 Wildland
Fire Chemicals
Evaluation of Wildland Fire Chemicals
Standard Test Procedures (revised 5/16/06)
STP 9.4—Effect of UV Radiation on Enhanced Water Mixtures
Summary:
The susceptibility of water enhancers to degradation by sunlight and/or
ultraviolet radiation may be assessed by exposure of the mixed product
for a specific amount of time under a standard light array.
A solar simulator is used as the standard light array. It is equipped
with a combination of cool white, UVB fluorescent lamps, UVA fluorescent
lamps, and halogen flood lamps. This combination results in light similar
to that outdoors having a nominal irradiance, in µW/cm2 of
3941 in the visible range, 2385 in the UVA range, and 241 in the UVB range.
Equipment:
- Solar simulator Brookfield LVF viscometer, set to a rotational
speed of 60 rpm
- Spindle set with spindle numbers 2, 3, and 4
- Exposure container—shallow, glass container such as a baking
dish
Test Method:
- Prepare approximately 1 liter of the enhanced water mixture using
deionized water. Use the previously determined mix method for the
specific product.
- Measure the viscosity of the mixed product at 10 minutes and 60 minutes
after mixing. Record the dial reading, the spindle used, and the rotational
speed, used to obtain each reading.
- Place 500 mL of mixed product in a clean glass jar, cap tightly. This
jar shall be kept in the lab away from direct sunlight to act as a control.
- Place two samples in exposure containers to a depth of ¼ inch.
- Place the exposure containers under the solar simulator.
- After 4-hours exposure, remove one sample from the solar simulator.
- Measure the Brookfield viscosities of the control and 4-hour exposure
sample. Record the dial reading, the spindle used, and the rotational
speed used to obtain each reading.
- After 8-hours exposure, remove the second sample from the solar simulator.
- Measure the Brookfield viscosities of the control and 8-hour exposure
sample. Record the dial reading, the spindle used, and the rotational
speed used to obtain each reading.
- Determine the change in viscosity of the product exposed to solar
simulator and of the product kept in the lab.
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