The pH is tested on every fire-fighting foam concentrate sample sent to Dyne Technologies.  The pH can help indicate the condition of the foam concentrate.  For samples tested to NFPA 11, pH is not a measurement of performance and will not cause a sample to fail.  However, a concentrate being tested to International Maritime Organization (IMO) Specification MSC 1312 and NFPA 18 Standard on Wetting Agents requires foam concentrate to have a pH within a set range to be acceptable.

What is pH?

In chemistry, pH is the measure of the hydrogen ion concentration of a solution, in other words, it is a way to measure the acidity or basicity of a solution.  The pH scale is a logarithmic scale, ranging from 0 - 14.  The pH of a neutral solution is 7.0 at 25 degrees C.  An acidic solution has a pH less than 7.0, while a basic solution has a pH more than 7.0.  For example, lemon juice, which is an acid, has a pH of 2.0, and Household bleach, which is a base, has a pH of 13.0.

What does an “Out of Spec” or “Fail” pH mean on a Dyne Test Report?

pH will not cause an NFPA 11 sample to fail, however if the pH of the sample is outside the pH range of 6.0 - 9.5, the result will appear as “out of spec”. Investigation is recommended if the pH is outside the 6.0 - 9.5 range.  A pH less than 6.0 means that the sample is fairly acidic, while a pH greater than 9.5 means the sample is fairly basic.  A pH outside of 6.0 - 9.5 can indicate corrosion or contamination within the tank.  An acidic or basic foam solution can also be a sign of degradation of the foam concentrate, which may be caused by:

  • Dilution
  • Evaporation
  • Unsuitable storage conditions
  • Unsuitable storage temperature
  • Aging

The International Maritime Organization Specification MSC 1312 and NFPA 18 (Standard on Wetting Agents) requires foam concentrate to have a pH between 6.0 and 9.5, and 6.0 to 9.0, respectively. If a foam sample is being tested to one of these specifications, and has a pH outside of this range, the sample will FAIL regardless of the other test results.

For an explanation on all physical properties and performance properties tested on firefighting foam samples, refer to Foam Testing Explanation LBTR-4054 on the Dyne Technologies website.  If you have any questions, our chemists are always available to answer them.  Call Dyne at (800) 632-2304 or email,, for assistance with understanding your test results.

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