FAQs

Aqueous Film-Forming Foams (AFFFs) effectively extinguish and secure liquid hydrocarbon fires by the following actions:

• Film-forming – the foam forms an aqueous film across the surface of the fire to quickly cut off the oxygen supply and effectively knock down the flames.
• Low surface tension – as the liquid drains from the foam, the surface tension reduces to ensure the foam floats on top of the surface of the liquid fuel.
• Foam expansion – the foam cools the fuel’s surface and creates a stable blanket to suppress the release of flammable vapours.
• Resealing – if the blanket is broken by personnel or equipment, the foam quickly reseals to minimise the risk of re-ignition.

Alcohol Resistant Aqueous Film-Forming Foams effectively extinguish and secure liquid hydrocarbon and polar solvent fires by the following actions:

• Film-forming – the foam forms an aqueous film across the surface of the fire to quickly cut off the oxygen supply and effectively knock down the flames.
• Low surface tension – as the liquid drains from the foam, the surface tension reduces to ensure the foam floats on top of the surface of the liquid fuel.
• Foam expansion – the foam cools the fuel’s surface and creates a stable blanket to suppress the release of flammable vapours.
• Resealing – if the blanket is broken by personnel or equipment, the foam quickly reseals to minimise the risk of re-ignition.
• Membrane forming – in fires involving polar solvents, an insoluble polymer membrane is formed to protect the foam blanket from the solvent.

Fire fighting foam concentrates are best stored as supplied in original, unopened containers.

They are also suitable for storage in containers and tanks manufactured from:

• Stainless steel (Type 304L or 316L)
• High density cross-linked polyethylene
• FRP (vinyl ester epoxy resin only)

To prolong the shelf life of any foam concentrate, do not expose to temperature extremes and prevent contamination from foreign materials.

Foam expansion properties will vary depending on several factors including:

• Using salt or fresh water
• Water hardness
• Equipment characteristics
• Equipment flow rate

For example, aspirating devices will produce typical expansion ratios of between 6:1 and 10:1 and non-aspirating devices between 2:1 and 4:1.

Always check your equipment’s operation manual for guidance.

Our foams are available in the following pack sizes:

20 litre, 25 litre, 200 litre, 1000 litre containers and bulk tanks.

Fire Fighting Foams usually have a very long shelf life, provided they are kept within the manufacturers guidelines and temperature limits and are stored in the original and unopened shipping containers. For example, a shelf life of 10–20 years can be expected for AFFF-LF and AFFF concentrates, if stored correctly. 

For opened containers, this shelf life can be compromised due to factors out-with manufacturers control such as dilution, contamination and extremes of temperature.

Please refer to Safety Data Sheet for preferred storage conditions and guidance.

Most produced foams can be safely disposed of in biological waste water treatment systems. However, it is always best to check the individual product's Safety Data Sheet for information regarding disposal.

Our laboratory tests show that our Aqueous Film Forming Foam concentrates are compatible with other high quality AFFFs and ABC and BC fire fighting powders.

However, if you mix C6 and non-C6 foams, you will no longer be C6 compliant.

As recommended by NFPA 11: 2021, we would advise that a batch compatibility test is performed before mixing foam concentrates from different manufacturers.

For further information, please see our Compatibility page.

Trouble-shooting on foam systems falls into three main categories:

• Storage
• Proportioning
• Foam making and delivery

Problems in the above areas which result in poor foam quality will be indicated by your foam testing procedures, either by yourself using Foam Test Kits or testing done by an external Foam Laboratory.

Problems which result in mechanical and electrical failures would normally result in no foam delivery. Investigations should then be made on the following:

• Automatic foam concentrate supply valves
• Mechanical pump performance of the foam concentrate pump
• Electric circuits which control the pump and automatic valves

Overall System Checking

Very often a foam system is part of an overall fire detection and extinguishing system. Under these circumstances, the entire system must be checked out at the commissioning stage and at regular intervals as part of a routine maintenance programme.

The following is a checklist summarising the points that should be examined:

System Checklist

Detectors

• Each detector trips system
• Each manual pull box trips system
• Supervisory system stable
• Imposed faults create the correct alarms

Actuators

• Trip Valve
• • Water
  • Concentrate
  • Solution

Prime Movers

• Water pump or other water source
• • Relief valve operational at correct setting
  • Control Panel functional

• Foam Concentrate Pumps

• • Relief valve operational at correct setting
  • Control Panel functional

Quality fire fighting foam concentrates exhibit excellent storage characteristics.  For example, most AFFF manufacturers offer at least a 10 year life for products stored in original and unopened containers. 

However a foam's performance can be compromised by:

For this reason, international standards such as NFPA 11: 2021 and BS EN 13565-2: 2018 recommend that stored foam concentrates should be tested on "at least annually."

As recommended by international standards NFPA 11: 2021 and BS.EN 13565-2:2018, foam concentrates should be inspected and tested at least annually as part of your fire fighting foam maintenance programme. 

Oil Technics Limited offers a worldwide foam testing service and inhouse foam testing training. For further details, please contact us or visit our foam testing webpage.

The purpose of a Foam Concentrate Test Report is to evaluate if the sample tested is in satisfactory condition and most importantly is within the manufacturer's specification. 

Each Foam Concentrate Test Report offers analysis of 10 key features:

For each report, provide at least:

• 1 Litre of Foam Concentrate

Samples should ideally be provided in clean tightly sealed polythene bottles and be labelled with the following information:

• Company Name
  
• Order Reference / PO Number
• Type of Foam Concentrate
• Concentration
• Foam Manufacturer
• Sample source
• Sample location point
• Date of sample location

If you would like to receive free sample bottles and labels, please contact us.

The Foam Concentrate sample should be representative of the stored product.

The three sample procedures most frequently used are:

Single Sample

• Circulate the stored product to obtain a single homogeneous sample.

 Two Samples

• Take a sample from the top and bottom of the stored product and composite the samples into a single unit.

 Three Samples

• Take a top, middle and bottom sample and composite into a single unit.

NB: It is important that sludge, sediment, rust, scale, etc is removed before collection of the bottom sample. To do this, draw off at least 5−10 Litres of product before taking a sample.

Samples are visually examined for visible sediment, concentrate colour and whether it is homogeneous. 

• Visible sediment indicates contamination (possibly due to poor storage conditions).
• Colour change, when compared to the manufacturer’s specification, could indicate contamination by a different foam type or concentrate degradation.
• Non homogeneous liquid suggests a serious failure.

Change in Specific Gravity, when compared to the manufacturer’s specification, indicates whether a foam concentrate has been diluted or in temperate climates concentrated due to losses caused by evaporation.

Change in pH, when compared to the manufacturer’s specification, can be caused by one or all of the following:

• Product degradation
• Product contamination
• Biological decomposition

pH testing is carried out in accordance with BS EN 1568 1-4: 2018, Part 7.

Surface Tension indicates how well the foam will “spread” across the surface of a fire. Surface Tension is measured using a Torsion Balance measure.

Change in Surface Tension, when compared to the manufacturer’s specification, can effect performance.

Surface tension testing is carried out in accordance with ASTM D-971: 2012 and ISO 304: 1985..

Sediment is tested using a Centrifuge tube “spin”. Sediment can arise from:

• Degradation
• Contamination
• Mixture of incompatible foams

Typically AFFF’s should exhibit less than 0.1% and Protein based foams no greater than 0.5%.

Reduced viscosity, when compared to the manufacturer’s specification, can be a sign of dilution and/or degradation.

Excessively high viscosity can effect induction strength and performance.

Foam concentrates are placed in a freezer and the temperature taken at transition point between crystal and homogeneous liquid phase.

Changes in Freeze Point, when compared to the manufacturer’s specification, can indicate dilution or contamination of Foam Concentrate.

Drainage Time is the speed at which water drains from a foam and is therefore a critical measure of a Foam’s stability.

Foam Test laboratories measure the 25% Drainage Time (sometimes referred to as Quarter Drainage). This is the time taken for 25% of the water content to drain from a foam.

Change in 25% drainage, when compared to the manufacturer’s specification, can effect performance.

25% Drainage testing is carried out in accordance with BS EN 1568 1-4: 2018, Annex G and NFPA 11: 2021, Annex D.

Expansion is the ratio of foam produced to the volume of solution used to generate that foam, ie Expansion = Volume of Foam / Volume of Foam Solution.

• An Expansion Ratio of 5 to 1 would indicate that 1 litre of foam solution, once aerated, would fill a 5 litre container with expanded foam mass.
• An Expansion Ratio of 7 to 1 would indicate that 100 litres of foam solution, once aerated, would make 700 litres of expanded foam mass.

Expansion is related not only to the Foam concentrate but to temperature, water quality, foam making equipment and test procedure. For these reasons, the temperature of the Foam Concentrate water, air and Foam Solution is recorded.

Similarly, standard Foam making equipment and collection procedure should always be used in order to compare results obtained.

Change in Expansion, when compared to the manufacturer’s specification, can effect performance.

Expansion testing is carried out in accordance with BS EN 1568 1-4: 2018, Annex G and NFPA 11: 2021, Annex D.

Fire Extinguishment properties are tested by igniting a quantity of fuel (heptane or alcohol) in a test pan and applying a quantity of foam after a set time. If the fire is not extinguished within a set time, the foam has failed.

Burnback performance is measured using a rectangular test pan filled with a quantity of heptane. This pan is divided – 90% of the surface has foam applied to it and the remaining 10% surface is ignited. After a set time, the divider is removed and the progress of the fire’s spread is measured and timed. The foam has passed if the flames have not progressed to a set percentage of the surface area after a set time.

Foam proportioning systems are reliable and are subject to regular rigorous inspections and maintenance.

However,  international standards such as NFPA11: 2021 and BS EN 13565-2: 2018 recommend that: 

"At least annually, all foam systems shall be thoroughly inspected and tested for correct operation."

NFPA 11, 2021 Edition 13.2.1

Testing regularly helps ensure your foam is correctly proportioned and therefore fit for purpose.

NFPA 11: 2021, Paragraph 12.6.5 states:

“The foam concentrate induction rate of a proportioner ... shall be within minus 0 percent to plus 30 percent of the manufacturer’s listed concentrations, or plus 1 percentage point, whichever is less." 

Paragraph 13.2.1 further states:

"At least annually, all foam systems shall be thoroughly inspected and checked tested for correct operation."

For further information or to buy NFPA 11: 2021 online, visit the NFPA website.

The purpose of a Produced Foam Test Report is to determine the suitability and accuracy of a foam system's proportioning / induction equipment. 

Each Produced Foam Test Report shows the calculated percentage induction measured using the sample provided. This result is compared against the "acceptable ranges for proportioning percentage " stated in international foam standards NFPA 11: 2021 and BS EN 13565-1: 2019.

The two recognised commissioning standards for produced foam are:

• NFPA 11: 2021 Edition, Paragraph 12.6
• BS EN 13565-1: 2019, Section 5.3

The “acceptable ranges for proportioning percentage” stated in these standards are:

If your produced foam falls outwith these ranges as part of your foam testing protocols, it would be considered a fail; your foam systems proportioning and induction equipment will require recalibration.

"The foam concentrate induction rate of a proportioner... shall be within minus 0 percent to plus 30 percent of the manufacturer’s listed concentrations, or plus 1 percentage point, whichever is less. "

NFPA 11: 2021, Paragraph 12.6.5

Produced or Expanded Foam samples should represent as closely as possible the foam reaching the designated discharge area. 

Collecting samples from nozzles, monitors and overhead sprinklers:

• Collect sample from point of impact in the discharge area.

 Collecting samples from Foam Pourers:

• Insert sample container into the edge of produced foam stream and take sample.

 Practical Points:

• Before taking a sample, activate the foam system long enough to remove standing columns of water (which otherwise would contribute to a dilute produced foam sample).
• Sample when the system is in equilibrium.

This is a method for calculating the actual concentration of a sample of produced foam and is used to test the accuracy of the proportioning equipment used. 

To do this test you need samples of:

• Produced Foam
• Foam Concentrate used
• Induction Water used 

Note: it is important to use the actual induction water used (the refractive index of sea water, for example, is highly variable). 

Test Procedure

Using a refractometer, the Refractive Index (RI) of the Produced Foam sample is compared with the Refractive Index of known foam solutions. 

It is advisable to make known foam solutions (using the Foam Concentrate) which are above and below the Produced Foam concentration. For example, if testing a 3% Produced Foam sample, take the Refractive Index of:

• Induction Water
• Foam Concentrate/Water Solutions at 2, 3, 4 and 5%

Results

A Refractive Index vs. Concentration Curve is then drawn using the RI of the Foam Solutions, where the % Foam Solution is the Vertical Axis and the RI is the Horizontal Axis.

Using the RI of the Produced Foam Sample, the point at which it meets the pre-calculated curve is plotted using the known foam solutions. 

The percentage concentration of the Produced Foam sample is gained by reading the Vertical Axis relating to the Produced Foams RI.

For each test, provide at least:

• 1 Litre of Foam Concentrate
• 1 Litre of Induction water
• 0.5 Litre of Produced Foam 

Samples should ideally be provided in clean tightly sealed polythene bottles and be labelled with the following information:

• Type of Foam Concentrate/Produced Foam e.g. 3% AFFF-LF
• Name of Company
• Date of Sample Taken
• Sample Source 

If you would like to receive free sample bottles and labels, please click here.

Oil Technics provides an in-house Training Course on Produced Foam Testing. This course provides extensive technical background and hands-on experience in all aspects of Foam Testing and, on completion, attendees are presented with a Certificate of Competency.  The course lasts approximately half a day. 

For further information on pricing and availability, please contact us.

Foam concentrates are tested by manufacturers to meet Internationally recognised extinguishment, burnback and proportioning standards.

The three most widely recognised tests are:

These are critical application tests in that foam concentrates are tested to the minimum application rate required to extinguish a fire: a quality foam supplier will supply foam concentrates that meet at least one of these standards. 

For further information, please see our International Standards page.

Foam concentrates are tested by manufacturers to meet Internationally recognised standards that evaluate extinguishment, burnback and proportioning. For further information, please see our International Standards page.

It is mandatory that all foams used in civilian airports must be approved to ICAO Level A, ICAO Level B or ICAO Level C standard.

ICAO Level B

In order to obtain ICAO Level B certification the foam concentrate, once proportioned correctly, must extinguish a 4.5m² hydrocarbon fire within the given specifications (see table below).

The application rate for the ICAO Level B test is 2.5 L/min/m².

ICAO Level C

In order to obtain ICAO Level C certification the foam concentrate, once proportioned correctly, must extinguish a 7.32m² hydrocarbon fire within the given specifications (see table below).

The application rate for the ICAO Level C test is 1.75 L/min/m².

ICAO Level C test has been designed to permit substantially reduced quantities of foam and water to available on fire trucks (for further information, please refer to the OTAC document on Rescue and Fire-Fighting Management of Extinguishing Agents here.)

Comparison of Test Protocol

ICAO Level C places increased emphasis on:

• Impacts of fluctuating water pressure
• ARFF vehicle monitor application rates, i.e. regular produced foam testing.

Useful links

• OTAC document: "Rescue and Fire-Fighting Management of Extinguishing Agents" (PDF)
• Asia Pacific Fire Magazine article: "Proposed ICAO Fire Test Changes Compromise Fires Safety" (PDF)

IMO stands for International Maritime Organization (IMO). It has introduced two testing standards (IMO MSC.1/Circ 1312 and MSC Circ.670) to ensure that foam used at sea is fit for purpose and takes into consideration performance with sea water induction and temperature conditioning (accelerated ageing). The standards are now required by many maritime administrations and classification bodies for foam concentrates to be used on board ships in international waters. This may lead to an administration/classification body stipulating the use of an IMO compliant foam and rejecting the use of a non-compliant fire-fighting foam on board ships.

The IMO standards have arisen as part of the implementation of the SOLAS Convention (Safety of Life at Sea). 

The following Aberdeen Foam concentrates have been tested by an independent laboratory and meet the requirements of IMO MSC.1/Circ 1312:

BOD/COD is a laboratory test that can be performed to determine the biodegradability of a chemical in the aqueous environment.

It is done by measuring the mass of oxygen a chemical removes from water. A reduction of oxygen in the marine environment can be a potential problem as any removal of oxygen from water may adversely affect or even kill fish and other marine life.

The two parts of BOD/COD are:

1) Biochemical Oxygen Demand (BOD): the amount of dissolved oxygen used by micro-organisms to naturally break down (oxidise) organic material in water. Measurements are taken at certain temperature (usually 20ºC) over a specific time period (usually 5 and/or 20 days). Results are given as mgO2/l.

2) Chemical Oxygen Demand (COD): a measure of the total oxygen consumption of water when chemically breaking down (oxidising) all the organic and inorganic present. Results are given as mgO2/l.

The closer together the BOD and COD figures are, the greater the biodegradability of a product. When selecting a product, you should always look for one that has a low BOD/COD, i.e. is readily biodegradable in the environment.

C6 is the name of the fire fighting foam reformulation project that was initiated in 2013 because of the EPA 2010/2015 PFOA Stewardship Programme.

It is called C6 as only fluorosurfactants with an (R_f) chain length of C6 were allowed to be used in fire fighting foams from 2015.

Further information can be found here.

All traditional Fire Fighting Foams contain fluorosurfactants. Fluorosurfactants aid fire extinguishment and support excellent burnback properties.

 However, a USA EPA working group has found that fluorosurfactants containing R_f carbon chain length greater than C6 could potentially degrade in the environment and form PFOA, a chemical which is bioaccumulative, toxic and persistent.

 Due to this discovery, in 2005 the EPA convened what has come to be known as the 2010/15 PFOA Stewardship Programme. Under this programme, all fluorosurfactant manufacturers worldwide (except those in China) have committed to withdraw from sale any fluorosurfactant with a carbon chain length greater than C6 by 2015.

For further information, please see our EPA 2010/2015 PFOA Stewardship Programme page.

PFOS (perfluorooctane sulphonate) is a chemical which used to be commonly used in fire fighting foam, as well as a preservative in clothing and in other industries and applications. 

As far as we know, PFOS does not degrade in the environment and will remain in the environment for a very long time. The chemical can accumulate in the body, primarily in the liver and gallbladder. Studies of different animal species show that the substances accumulate in the food chain. The results of EPA research estimate that 98% of the U.S. population has accumulation of PFOS in their body. 

PFOS is toxic with repeated exposure and has been shown to have adverse reproductive effects in mammals. There are also studies showing that the chemical may be carcinogenic. PFOS is toxic to aquatic organisms and may cause long-term adverse effects in the aquatic environment.

The use of PFOS in many countries has been either virtually banned or banned completely due to its known environmentally hazardous properties.

Further information can be found on the Environment Agency website.

Perfluorooctanoic acid (PFOA) is a long-chain perfluorinated chemical (LCPFC) that does not occur naturally in the environment. LCPFCs are synthetic chemical substances with special properties and hundreds of manufacturing and industrial applications. 

PFOA is of concern as:

•  It is very persistent in the environment
•  It is found at very low levels both in the environment and in the blood of the general U.S. population
•  It remains in people for a very long time
•  It causes developmental and other adverse effects in laboratory animals