W + Conc +A + A = Foam (Foam is Bubbles and Bubbles is Water)
Batch mixing is a simple method for making Solution (W + Conc) without a machine, but as you read on, you’ll find there are considerations.
Batch mixing – The simplest method to make Solution (W + Conc). Just pour the Concentrate in the Water Tank. But Wait!!!!
First, Calculate the number of gallons of water in the tank and multiply that amount by .5% (for making NAF) or .3% (for making CAF) to determine the amount of Concentrate to pour in the water – Yes, the tank.
After adding the Concentrate to the Water, recirculate the water for for a few minutes to insure that the Concentrate blends into the water. You now have Solution in the tank.
The next step is to add the Air and Agitation to make Foam.
Batch mixing can be an extremely accurate method of making the correct % Solution if the firefighter’s math and measuring skills are right on and the measuring can keep up with the changes in the Water tank levels during a prolonged incident. But, since this can very easily be impractical, there are concentrate systems that can keep up automatically and can mix the Solution accurately as needed with no wasted Solution left over in the tank.
Some considerations to Batch Mixing:
Solution Degradation (Similar to Dish Detergent degradation in the sink)
Solution not used
Cleans Grease from pump bearings, seals
Constant Calculating the amount of water added to the tank to the new amount of Concentrate to add to keep the correct % Solution.
For other methods of adding Concentrate to Water — see Concentrate Systems.
