Water Handling Equipment Guide - National Wildfire Coordinating ...

FOAM GENERATING EQUIPMENT
Foam Proportioners
Table 3—Advantages and disadvantages of proportioning devices.
Proportioners*
Advantages Manually Automatic
regulated
regulating
1 2 3 4 5 6 7a 7b 8 9
Maintain desired mix ratio with changes in waterflow & pressure X X X X X
Unlimited hose length X X X X X X X X
Unlimited number of hose lines X X X X X X X X
Easily adjusted mix ratios X X X X X X X X
No moving parts X X X X X X
No loss in water pressure X X X X X
No loss or low loss in water pressure X X X X X X X X
Operate from pressure source X X X X X X X X X
Requires no equipment investment
X
Refill foam while operating X X X X X X X X
Can indicate foam concentrate remaining X X X X X X X X X
No external power required X X X X X X X
Disadvantages
Tank and pump corrosion X X X
Plumbing corrosion X X X
Pump cavitation X X X
Possible pump priming difficulties X X X
Foaming in tank X X X
Water tank refill fluid level obscured X X X
Clean water supply contamination X X X
Removes lubricants from pump X X X
Possible use of more concentrate than required X X X X X
Possible use of less concentrate than required X X X X X
Possible inconsistent dispersion of concentrate X X X X X
Foam solution degradation
X
Cleaning required after every use X X X X X
Specific waterflow requirements
X
Specific pressure requirements X X
Limited nozzle elevation X X
Must match hose length and nozzle X X
Limited hose length and size X X
High discharge pressure loss X X
Cannot operate from water pressure source
X
Dependent on pump vacuum
X
Concentrate viscosity affected X X X X X X
Concentrate resupply interrupts concentrate input
X
Requires auxiliary power X X X
Accurate Water Flow Range
Any flow, single mix ratio X X
Single flow, single mix ratio without adjustment X X X X X
Any flow, any mix ratio (between 0.1 and 1.0 percent for class A foam) X X X
Initial Equipment Investment
$ 0 - $ 500 X X X X X
$ 500 - $1,000
$1,000 - $2,000 X
$2,000 - $4,000 X X X
$4,000 - $6,000
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X