Low-expansion foam generators operate with a pre–mix feed. The foam nozzle converts the supply pressure into speed with the air suction function, which vigorously agitates to produce the foam sprayed from a distance.
Low-expansion foam generators
The foam nozzles are available in two versions, a self-suction version of the emulsifier, which involves transporting the emulsifier can with the nozzle, and the non-self-suction version where the premixing is carried out using a proportioner generally installed near the emulsifier supply.
These two options each have their advantages and disadvantages. For the non-self-priming version, the passage through the proportioner reduces the pressure by at least 35% and even 40% if the injector does not have an auto-regulating system. This reduced pressure limits the flow rate available for the nozzle. As for the auto-suction system, it requires to transport the emulsifier close to the foam nozzle and replace it regularly.
Non-auto-suction foam lance
Non-auto-suction foam lance uses the principle of a resonance chamber between two diaphragms
Non-auto-suction foam lance uses the principle of a resonance chamber between two diaphragms whose turbulences stirred the air at the outlet, generating beautiful foam. For the self-suction system, the system operates with a convergent to provide a velocity of the jet, looking like the pipe of an organ. The output proven by this device was highly efficient.
At the end of the 1980s, POK S.A.S had no test facilities and experts at the organization were required to go to industrial areas and use pressure and flow from the hydrants to improve the characteristics of the appliances.
New Nogent-sur-Seine facility site
Later on, when POK moved to their Nogent-sur-Seine site in France, they were able to implement more serious test methods with which the devices were able to refine their characteristics, allowing continued surpassing of the copies of their devices by Asian manufacturers.
It should be noted that in some regions, even in Europe, the emulsifiers used for testing do not comply with European standards, therefore the test results may have differed from those announced in the product specifications. POK’s expertise in this field allows for adjusting the results according to the qualities of the emulsifiers, knowing that any change has a cost.