Dyne Technologies performs various physical property tests in order to better understand a firefighting foam sample. An important physical property that can tell us a lot about a sample is the appearance, which is the description of the color, consistency and the visible presence of sediment and particles.
An “out of spec” color on a Dyne foam report means that the firefighting foam sample appears different than when it was newly manufactured. Normal aging of the foam can cause a slight color change. An “out of spec” color may also indicate that the sample is really a different product than what was specified on the foam sampling form. Different products may have different test specifications, and an incorrect product may give the wrong conclusion about the quality of the foam. Another possibility is that concentrate in the tank has been topped with a different colored product at some point. Take care when topping off tanks as not all foam concentrates are compatible with each other which could also lead to chemical reactions changing the color of the concentrate. Lastly, rust coloring can indicate interaction (corrosion) of the tank or piping with the foam concentrate. It is important to note that the performance properties of a sample with rust may be deteriorated. When sampling firefighting foam, make sure to not obtain a sample that has been sitting in the system piping, as it is not a good representation of the entire tank.
In addition to color, appearance may be “out of spec” when the sample has abnormalities such as a polymer chunk(s), layer of mineral oil, sediment, or particulates. Polymer chunks may indicate the polymer is dropping out of the solution. Evidence of this may also be seen in an “out of spec” or “failing” viscosity result on an alcohol resistant aqueous firefighting foam (AR-AFFF). This can be caused by a number of reasons such as improper mixing of foams or extreme storage conditions. Not only will this diminish the firefighting capabilities of the foam, the separated polymer can plug the proportioning orifice and prevent the foam concentrate from mixing with the water supply correctly.
Mineral oil is sometimes added to the top of foam concentrates to prevent evaporation of the solvent. The mineral oil can become engrained in the foam if the tank is topped off or agitated which can cause the sample to perform poorly. Dyne offers a supplemental test as a way to confirm if a sample has mineral oil with the Mineral Oil Determination Test. If mineral oil is found, resampling below the mineral oil layer could produce more representative results.
Sediment or particulates are often the result of equipment corrosion that the foam has come into contact with during the sampling procedure. An excessive amount of sedimentation can affect performance or even clog the proportioner. Dyne offers a supplementary Percent Sedimentation Test in which samples are centrifuged so the solid material can be measured and a percent sedimentation can be calculated. The Percent Sedimentation Test is done on all International Maritime Organization (IMO) samples as required, but the test can be requested on any National Fire Protection Association (NFPA) sample.
For an explanation on all physical properties and performance properties tested on firefighting foam samples, refer to Foam Testing Explanation LBTR-4054. If you have any questions about appearance, polymer separation, sediment, mineral oil, or any other test, our staff chemists are ready to answer questions. Call Dyne at (800) 632-2304 or email, firstname.lastname@example.org, for assistance with understanding your test results.