 Wildland
Fire Chemicals
Evaluation of Wildland Fire Chemicals
Standard Test Procedures (revised 5/5/06)
STP 8.3—Foaming Ability
Summary:
This procedure is used to determine the ability of foam solutions to
foam and how quickly the foam drains from the bubble structure.
The concentration
of the foam solution, the temperature of the solution, and the quality
of the water used to prepare the solution—distilled, tap, or sea—will
affect the foaming ability of the solution.
Equipment:
- 100-mL graduated cylinder with a glass-stoppered top. The graduated cylinder
should have volume markings below 5 mL for most accurate measurements.
- Foam
solution
- 10-mL pipet or syringe
- Countdown timer
Method:
- Prepare a solution of the test product, using the required concentration,
water temperature, and water quality.
- Record the details of the
test solution.
- Add 10 mL of the freshly prepared foam solution
to the graduated
cylinder, using the pipet or syringe.
- Insert the glass stopper
into the cylinder.
- Agitate the solution by shaking the
cylinder vertically,
as vigorously as possible, for 10 seconds, while holding
the stopper down with one finger.
- As soon as shaking is
finished, start
the timer and immediately note the total volume of
foam in
the cylinder.
- If
the level is uneven, estimate the average volume.
- Measure
the volume of liquid in the bottom of the cylinder at the end
of 1, 2, 3, 4, 5,
10 and 15 minutes.
- Record the elapsed time and
volume on the data sheet.
- Calculate the foam expansion
using the
formula below:
Foam Expansion = Volume of Foam/Volume of Solution
- Determine the foam drain rates by plotting the volume of solution
drained from the foam against the time in minutes. A 25-percent
drain time is the time required for 2.5 mL of solution to drain
from the foam that was produced from 10 mL of solution.
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