There are a number of implementations of balanced proportioning systems. These systems use a venturi device that is a variant of the line proportioner. The venturi produces only a moderate low-pressure zone and the pressure reduction in the proportioner is proportional to the flow through the proportioner. If the foam concentrate is supplied to the proportioner at the same pressure as the water then the proportioning rate is constant over a wide range of flows. Turn down ratios of 7 to 10 are possible with these systems. Bladder tank systems use the water from the water supply to pressurise a bladder containing foam concentrate. The bladder tank system naturally balances the water and foam concentrate pressures. This method is relatively low cost but refilling the system is quite difficult making them effectively one shot systems in an emergency.
Standard proportioners are manufactured from gunmetal, alloy C83600 per AS 1565. We can also manufacture our proportioners from Aluminium Bronze for harsh
Pressure loss through the proportioners is 100 kPa at maximum flow.
Models are fitted with a diffuser for optimum performance.