by Evelyn Vogel
What is the difference between foam concentrate and foam solution or shell water and system water? To receive the most accurate and timely testing results, Dyne must know what type of foam or water is inside each sample bottle. Figure 1 shows part of the Dyne Foam and Antifreeze form. For easier use, this part of the form was recently reformatted. The concentrations are now split into non-alcohol resistant foam options and alcohol resistant (AR) foam options.
Figure 1: Part of Dyne’s Foam and Antifreeze sample form.
Foam concentrate is pure foam that has not been mixed with water. Most drums, pails, and tanks contain foam concentrate. There are some foams that come already premixed with water in the containers; however, they are less common. Foam concentrates tend to be more vibrant in color than foam solutions. Often, they are yellow, amber, gray, brown, green, and blue, although there are colorless foam concentrates. Another potential indicator specifically for alcohol resistant foam concentrates is viscosity. Most alcohol resistant foam concentrates are thicker than water. They may look like syrup or honey. If a sample is a foam concentrate, the “Foam Concentrate1” box should be checked on the form. These samples will be tested for their physical properties and their performance.
Once the foam concentrate is mixed with water, often times using a proportioner, it becomes a foam solution. Foam solutions are usually colorless or they may have a slight color to them. The exception to this is protein foam solutions, which tend to be brown. Foam solutions are mostly water (94% to 99% water) so they are not viscous. Foam solutions can be tested for their performance (NFPA 10 2018 Ed. Section 22.214.171.124.3) and/or their percent concentration (NFPA 11 2016 Ed. Section 11.6.4). The Solution “Performance2” and/or “% Concentration3” boxes should be checked for these samples, respectively. Foam solutions from a proportioner can degrade over time. The performance may diminish but the concentration will stay the same. Because of this, it is suggested to test the performance only for samples that were purchased as a premixed solution and test the percent concentration for samples that come from a proportioner.
The water that is combined with foam concentrate to make foam solution is system water (also called fire water). System water may be drawn from the tap or a nearby water source. This water can be different from state to state and even city to city. As a result, Dyne strongly suggests that a sample of system water per proportioner is sent in for percent concentration testing. The water is used to make up standards against which the foam solution sample is compared. Using Dyne tap water may give different results. To indicate system water that is to be used for foam solution percent concentration determination, check the water “System5” box.
Shell water (also called bladder water) is water that is inside a bladder tank, as seen in Figure 2. When foam gets warm, it expands. The water acts as a flexible barrier and helps protect the bladder from rupturing. Tears may occur in the bladder bag. If there is a tear, foam concentrate will leak into the bladder water. Testing the shell water may help indicate if there is a tear in the bladder bag.
Figure 2: A foam bladder tank. Image modified from www.weiku.com under foam bladder tank.
A foam solution will fail the foam concentrate tests and vice versa. Therefore, it is imperative that the paperwork is filled out properly. There may be delays in testing or additional costs if the samples are not marked correctly on the paperwork. If ever you have questions on how to fill out the paperwork or what kind of sample you have, call Dyne and the staff can walk you through the process. Should you need any more information regarding this topic, please contact Dyne Fire Protection Labs at (800)632-2304 or firstname.lastname@example.org.