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  • Writer's pictureChas Murrell

OneQ50 - Continuous Foam Operations at Major Fire Incidents

It’s strange how an incident in a far off land can trigger a response in you. However, such an incident for me was the overrun of Air France Flight 358 at Toronto in Canada on the 2nd of August 2005. The very next morning found myself and fellow Senior Fire Commander Dean Hawkins standing in the mangroves at the southern end of an international airport runway doing the “what ifs” of a nasty aircraft overrun and testing our consciences’ with the benefit of theoretical hindsight.

It seems then, as it does now, that an incident in areas such as these is going to be a toughie; given inaccessibility, lack of immediate reticulated water supply, difficult terrain and other elements that could be learned from incidents such as Flight 358.

The raw news footage of ARFF vehicles operating and then apparently withdrawing to replenish is typical of accepted doctrine and let’s face it, if there’s nothing else in place, it’s the only way we can really do it under the circumstances. ARFF operations on the Flight 358 fireground were reminiscent – to me at least - of the huge Coode Island Chemical Fire in Melbourne, at which ARFF vehicles were forced to use the same tactic of withdrawal / replenishment / re-attack and then try to regain what progress had been lost during the withdrawal / replenishment / re-attack process. That’s BEFORE you can make any further process. Is there not at least one other (better) way, that also reduces time on the fireground?

That (better) way would allow us to use at least one ARFF Tender in static mode in continuous foaming operations and remove the need to withdraw / replenish / re-attack. Ah, life is sweet in a utopian world….. Having now set the scene, allow me to digress.

The Rosenbauer Panther is an excellent machine especially in the hands of dedicated, competent and keen crews. The Panther monitor can discharge at 80 L/sec (100%) or 40 L/sec (50%) at the flick of a switch on the monitor “joystick” – this feature will become important later….

Over run area pre-planning had already revealed that monitor throw was sufficient to reach the opposite bank of the tidal creek, but how long could monitor discharge (“Q”) be sustained if only one vehicle was within or could get within, monitor range? With these prospective operational issues firmly identified it was time for the pragmatic neurons to start communicating – we knew what the problem was, how could we solve or mitigate it?

It was discovered earlier in 2005 soon after we took local delivery of the first Panther that we could induct directly into the pump proportioner from an external foam source, and trials were conducted to gain enough information for practical use. Our previous vehicles did not have this capability - nor do we use compound gauges.

This was exciting news it meant that if we could keep the water supply up, we could run the monitor at 100% Q for extended periods; no longer needing to stop discharge & withdraw to top up foam & also eliminated the time taken to fill the foam tank. It provides the ability to use different foams without contaminating ARFF foam already stored in the vehicle tank. The benefits are truly very operationally significant.

Without a little lateral thinking though, the fill rate of the Panther - using both its BIC (British Instantaneous Coupling) male couplings - would remain at approx. 40 L/Sec. Not enough for continuous monitor operations. Was there a way of increasing the fill rate? A single BIC coupling is rated upto 40L/sec throughput. We were just over half that, so the good news was there was plenty of room to improve!!.

Given the potential throughput of the BIC filler coupling, what if we could get some sort of collector head into which could be connected 2 x 64mm hoses. What then? Many services use / used “collector heads” or “dividing breaches” to manage water flows, ARFF in our case doesn’t. So I phoned one of the many professionals at the local brigade who loaned me an old dividing breach to try – alas there was only a very marginal improvement in flow.

We thought, “maybe the design is not optimal, perhaps if we increase the angle to a sharp “Y”, increased the diameter of the collector to match that of the internal piping within the Panther and welded the couplings such as there was no restriction to flow?” Thus our “Y” was born and provided a fill rate under optimal conditions of 35 L/sec. With a “Y” in both fillers we could achieve a fill rate of 70 L/sec – it wasn’t going to get much better than that. Welcome to the “Y” generation!

And thereby… OneQ50 was able to develop. We could apply One hundred percent monitor discharge (“Q”) until the water supply fell and then switch to 50 percent monitor discharge (40L/sec). Despite continuous monitor operations we could still build up our internal water tank supply (@ 1800 L/min) whilst consolidating our hard won gains. We can then switch back to 100% Q and make further gains and so on. We maintain continuous monitor operations with 6% AFFF.

Even using the “Y” for rapid replenishment of a Tender, let alone continuous monitor operations, saves about 3 minutes in refill time. Three minutes is a long time in our line of work! The cost of two “Y’s”, less than $1,000 Aus – 3 parts of bugger all…

The concept of OneQ50 had a flow on effect to operational flexibility. Instead of (the traditional approach) of storing thousands of litres of AFFF in a single fixed storage tank, complemented by 200 litre drums back at the station, it allowed removal of that storage tank and a transition to solely 1000L totes. I now had a valuable – but flexible - resource of foam not bolted to the ground, but able to be deployed anywhere…. What other risks are there in your area of operations that would best be tackled by OneQ50? What other scenarios could we use OneQ50 in to garner maximum operational benefit? What about those airport fuel farms? Wouldn’t it be comforting if we could pre-incident plan exactly how much equipment and consumables are needed to extinguish a particular tank fire and when our “stop time” could occur? It’s always nice to be home for tea on time!

OneQ50 fits this niche quite nicely, thank you very much. In the OneQ50 example using the Panther we need to develop some figures to add to our pre-incident planning in a methodical and pragmatic way.

In Table A: Each column displays the total volume remaining at that given time eg. Column one the first 30 seconds of operation @ 100% using 6% foam while refilling using a vehicle at 40 L/s would result in a remaining total of 7844 L of water (8900L – 2256L expelled + 1200L refill = 7844L remaining) and a total 1196 L of foam remaining (1340L – 144L expelled = 1196L).

If you have a mind to develop the figures a little further you can draw out some fairly startling ones… Now just how much room is left in the fuel tank and what is the capacity of the bund around that fuel farm???

- At 100% Q over 5 minutes you produce 22560L of aspirated AFFF, covering 1550 square metres @ critical application rate (5.5l/s per m square).

- Continuous Ops at 100% with no refill will last 1min 58 secs, covering 613M square @ critical application rate.

- Mk8 will use over 17,000 litres of foam in continuous 6% Ops at 100% monitor Q every hour… That’s a lot of AFFF, how much have you got against your risk versus operational practices??

If you can’t put a blaze out using a sound theoretical calculation, you’ll be hard pressed to put it out. Having said that, “issues” on the day like access, weather and fire conditions, may make life difficult or death easy. However, we must have a place to start from and we don’t want to be expending vital agent to find things out we should have or could have already known.

With a Category 9 airport with the ICAO minimum of 3 ARFF Tenders in a line, using a OneQ50 process and pumping into each other, the third one will run out first. It’s then away to refill or can be replaced by a 4th to maintain water. Local assistance can also plug in to one of four inlets, although their bulk water will probably be significantly less.

You can pump 6% (not yet aspirated) AFFF it tends to be a tad messy – but when it’s “hit the fan” who really cares? You don’t have to relay pump 6% you can just do external foam fill at the last vehicle before the Q vehicle. Saves mess, easier to manage (one refill point) and if you get stuck with low foam where you are inducting it, you can always pump 6% from the vehicles “further behind”. OneQ50 is a practical, low cost, quick get to work method of continuous foam application from a vehicle monitor.

Before you experiment with very expensive pieces of equipment though, have a chat with your fleet engineer to avoid things like over pressurising tanks (we had to leave one lid open during trials). Next time you order a Tender get four inlets built in and a lid that will allow any inflow pressure to be relieved and not crack the tank.

OneQ50 is not currently an ARFF tactic in Australia.

Finally, if your call is to an aircraft in difficult terrain and access is a temporarily insurmountable problem, at least you know it only takes 10 minutes to get HELIFOAM into action…..

Joe Murrell (This paper was published in the Aviation Fire Journal in 2008)

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