This statement is supported by extensive testing, UL listings, and FM approvals gained with Viking hardware.
Please visit www.fomtec.com for more information.
© Viking S.A, main image published with thanks from Viking S.A.
