Is anyone out there running automatic nozzles for lines are meant to be used with inline foam eductors that require the nozzle GPM and eductor GPM to match? Reason I ask is that it is a growing trend around these parts that departments spec all automatic nozzles on new engines. When training, the 95 GPM foam eductors that also came with the trucks don't work well with the automatic nozzles (which should be expected but for some reason is overlooked at spec time). So, being as the trucks have what they have on them, are any of you in the same boat but somehow making good foam with you automatic nozzles?
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07-12-2011, 04:24 PM #1
Foam Operations with Automatic Nozzles
07-12-2011, 04:47 PM #2
- Join Date
- Aug 2009
Automatic Nozzles and Foam
Mt department went through this about 10 years ago. We used TFT and Elkhart automatics. We have since changed to Akron mid-range Turbojets, along with 125 GPM Akron eductors.
We found poor blanket production with automatics unless the optional aerator was used. TFT had one that fit their nozzles and it produced a nice thick blanket. However, we could never be sure of the GPM.
Even with our current Akrons, we used flowmeters to verify GPM and proper foam percentage. At less than recommended PDP we found that we could develop a good blanket but the GPM was lower than we though (125) but we were getting almost 10% foam (when using an eductor set at 3%). At the proper PDP (200 PSI with 150' of hose) we got the proper GPM and the foam concentration fell into line. Somewhere we developed the (incorrect) notion that if you had enough PDP to draw foam into the line, then that's all the PSI you need.
Follow the manufacturer's recommendation for PSI. I would imagine the the automatic nozzle makers have their foam application procedures on-line, although it may require an aerator to make the best finished foam.
07-13-2011, 05:20 PM #3
- Join Date
- Jul 1999
- Rural Wisconsin, Retired from the burbs of Milwaukee
16Scott is exactly correct.
If you use an inline eductor, and pump that eductor to the right pressure (usually 200 psi at the inlet of the eductor), AND the automatic nozzle has the capability to flow the same gpm as the eductor, it will work perfectly.
How do I know? Back in the dark ages when my POC FD used TFTs we did just as I said above and it worked just fine. When we moved away from TFTs we pulled an old Turbojet from the shelf, put an aeration tube on it, left it set at 125 and BINGO! it worked fine to.Crazy, but that's how it goes
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