A Few Things to Consider when Sampling Foam
Ensuring a representative sample of the firefighting foam that is taken and sent to Dyne is essential in ensuring safety, receiving a quick and accurate result turnaround, and to limit future retesting expenses.
COLLECTING A SAMPLE THROUGH A PIPE
Whenever a sample is collected off of piping, be sure to run some foam through the lines before sampling. These pipes can contain contamination as well as corrosion which will negatively affect the performance. Any corrosion left in the sample from metal piping can also lower the pH of the foam. By running some foam through the lines, this allows that contamination to be cleared out and for a clean, representative sample of the foam to be collected. Sediment found in foam can also affect foam equipment as well as the foam performance itself. For this reason, some specifications do require that a foam contain less than a specified percent of sediment. An improper sample being taken resulting from the failure to clean the lines before collecting can lead to some costly false conclusions about the integrity of the foam.
BLADDER TANK SAMPLING
Note that a bladder tank typically contains both a foam concentrate on the inside of the bladder and water between the bladder and the tank. According to NFPA, the bladder water should be sampled and analyzed to help in determining a possible bladder rip. If the sample being taken is a foam concentrate sample, keep in mind that these tanks contain a large volume of foam that may not be uniform throughout. The tank should be sampled from two different areas, the top and the bottom for example, to help ensure that the foam is acceptable throughout. There can be water and other contaminants in the foam concentrate from a variety of sources such as a leaking bladder tank, a poor design, or an inadequate or missing isolation valve. Since foam concentrates generally have a density greater than water, water or other contaminants may be more likely found in a sample taken from the top of the tank. In this situation, taking just a top sample may result in the lab determining that the sample taken isn't meeting the manufactures specifications. It will, however, help you possibly identify issues. Taking a bottom sample in this case may show that some of the foam is still within specifications and may perform adequately allowing for a portion of the foam to be salvaged. However, consider that in some thicker foam concentrates, water and other contaminants may not rise to the top as easily due to the viscous nature of the concentrate. These contaminants can become trapped at different areas of the foam under the right conditions. For these reasons, to ensure a bladder tank does indeed contain good foam throughout, it is recommended to take samples from two different areas of the tank.
SAMPLING FOAM WITH MINERAL OIL
A special circumstance to consider with some foam concentrates is that a few have mineral oil placed on top of the foam by the manufacturer to prevent evaporation. This mineral oil, unfortunately, can affect the performance of the foam. When taking a sample from the top of a container or tank, pay careful attention to the appearance of the foam. If a clear, slimy liquid is found separated from the foam and sitting on top, you may have sampled a percentage of mineral oil. It is suggested that you make sure any samples taken in this situation be sampled from the foam below the mineral oil layer. There are various pumps that are sold that can assist you in this case if needed. However, keep in mind that with thicker foam concentrates, contaminants can become trapped. That means that if a tank was topped off with foam that already had mineral oil placed on top, this mineral oil can now be trapped in the foam. Sampling from more than one area of the tank can help determine if this situation has happened.
SAMPLING FOAM FROM A RELATIVELY SMALL CONTAINER
When taking a sample from a container of relatively small size, use the appearance of the sample to your benefit. Vast color differences between two areas of the foam will indicate that the foam is not uniform throughout. Any contamination may also be seen in only parts of the foam. Use your best judgment to determine if the sample you have taken is representative of the whole tank or just a small percentage of the tank. Make sure in this situation to collect a composite sample or several different samples to represent the whole tank.
PROPERLY FILLING OUT THE PAPERWORK
Filling out the paperwork completely and correctly is essential in ensuring safety, receiving a quick result turnaround, and limiting future retesting expenses. When filling out the paperwork for a foam sample, make sure to fill out all the required entries which are conveniently highlighted in red on our foam sampling form. Each entry is important for the testing of the sample. Note that the entry for nominal concentration is asking for what percent the foam is used at. This should match the percentage(s) listed for the foam when purchased and what the foam equipment is portioning at. Also note that any information given on the form will be included with the report and tank tags (tank tags only given for passing results). This information can be helpful in the lab's analysis and can make future testing more efficient. Any missing required information may delay the results. Feel free to call Dyne at (800) 632-2304 or email firstname.lastname@example.org with any questions when filling out the paperwork. If you have further issues or questions when sampling, please feel free to contact Dyne for assistance. We are always available to help and look forward to assisting you with your compliance testing needs.