Positive displacement foam pumps have been a critical piece of firefighting foam systems for a very long time. It’s the only type of pump you should use to pump foam concentrate to Balanced Pressure (BP) proportioners or remotely located In-Line Balanced Pressure (ILBP) Proportioners. UL listings and FM approvals for these pumps is critical to ensure the reliability and performance criteria are going to be met.
With the recent industry changes with firefighting foam moving to Synthetic Fluorine-Free Foam (SFFF) or PFAS free foams, pumps most likely will require to be retrofitted to maintain the system performance.
The older pumps of yesterday may not be suitable for the new systems and foams of today.
Aaron Johnson
Each system needs to be reviewed on a project-by-project basis.
By far, the most common challenge we see today, and help customers with, is the accurate calculation of system demand and system supply when using SFFF. A major challenge is that pseudoplastic fluids, like firefighting foam, do not follow Newton’s law of viscosity, meaning their viscosity decreases as shear rate increases. This directly impacts friction loss calculations, making traditional methods like Hazen-Williams unsuitable.
Instead, viscosity effects must be properly accounted for—not only on the system side of the pump to the foam injection point but also on the suction side of the pump when determining Net Positive Suction Head Available (NPSHa). Per NFPA 20, NPSHa must be at least 5 feet higher than NPSHr (Net Positive Suction Head Required) to prevent cavitation.
Given the complexity of these calculations with thixotropic and pseudoplastic fluids, Fire Lion has the expertise to assist customers in ensuring proper suction piping size and design, safeguarding system performance when switching foam agents. Every system design and retrofit must be evaluated to account for these critical factors.
Fire Lion can provide a “Turnkey” solution for end users ensuring that the pump performance is adequate for their critical life safety and infrastructure protection system.
Our sales, engineering and production staff can provide very detailed and complete solutions for their listed and approved foam pump systems.
Aaron Johnson
From NPSHa calculations to fully engineered foam pump skids, to Electronic Foam Proportioners (can test the system without discharging water or foam), to full commissioning and start-up services, we are the only one stop shop for your foam pump needs in the industry.
With today’s retrofits to SFFF type fluids, the NPSHa is critical as the new fluids will most likely require larger suction piping and/or modification to the suction piping design.
The second concern is the friction losses downstream of the pump to the ILBP proportioner. The friction losses will increase with the system modification to SFFF so the piping design and sizes downstream of the pump can also be affected. A full design review must be conducted to verify what will be required.
