Why foam concentrate needs a positive displacement pump
Foam concentrate is viscous, and some types thicken further as the temperature drops. It has to be injected into pressurised water, so the pump must push against that pressure and keep its flow rate. A gear pump moves a fixed volume at every revolution whatever the back pressure, which is why it is the usual choice for foam proportioning.
The pump should also move the concentrate gently. Gears turning at moderate speed transfer the liquid without whipping air into it, so it foams where it should: at the nozzle.
Proportioning: flow that follows speed
Foam concentrate is dosed in proportion to the water flow. Since the delivery of a gear pump is proportional to its speed, you adjust the dose by adjusting the revolutions.
The series we normally propose: NAV and ZV
For foam concentrate we normally propose the flanged NAV series for large fixed systems and the ZV series for small flow rates and compact skids. The model, the materials and the speed must be confirmed by our technical office for your concentrate. Bodies are available in cast iron or AISI 316 stainless steel.
Marine and fixed fire protection systems
The marine sector uses our pumps for foam concentrates as well as for fuel oil and diesel. On land they serve fixed systems in depots and process plants, often next to pumps for thermal oil.
A fire pump stands still for long periods and must start at once. Self-priming helps here, because the pump draws the concentrate from the storage tank unaided. We supply the bare shaft pump or the complete unit on a baseplate, built and tested in Bologna, Italy.
