Why mixing foam at the right proportioning rate (%) is crucial for extinguishing fires
- Extinguishing foam
- Foam concentrate
- foam equipment
- Foam proportioner
- Sharing knowlegde
One of the standards that lists foam concentrates and equipment is FM. Foam agents could be listed in combination with a specific piece of equipment, but having a FM approval does not necessarily mean that particular piece of equipment works with any type of foam agent, or the other way around.
NFPA tolerances on the proportioning of a 3% foam concentrate = 0 percent to 30 percent (3,0% to 3,9%). You can run a test and pass with 3,3% (temperature was 15°C). Next time, you run another system test and this time it is 5°C. Possibly you end up at 2.5% or lower proportioning rate. Selecting a proportioning device that works over a wide range of foam viscosity is therefore of importance.
A thicker foam agent will most likely flow through equipment much slower and require a higher flow to move faster, meaning that current installed foam pumps and proportioning devices will need to be carefully looked at when switching to alternative foam agents that have a different type of viscosity and could be influenced by temperature changes.
A gear pump can handle fluids that are too viscous for a centrifugal or piston pump. The pumping action of a gear pump is very controllable and mathematical: The output of a gear foam pump is independent of discharge pressure.
Since a gear pump doesn’t have to generate centrifugal force, it can be run at a much lower speed. This makes it smoother, more precise, quiet and controllable.
Gear pumps are self-priming, which can be a huge benefit as that they poses a huge fluid suction lift. Their discharge pressure can be very high, dependent upon a number of factors. A gear foam pump dos not have a BEP or best efficiency point; they are consistently efficient.
Positive Displacement Pump
The positive displacement pump provides and constant flow depending on demand at affixed speed, despite changes in the counter pressure.
By using an gear Pump combined with a positive displacement Pump, Knowsley has developed the Turbinator, an innovative water Driven Foam portioner that provides simplicity housed in one single body.
The Turbinator is a positive displacement foam proportioning pump designed for Fixed and Mobile applications. The unit is driven by a special volumetric water motor which is directly coupled to a precision gear foam pump. Because both parts of the Turbinator are positive displacement devices, the ratio of foam concentrate to ﬁrewater is ﬁxed over the full operating range. This makes the Turbinator the ideal proportioning technology for systems with different ﬂows, such as multi-legged deluge systems, sprinkler systems and mobile large incident equipment.
The Turbinator unit does not require setting up or on-site adjustment – the proportioning rate is achieved at any ﬂow rate and pressure within the operating range.
Design and installation: simple as 1-2-3
The close-coupled design offers a very compact and efﬁcient installation with just three connections: ﬁre water inlet (1), foam concentrate inlet (2) and foam solution outlet (3). The unit can be installed directly into vertical or horizontal piping systems. The Turbinator foam pump delivers 3m suction height easily, which makes it possible to install the foam concentrate tank below the unit installation level – even with high viscosity concentrates in arctic conditions (thick foams). Simple, cost effective atmospheric foam tanks are ﬁne for Turbinator.
With its unique low differential pressure, Turbinator ﬁts in the most complicated systems, even when long pipe runs or static pressure loss are involved. Turbinator does not require external power supply or control circuits and is safe for any ATEX environment. The Turbinator is available in 3 sizes from 500 l/min to 12’000 l/min with proportioning of 1% and 3% with freshwater and saltwater construction.