International Foam Conference - part II

Published:  05 September, 2013

The first instalment of our highlights of the Fifth International Fire Fighting Foam Conference looked at problems, regulations and requirements. In part II the theme moves towards applications and techniques as well as foam generation and delivery equipment.

The end user and a qualified products list for ARFF use: Simon Webb, UK CAA and ICAO

The proposal for a qualified products list for ARFF goes back to discussions that took place following Copenhagen Airport’s foam conference in 2010 in as well as unanimous support gained over time from the UK Airport Operators’ Association’s Rescue and Fire Fighting Working Group. A public consultation carried out recently also gained unanimous support from end users and Mr Webb stressed the idea for a QPL was not new. ‘This is a voluntary scheme but we recognised how powerful it could be. Category one of the QPL is performance – the bottom line is, is it fit for purpose, is it fit for your purpose.’

An extract from ICAO’s Airport Services Manual was then quoted in order to dispel an oft-misunderstood idea that in ARFF the aim is to extinguish the fire: ‘The critical area is a concept for the rescue of occupants from an aircraft. It differs from other concepts in that instead of attempting to control and extinguish the entire fire it seeks to control only in that area of fire adjacent to the fuselage.’

Mr Webb then commented on firefighting foam Level C proposals that are due to come into force in November 2013 following final ICAO approval. It has taken seven years to get to this stage with the new standard, and as far as evidence of performance Mr Webb emphasised that not only would accredited third party testing be a requirement but also possibly video evidence too.

Picking up on points made earlier in the day Mr Webb said that as well as initial testing CAA would also begin looking at potential batch testing, which could play an important part of post incident investigation activities.

As well as performance the QPL will have criteria around environmental impact – also requiring independent assessment.

The results of the public consultation will be published in due course and Mr Webb was keen to point out the importance of working with a range of partners. ‘But we have to be conscious of two things. Firstly, the people who pay us, the people we regulate, and more importantly the safety of passengers.’

As to what a proposed QPL would look like, in addition to performance data, certification info and possibly a video, there would be an assessment of environmental impact in the form of an eco label – as is used in a range of industries varying from energy, car tyres, aircraft, and electronic goods. ‘All use eco labels in different ways but the common idea is bringing simplicity to an area that is difficult to understand.’

Mr Webb then pointed out the guidance provided by the European Union’s Regulations on Classification, Labelling and Packaging (item 19): ‘To ensure information on hazardous substances is available when they are included in mixtures containing at least one substance that is classified as hazardous, supplemental labelling information should be provided where applicable.’ Mr Webb concluded: ‘So to me that is telling us that what we are proposing here supports the regulations in that area.’

Why we use CAFS – a local fire authority perspective: Adrian Brown, East Sussex FRS and CFOA

East Sussex FRS (UK) has been deploying CAFS for over 10 years and today uses Schmitz One Seven foam systems to deliver class A foam via lay flat hose or hose reels (38mm).   The Service has 18 of 36 appliances with CAFS on board for internal fire fighting and although Mr Brown said he was aware of concerns with kinking and burning through of hose his fire service had not encountered any problems in this regard.

A key issue for using CAFS and promoting its use, said Mr Brown, was firefighter safety. ‘It increases safety of the crews as it has exceptional throw and they don’t have to stand so close to the fire.  The hose is lighter to use, and CAFS makes better use of water resources.  In addition, it provides a good thermal indicator – particularly with deep seated fires – as the hot spots will quickly consume the foam and reveal where we have to tackle the fire.’

As class A foam is used there are fewer environmental concerns from the Environment Agency, and for training purposes fire run-off water is captured in holding tanks.

All crews carry out BA firefighting refresher courses and Mr Brown showed data captured from sensors during such courses. ‘After a two-to-four-second burst of CAFS there is a massive drop in temperature in the fire compartment, and the overall trend is the temperature is going down as the fire is being reduced as a result of direct and indirect gas cooling.’ Sadly, the deaths of two firefighters in 2010 in a high rise in Hampshire highlighted the importance of knowing when to use gas cooling and when to extinguish the fire. ‘One of the things we are teaching our firefighters is that by using CAFS you rapidly see a reduction in temperatures which increases survivability of casualties and makes it is easier to tackle the fire, as we can apply CAFS through the window while the firefighters are going in.’

When East Sussex needed to replace its class B foam it considered whether this could be done in the context of CAFS. ‘We have CAFS on our appliances as well as spare tanks, so we started looking at using CAFS B for our foam strategy. We did some quick calculations and by using a limited amount of foam we worked out we could produce twice as much finished Class B foam using CAFS.’

The FRS weighted evidence from research (primarily ICAO) as well as a recent incident at a local COMAH site and concluded that the use of Class B CAFS would be more efficient than the traditional media delivery systems. ‘And that is something we are now promoting to the rest of UK fire and rescue services.’

An Air Force Out-of-Area Foam Vehicle: Kees Doncker and Tom Manse, Royal Netherlands Air Force

 A growing reliance on helicopters by the Royal Netherlands Air Force combined with new operational procedures that included forward rearming and refuelling in non-friendly areas meant new emergency response requirements had to be implemented.

Initial brainstorming sessions took place in 1998 regarding building a new concept for a vehicle that would be equipped for extrication and fire fighting, had CAFS, was all-terrain, operable from -35 to +65, bombshell resistant, and that enabled the refilling of BA equipment with no external help. And last but not least, it had to be able to carry a crew of three including military and fire fighting equipment.

Nine years later the green light was given to the project and vehicle builder Rosenbauer was brought in to help.

The resulting five operational vehicles each weight 29 tonnes and are designed to fit in a C17 aircraft. An initial 550 horsepower was increased by 100 horsepower with the help of Mercedes in order to achieve 2-minute runway times. The M35 pump produces 25,000 litres at 10 bar and can be used with all types of water. The bumper turret will deliver 2,500 liters per minute at 10 bar (CAFS or otherwise) with a throw range of 70m at full jet (CAFS), 50m spray.

The water tank holds 5,000 litres and the foam tank 300 litres of AFFF. The foam proportioner from Rosenbauer delivers at 1 and % (1% for CAFS). ‘CAFS is one thing we wanted on bard because you can use less water and foam and still get the same results,’ said Mr Manse. Two CAFS systems are on board, one for the turret (2,500 l/m) and one for the fire attack hose(3,000 l/m). The fire attack hose is limited to 60m in length as at 90m the performance of CAFS would deteriorate.

The vehicle carries 4x50 l air bottles at 300 bar to provide the foam water mix. The air is combined with the foam/water mix at the nozzle, just before the final mix leaves the turret. ‘With traditional systems once the foam setting is chosen foam is introduced in the system – with this one the foam doesn’t go into the system until water has pressurised the system, meaning there is less concentrate in the lines and less pollution when the foam setting is picked for precautionary reasons.’

The 4x50 l air bottles can be pressurised by the vehicle itself, the process taking about four hours.

The vehicle was tested in Manston, UK (Royal Air Force ARFF training ground): ‘They did what they call “the road to Basra”, where everyting is set on fire. We usually extinguished everything with an E1 vehicle carrying 12,000 l of water and 7,000 l of foam, with about half the water. We wanted to see how the new vehicle would perform carrying 5,000 l of water. We did it with 2,500 l of water, which demonstrates the power of CAFS. We are confident about its performance.’

Ethanol tank fires – update on ETANKFIRE project: Henry Persson, SP Sweden

The dramatic increase in recent use of ethanol in fuel means that it is being stored and handled in higher quantities. However, ethanol has different properties to petroleum products – it is a polar solvent and the only fire protection recommendations available are based on small scale testing.

ETANKFIRE aims to provide a platform to find out the differences in fire behaviour between gasoline and ethanol on a large scale and look at remedial actions, bearing in mind there are no instances of successful outcomes of fire fighting this type of fuel worldwide.

To date ETANKFIRE has completed one work package in the project involving both small and large-scale free-burning tests.

Two tests have been carried out on an 18 m diameter pool (about 250 m2), using 20,000 l of ethanol, with full details only being released to the project supporters. ‘But what we can say is that with gasoline, the heat radiation decreases over a certain pool diameter, but with ethanol flames it increases, and will be significantly higher than gasoline’ revealed Mr Persson.

Looking at the future the project is focussing on tank fire fighting issues. ‘One work package will look at what kind of test data is available out there, and what kind of experience there is from fighting real ethanol tank fires. Then we plan to run some laboratory-scale tests simulating tank fires – which means a longer preburn time and more fuel. In standard scale tests we quickly get dilution effects of the fuel which gives successful results, and we would like to avoid any significant dilution as will be the case in a real tank fire situation.’

In order to make this research a reality Mr Persson is looking for more partners for the project. Currently there are three partners in ETANKFIRE and two levels of participation are on offer, full and associate level.

Shipboard (marine) fire fighting with AFFF: Dr Holger de Vries, Commander (GNR), German Navy Damage Control School

What is currently taught in western navies relating to damage control and fire fighting has its roots in the experience of the Royal Navy during the Falklands conflict in the 80s. The ships used then were built between the 1960s and 1980s when semiconductors were only just finding their way into ship systems, meaning that the fire fighting procedures in use today are not necessarily fit for purpose as regards both the size and contents of today’s ships.

The standard procedure in the German Navy today for a direct attack involves the use of an Akron nozzle (38mm) working at 230 l/m and 3 % AFFF. If this doesn’t succeed an indirect attack is initiated and the compartment or section is flooded using medium expansion nozzles. To calculate net foam usage the total volume of the compartment is used (without deduction for equipment present in the compartment), and the manufacturers claim a medium expansion foam with an expansion ratio of 50-75. To flood a compartment therefore of 2,000m3 around 40-60 canisters would be necessary, which would take around 67-100 minutes. ‘The problem however is with AFFF you have 50% drain time of 8-15 minutes, so we have to race against the degradation of foam over time.’

After contacting a number of other navies it soon became clear that there was a general lack of awareness that there was an issue with drainage times, and therefore no data for suggested solutions.

This led Dr de Vries to carry out some tests in a demilitarised frigate on the Baltic sea. The frigate’s 500m3 turbine room with a height of around five metres took around 20 minutes to flood, which raised enough concerns to seek further data. Consequently, outside help from another branch of the German military conducted experiments inside a 160m3 tower.

Thirty trials were carried out and the results confirmed what was suspected: that the race against AFFF degradation would be lost with existing operating procedures.

The experiments concluded that in order to be on the safe side with AFFF, calculations needed to be carried out with an expansion rate of 25 (giving a safety factor of approximately 2), and that per 200m3 volume of space at least one medium expansion nozzle flowing 400 l/min should be used.

This approach took into consideration the temperatures at which steel begins to degrade, where the critical flooding time when there is a fully involved fire is in the order of 10-15 minutes. ‘So presumably if you have to play around for 30 minutes you have not one big ship, but two small ships.’

Also taken into consideration was that in marine environments putting the water on the fire is only half the story, ‘Because you can only pump in as much as you can safely get out of the ship. So we also calculated how many cubic metres the ship has to be able to pump out.’

Biodegradators, toxicology and biomonitoring of AFFF short-chain chemistry: Dr Steve Korzeniowski, DuPont, USA

After a short introduction Dr Korzeniowski highlighted that although industry was moving towards short chains and more sustainable products and therefore away from potentially PBT compounds, there was no current solution in the form of a molecule or organism that would enable the foam industry to overcome the persistent nature of the fluorinated compounds used in AFFF.

A lot of work has gone into what happens to raw materials in the environment to understand what they become in terms of toxicology and environmental fate and effects.

Dr Korzeniowski presented a chemical chart that showed how these substances all converge towards a 6:2 Fluorotelomer alcohol biodegradation pathway, ultimately making the same molecules in the environment. ‘A substantial fraction of the 6:2 fluorotelomer sulphonate (6:2 FTS) fluorosurfactant backbone appears to become a non extractable bioresidue in activated sludge and possibly in soil and sediment as well.’ In activated sludge the 6:2 FTS degrades only partially (about 3%) and forms a small amount of  C6 acid – PFHxA, perfluorohexanoic acid (about 1%) and neither PFOA nor PFOS.

The C6 chemistry, either 6:2 FTS or PFHxA, has been studied over the past several years in support of the US EPA 2010/15 PFOA Stewardship Program as the industry transitions away from the longer chain chemicals. A wide range of media in the environment including aquatic and mammalian systems have been studied. ‘As a supplier of fluorosurfactants, my job has been to supply products that in the end are sustainable to the industry and the environment  and continue to provide fire fighting capability and performance for our customers.’

An important aspect is what harm the fluorochemical products and degradation products do to mammalian and environmental systems. Industry is often asked by environment agencies and others whether short chained pefluoroalkyl acids remain in humans and other mammalian systems for as long as long-chained ones do (PFHxS, PFOA, PFOS). The answer is 'no', emphasised Dr Korzeniowski, highlighting some significant work carried out in the last five years on short-chain chemistry.

A 2010 Swedish study on ski wax technicians  monitored their blood for numerous fluorinated species including PFHxA. The peer-reviewed published study indicated PFHxA has an apparent a half life of less than 28 days. 

This compares to three to four years with certain longer chain compounds. ‘And what the author of that study said is that when the technicians stopped doing their work, waxing the skis, the PFHxA decreases to below the limit of detection (

Fluorotelomer sulphonate mammalian toxicology data that had been presented at previous Reebok conferences showed how toxicology testing in mammalian systems exhibited favourable results. Aquatic toxicology data presented were also quite favourable for 6:2 FTS. The basic conclusion is that it is not classified for aquatic toxicity and is not bioaccumulative. The work done with Rainbow trout, Algae and Daphnia – all key to regulators – is that this chemistry is not classified as PBT.  The bioaccumulation and toxicity profile of the new chemistry is significantly different than historical long chain chemicals.  Short chain Fluorotelomer AFFF agents do not become PFOS. DuPont and others have spent considerable effort doing the work and publishing it in peer-reviewed journals.

‘We have worked to create sustainable high performance products. However, what is going to be acceptable in five years’ time we as an industry are going to figure out with you.’

Silvara, a Newtonian eco-efficient foam: Manuel Acuña, VS Focum, Spain

Foam manufacturers are constantly up against the challenge of mixing the right type of permitted ingredients to get the best fire fighting results whilst at the same time respecting environmental regulations.

Silvara is the result of work carried out to create a fluorine-free product and its chemistry is fundamentally different to existing fluorine-free products on the market. It is generally used at 1% as opposed to 3/6%. It is a Newtonian foam as opposed to one containing pseudoplastics, which means it has low viscosity properties. It extinguishes fires through the interaction of its ingredients as opposed to through the fluidity and water-holding properties of traditional foam.

In terms of accreditation, Silvara has attained EN-1568-3 with Class IB at 1%, EN-1568-1 at 3% (medium expansion), and ICAO level B at 3%. ‘We concluded we don’t need the pseudoplastic element to pass part 1, 2 and 3 of the EN standard, but we do need it to pass part 4 against polar solvent fires.’

Next, Mr Acuña contrasted Silvara and another fluorine free foam with AFFF, which revealed ‘a lot of surprises’. The main issues revolved around spray extinction and oleophobicity – the latter relating to fuel contamination and foam blanket sealing.

For the spray extinction test a simple experiment was set up with a 1m diameter pan and an application of 6 l/min/m2. The fuels tested were heptane, gasoline and kerosene, and the foams used were Silvara 1, AFFF 1%, a fluorine-free foam (3%), Silvara 13 (1x3) (1%), and AFFF-AR 1x3 (1%).

AFFF foam got the best results and surprisingly the fluorine-free foam did not extinguish or control heptane or gasoline, but did well with kerosene. ‘The conclusion is that AFFF spray extinction is easy and reliable – but with fluorine-free foam it depends on the fuel type.’

The second test involved measuring the contamination of the foam. 75cc of solution were mixed in a 500cc plastic bottle of mineral water with  20cc of fuel, and the mixture shaken to form foam.

The mix was then poured into a 22cm pan, and a 4cm diameter cap with fuel placed in the centre. The fuel cap was then ignited, and the time it takes for the foam to be destroyed completely measured. The foams tested were AFFF, AFFF/AR, three fluorine-free foams, one class A foam, and one forest retardant. ‘Again AFFF had the best result and the worst was class A and forest retardant. Silvara was not the best but the results are noteworthy.’ The performance of some of the fluorine-free foams also varied dramatically depending on the fuel used.

Another experiment designed to measure fuel evaporation with a foam blanket over 45 minutes revealed some interesting results. Fluorine-free foam struggled with gasoline vapour but performed much better with heptane, while AFFF was consistently good and Silvara not far behind.

Moving to real fire scenarios Mr Acuña carried out a total of 90 tests using a 1m pan, five foam products (AFFF, AFFF-AR, FFF, Silvara 1 and Silvara 13) and a variety of aspirated and non-aspirated systems and application rates, with heptane, gasoline, and kerosene Jet. ‘The conclusion was that once again AFFF was the best in both low application rates and forceful application.’

AFFF and Silvara 1 were then compared using four pan sizes (largest 7.06m2), heptane fuel, and measurements taken for control (90% and 99%) and extinction, at 2.5 l/m, application 1m and preburn time 1m. While Silvara’s control times were comparable with AFFF, Silvara 1 failed to extinguish the fire with the largest pan size. The conclusion was that the larger the fire the bigger the performance gap between fluorine-free foam and AFFF.

The results of a large scale experiment using Silvara (3%) with 5,000 l of Kerosene Jet A-1 in a 164 sqm pan and two 200 l/min. nozzles at 2.4 l/min/m2 revealed an extinction of 7.2 minutes: ‘Not so good and perhaps the mistake was choosing two nozzles. It may have been better to choose only 1 nozzle running at 400 l/m. But in the end Silvara put the fire out.’

VS Focum’s next objective is to achieve 1x3 certification. ‘To conclude, we have had to say goodbye to PFOS and PFOA and we are now moving to C6 chemistry.

What is next? Perhaps in the future fluorine will be forbidden, but for now we have to use all our imagination and hard work towards achieving the best results with fluorine-free products.’

Water treatment of fire fighting runoff – on a commercial scale. Romain Severac, DuPont, France, Dr Martial Pabon, DuPont Geneva

Dr Severac’s project involved developing a mobile treatment system for fire fighting foam run-off water that would minimise the cost of disposal via the use of traditional waste water treatment plants and specialist incinerators.

The cost (without counting logistics) of incineration varies from country to country.  For example, in France it is around 0.77 Euro cent per litre whereas in Australia it can be as high as $13 per litre.

The fire fighting foam run-off water contains large particles (suspended matter) which have to be removed before the water treatment process can start. The treatments considered for this process include filtration, centrifugation, coagulation-flocculation, and electrocoagulation.

The next stage involves the removal of fluorosurfactants and hydrocarbon surfactants, additives and polymers – processes considered included absorption, membranes, advanced oxidation, and liquid-liquid extraction.

Each method was compared via a number of parameters such as cost, efficiency and mobility (ie the system has to be portable in order to allow ease of movement between locations). The methods chosen for pre-treatment were coagulation and flocculation, and electrocoagulation. The methods selected for actual treatment were electrocoagulation and reverse osmosis. Research was undertaken in conjunction with Ecole Central de Paris, at both the laboratory and pilot scale to demonstrate such a system could work.

Concentrating on electrocoagulation and reverse osmosis, Dr Severac said, ‘By using these two methods in combination, 100% initial waste could be reduced to 0.1 to 0.2% in volume for transport and incineration, and the rest sent directly to a waste water treatment plant. If you take solution containing 140ppm from one of our fluorosurfactants at the end of the process, its content is below the limit of detection capability, which is below 0.1ppm.’ The pilot system devised can treat 0.5 to 4m3 of water per hour. Dr Severac demonstrated two systems that are in use on an industrial scale using similar methods: one is used by wine growers using reverse osmosis to treat water contaminated by pesticides, and the other a mobile system used by Veolia that can produce up to 300m3 of deionized water per hour.

A cost analysis comparing incineration, coagulation/absorption, and electrocoagulation/reverse osmosis revealed two things. That incineration was by far the most expensive option, and that even if the initial capital investment of the alternatives was significant, return on investment was rapid. Secondly, long-term electrocoagulation/reverse osmosis was the most cost-effective option. ‘In conclusion, the on-site treatment of fire fighting foam run-off water can lead to significant short-term savings. There are limited options available and they depend on mobility, treatment flow, and volume per year/month.

‘You can select a system now, and it can be rented from Veolia, or you can have one permanently installed in your plant.’

Large foam applications – practical considerations: Gary Douthwaite, Hawkes Fire, UK

To get the audience thinking about emergency planning Mr Douthwaite invited delegates to consider a situation: you are at home, at 3am, with your wife and two teenage daughters, and you hear a crash and loud voices. You go down and see three men in ski masks rifling through the premises: what actions would you take? The exercise highlighted the differences between an emotional and planned reaction, illustrating how having a plan would result in a better response. ‘Now let’s change the scenario slightly: similar time, this time you are with your sons who are both rugby players and black belt experts. You look down and see two five-foot burglars weighting eight stones each. What would your actions be then?’

With delegates thinking along the lines of risk assessments and response, Mr Douthwaite moved on to incidents involving storage tanks – in particular incidents requiring intervention by emergency responders (ie fixed systems rendered unusuable). ‘You have to deploy over-the-top fire fighting methodology. You are looking at major hydrofoam monitors. For a successful outcome you are looking at adequate water supplies, foam supplies, and logistical support to ensure a long protracted incident can be fed.’

Crucial also is training, exercising, and both local and national mutual aid agreements. ‘If you have all those factors in place you may be lucky and have a successful outcome.’

Too often major equipment is purchased and after an intial period of training it is stored away and forgotten about. ‘And what generally happens is that when it is required the tyres will be flat, the wheels seized and the kit won't work.’

After showing how response to these incidents can be compromised by a lack of planning, Mr Douthwaite showed how equipment (eg pump) requirements within emergency plans had to be scenario specific. In the example of the house breaking, a defensive strategy would be chosen with the teenage daughters’ instance, whilst an offensive strategy would be chosen with the black belt sons. ‘It is the same with fire fighting. If you have a generic plan, you end up with a "shall we" or "shan’t we" approach. And you will have a plan, but with lots of deviations and those deviations may not be thought out as well as they could be.’

A number of difficulties and potential problems associated with using appropriately-sized fire fighting equipment for large scale incidents were showcased – particularly when used without a well thought out plan. ‘The largest fire surface area I’ve been to so far was in ICI Wilton in 1995, when 20,000 tonnes of polypropylene chips were on fire. We used 16 million litres of water in 11 fires to bring that fire under control – not to a conclusion. There were somewhere in the region of 45 fire appliances and 200 firefighters not including ICI internal emergency response. The fire water runoff was unbelievable, we were wading knee deep in water.’

Considerations should include high volume pump hose deployment over long distances requiring multiple runs as well as a retrieval system post event. As for foam supplies, responders are probably looking at 8,000 gallons per minute, using one intermediate bulk container (IBC) per minute. ‘If you are going to do a 60-minute attack you are going to need three flat-backed trailers each with IBCs on. The amount of fork lift truck manoeuvring and logistics is worth exercising in its own right. Foam tankers are specifically designed for this, and one with 20,000 litres at 3% would give you more than 20 minutes supply – but at 1% it is one hour’s supply which is even better.’

Finishing his presentation Gary Douthwaite asked delegates with a response responsibility at a storage tank facility to raise their hands if they had carried out an exercise with an HVP monitor in the last six months. ‘One guy. Are we planning to succeed or fail?

Environmental profiling of fire fighting foams – defining ‘green’: Thomas Leonhardt, Tyco, Germany

Stating that to define ‘green’ was attempting the impossible, Mr Leonhardt admitted that he would be disappointing the delegates. ‘Green’ is understood to mean harmless and environmentally benign, but it has not been substantiated or defined. ‘It’s a rarely scientifically corroborated term with  no set of parameters so we don’t know what it means to be benign. Even if we had parameters we would have to know where the threshold is, a line in the sand under which something is benign and over which it is not.’

Mr Leonhardt’s aim was to develop a system that resulted in a gradation scheme for foam. The first step was to identify the parameters i.e. what to test for to see how green a foam is, followed by pulling that into a scheme that gradated and evaluated the results.

Firstly some parameters were identified that described the impact of foam at a typical incident – so exposure to firefighters, followed by exposure to waterways, sewage systems, and soil. This included toxicity to mammals, as well as aquatic and soil impact as shown by effects on earthworms and plant germination. Finally, P, B and T were also covered.

These parameters, admitted Mr Leonhardt, are arguable but the intention was to narrow them down to a practical number that wouldn’t inflate the cost of testing whilst still providing a good ideal of the overall impact of a foam agent on the environment.

In order to rank and test the parameters the project adopted the Global Harmonised System for the classification and labelling of chemicals, which is steadily being adopted globally, and this framework provides limiting values and classification for the parameters identified. ‘The beauty of using or applying the GHS is that you get a classification, and according to GHS the highest category number equates to the lowest risk.’

The next challenge was evaluating fire performance – a much more complex and difficult area, considering the number of international performance standards in existence. ‘And all of them use different set ups and hardware, fuels, application rates etc. So that is going to be a tough thing to implement into a global or commonly acceptable scheme.’

It was decided to use EN 1568 (2000 part 3) not because Mr Leonhardt is European but because that is one of the standards that provides ratings, which would lend itself to a gradation scheme. ‘Here there are ratings for burnback and fire performance and we directly converted those into factors.’

After presenting a reduced version (to fit the screen) of such a table, Mr Leonhardt pointed at a sub-table carrying proportioning ratios of the foam, as well as percentage solids in the concentrate. ‘We did a simplified approach so you can either unfold the formulae and use all the ingredients  and it calculates the value for your foam or, another way for formulas that aren’t common knowledge, you type in the percentage solids.’

All the different sections (toxicology, environmental impact and performance) contribute to a final rating.

‘This means we don’t need to develop new testing schemes, and we don’t suffer from the influence of national or regional legislation. The other advantage we see is it correlates the toxicology and environmental footprint with fire performance – because the fire performance defines how much of the agent you actually need to put out a particular size of fire. So the effectiveness of the agent contributes to the overall evaluation of how green an agent can be.’

Concluding, it was admitted that some questions still needed answering, for example how to weight performance against toxicological and environmental impact. But the system allows for the factors to be changed: ‘The bigger problem is how to pull in other international standards, as not all foams on the planet are tested to EN 1568. One way is to use extinguishing and burnback times, as they are mostly recorded by other standards as well. The alternative is to developed a new standard to test all foams across the board, which would be more difficult.’

Comparative testing of large mobile monitors: Robert Hut, HyTrans Systems, The Netherlands

A direct comparison test was decided upon when it was noticed that the differences in claims of suppliers regarding their monitors’ throw didn’t always match experiences in the field. ‘Interior testing of monitors with a throw of 100-150m is difficult so we thought the best way to compare them was to do a direct comparison test – by putting them side to side the wind conditions would be identical.’

Hytrans Systems, which manufacturers Mobile Water Supply systems including hydraulic submersible pumps and high volume pumps, happened to have three monitors on site at the same time, each with a flow of 8-12,000 gallons per minute. ‘We also had two 8,000 gallon pumps so we thought, let’s play with water. And the weather is nice.’

The test, admitted Mr Hut, was not meant to be in-depth and as such only two brands were compared.

Background theoretical data was obtained in the form of a bullet travelling in a vacuum, and Mr Hut pointed out that it so happened that the throw from the monitors matched the data of the bullet theory very closely (with no wind).

A 30-degree elevation was chosen as it is generally accepted that the best reach is attained with 30-40 degree elevation depending on conditions.

Mr Hut explained in detail some of the problematic issues regarding this type of comparison test in terms of measuring flow and pressure. Often the pressure readings of a monitor are positioned near the nozzle, where some of the pressure has already been converted to speed. ‘The water is already accelerating at the point where you are measuring pressure, so you may be reading 7 bar, but in reality if you subtracted the speed component it would be 8 bar. And then again if you’ve already had some bends you would probably see with the monitor that to get a 7-bar reading you would need to arrive with 9 bar pressure at the monitor inlet. And that is something that is often forgotten, and of course if you miss two bar you will not get the expected performance.’

Some supplier brochures assume backwind, which could be thought of as ‘cheating’ but this reflects practical usage as a monitor would always be used in that position. ‘However from the data sheets it is not always clear whether reference to “pressure at the monitor” refers to pressure at the nozzle or at the inlet.’ End users are probably assuming they have to deliver at a certain pressure, but that is not the same as the pressure at the monitor.

Variation in throw measurements was another issue. Some throw measurements state that the last drop is the distance of the throw. A European standard states throw is the last drop minus 10% of the throw. ‘But most important is where the majority of the water goes to because usually you want to fill the tank with water foam mix.’

For the test two Hydrosub 1200 pumps were used, each with a capacity of 30,000 l/m (approx 8,000 gallons). Three big monitors were laid side by side, with different piping (8/10/12), which was not envisaged to impact the outcome, ‘Because what we are comparing is nozzle pressure – we make nozzle pressure the same and flow the same, so basically comparing the nozzle part.’

Accurate calibrated flow meters and pressure meters were used, with flows of 6,000 gallons per minute as a maximum, with a pressure of 7 bar at the nozzle. Flow adjustments were made at the nozzle to ensure the same flow and pressure.

As for the results, all monitors achieved over 100m with little wind, but two had a 10m difference in throw. One of these two had been previously been tested by Hytrans with back wind and achieved over 160m. ‘Looking at the figures if you are working at 7 or 8 bar, 100-120m is realistic with no wind.’

Using a full jet nozzle is generally thought to provide up to 10% better throw, but this was not tested. With foam, it is common to see statements warning of a 5-20% reduction in throw, said Mr Hut.

The definition of ‘throw’ is often absent in tenders for such equipment, queried Mr Hut, but if 'throw' is in the criteria, the definition should also be there. ‘If the monitor is intended to fit on the edge of the bund, and it is 120m to the tank, you should not define the throw to be 120m. You might think that it should instead be 150m to reach the centre, but that is not correct either because there is the height effect as well. In the case of a tank 120m away you may need a reach of 170m. If you defined 120m you would only get cooling on the front part of the tank.’

Concluding, Mr Hut said that, when choosing a monitor, specifiers should consider the most important performance characteristics of the monitor. ‘Throw is probably the main criteria but you should also check the definition of pressure and throw. And it would be nice to test it, although it is difficult to do a repeatable test under specific wind conditions.’

To read Part I click here.

  • Operation Florian

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