During the market transition from AFFF (Aqueous Film Forming Foam) to SFFF (Synthetic Fluorine-Free Foam) concentrates, it is important to know the viscosity of the SFFF concentrate to choose the right type of proportioner, said Firemiks for an exclusive article in International Fire and Safety Journal (IFSJ).
FIREMIKS, a water-driven volumetric pump proportioner, is used for firefighting in fixed installations connected to a concentrate tank.
The system operates by using extinguishing water to drive the volumetric water motor, which in turn drives the positive displacement pump to dose the correct amount of concentrate into the water.
Regulatory authorities are pushing for a swift transition from PFAS-containing concentrates to SFFF concentrates.
Different concentrate manufacturers offer a variety of foams with a wide range of viscosities, including very high viscous concentrates.
It is essential to select an appropriate proportioner based on the properties of the concentrate.
Water motor-driven pump proportioners equipped with gear pumps are particularly suited for operating in the higher range of a system’s maximum flow rate, such as deluge and large fire monitor systems.
These are most suitable for high and very high viscosity concentrates.
FIREMIKS has successfully tested a gear pump model with a fluorine-free foam with 8,040 cP.
Gear pumps work well with very high viscous concentrates due to their counter-rotating gears, which seal better with high viscosity fluids and create an even flow that does not agitate the concentrate.
Water motor-driven pump proportioners equipped with piston (plunger) pumps are particularly suited for use in systems with low start-up flows in relation to the system’s maximum flow rate, such as sprinkler systems.
These are well-suited for low and medium viscosity concentrates.
Piston pumps are generally limited to high viscosity concentrates around 4,000-4,500 cP.
The reciprocating principle of piston pumps, where the plunger sucks and presses out the concentrate, may not work well with non-Newtonian concentrates if the static viscosity is too high.
This can affect the correct dosing rate.
To measure and verify the dosing rate on a proportioning system according to regulations and standards during commissioning and yearly maintenance is important.
The aim is to ensure that the firefighting system proportions the correct amount of concentrate into the water flow as intended.
FIREMIKS units can be equipped with an optional dosing return valve that directs the concentrate back to the tank for testing without mixing the concentrate.
This setup includes a pressure relief valve to prevent over-pressure and two calibrated flow meters to measure the main water line and the concentrate return line.
The flow meters, valves, and pressure gauges can be handled on site or connected for remote monitoring.
The key is to ensure accurate data measurement according to standards to guarantee the correct proportioning of concentrate into the firefighting water flow.
