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Name: John G. L.
Status: Educator
Age: 40s
Location: N/A
Country: N/A
Date: August 2004


Question:
With respect to the surface tension of water and droplet size when a surfactant is added to water to create a wet water solution. If we take water with a surface tension of approximately 73 dynes and add a fire fighting foam surfactant to the water thus reducing the surface tension to approximately 24 dynes (approximately 1/3 of the original surface tension of the water)- What would the droplet size of the solution be in comparison to the size of original water droplet?



Replies:
What water droplets? Eyedropper (slow), atomizer (small), fire extinguisher nozzle (fast), fire-hose (massive)? Depends on your spraying apparatus. It may not vary too much or too consistently with surface tension. Foamy compound implies added viscosity, too. Which is just as likely to influence droplet size.

Making droplets from an atomizer or hose-nozzle is a dynamic sort of thing. Time and momentum and aperture size and turbulence. Especially aperture size. It feels plausible that an intellectually tidy dependency on surface tension could be arranged intentionally, but I cannot think of that scheme offhand.

Jim Swenson



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