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Back to Basics Part 4: Foam Eductors
This is a foam eductor. Remember these things?
Hey, do you remember these? You know, before we had foam tanks on all of our trucks?
Before we could pump foam out of every discharge?
This is an old fashioned foam eductor and a bucket of foam.
When is the last time you had one of these in your hands? How about the last time you actually flowed one? Well, unless you just completed a foam class or a Firefighter 1 & 2 class, it has probably been a while.
Don’t forget about this appliance. On a large spill or fire, these are actually easier to use than the tank foam because you can just dip the eductor into the bucket and keep changing out buckets where as you have to haul those 5 gallon buckets and dump them into the tank otherwise. That is a pain in the a@#!
Anyway, they are a useful but forgotten tool on our trucks. Get familiar or re-familiar with them. There are some rules that apply when using them though.
Okay, homework, what are some conditions, requirements or limitations for the use of these eductors? I don’t have any prize, but, this is a great training discussion. Officers, make sure your engineers know how to use these.
Good luck and report back with your answers soon.
Replies to This Discussion
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Permalink Reply by John Crabbe on
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On a large spill or fire, these are actually easier to use than the tank foam because you can just dip the eductor into the bucket and keep changing out buckets
I would hope there is one on each pump still out there because for most cases the foam on most engines with pre piped foam tends to be class "A" foam vs class "B" where you may see these in operation. Then there is also alcohol resistant foam, so basically too many instances where a pre piped foam system on a rig makes it impractical for use in every situation and ths the importance of this tool.
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Permalink Reply by Mike Schlags (Captain Busy) Retd on
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Don't ever draw your tank water down to where you loose your prime... We tried using a large eductor in a stream bed using an oversized aluminum scoop shovel to prevent sucking up rocks from the bottom of the stream bed. Everything was working just great until we opened up the Master Stream Stang on top of the engine. It overpowered what the eductor was able to provide which rule of thumb is 1.5 gallons discharged for every 1 gallon pumped to the eductor. Had we not opened up the stang, water filling ops for a tender for example could be done very easily. These larger water eductors are used routinely to de-water large ships when copious quantities of firefighting water pose the risk of capsizing a vessel. The use of eductors is really important in situations such as earthquakes where water lines are damaged or wildland fires where the supply has been drawn past what it can provide through the municipal system.
CBz
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Permalink Reply by Luke Summers on
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HaHa foam eductors are all we have. Also make sure you clean them out real good after every use or you will have fun trying to deploy them in the future.
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Permalink Reply by Shaun Hansen on
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We just got an in-line eductor and asperator nozzle. We currently have a on board foam system on our engine, but it is always filled with Class A foam. We bought the in-line system for flowing our ARFFF foam. We accually train with these at least twice a year. They do serve a great purpose and should not be thrown in the corner. Some of the limitation of this system would be that they have to be connected directly to the truck discharge. You have to run the pressure to the nozzle higher then normal to creat a strong enough ventury to syphon the foam from the bucket. Remember to add for fiction loss, appliance loss, etc. We ran 300' of 1-1/2" after the eductor to see what would happen. Testing the limitations. It took 5 gallons of foam in the hose before we had foam out the nozzle. With the GPM that you need to flow ARFFF a 5 gallon bucket of foam only last 1 minute tops. Thats running it a the recommended 6%. So you would need a pile of foam and have someone steadily change out pails.
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Permalink Reply by FF Nick on
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Trivia fact for the day with Eductors...
Akron & Elkhart eductors are designed to be used with 200psi for their inlet pressure.
(Taking into consideration approximately a 25psi loss for 200' of 1 3/4" hose and getting 100 psi at the nozzle... that's 75psi in loss for the eductor!)
Of course that is a wittle bitty hole the water has to go through on the eductor. Not having the inlet at 200psi could mean you are wasting a good bit of foam and not getting your maximum expansion.
I'm sure a lot might already know this but I didn't find out till about 4 years ago when I saw the stamp on one of our eductors going through 1002D/O and did some research into it.
http://www.akronbrass.com/uploadedFiles/Products/Foam_Equipment/AB_...
http://www.elkhartbrass.com/files/aa/downloads/catalog/catalog-f-03...
Akron is at the top page 1 and Elkie is bottom page 3.
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Permalink Reply by Ben Waller on
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I remember them, but I'm trying to quit. My department is 6 months from retiring our last 2 conventional eductors. All of our engines have onboard Class A/Class B twin foam tanks with an onboard injection system. Our two quints have our only two eductors, but they will be replaced by two new ones under construction. The new ones will have identical systems to our engines.
The only eductors we'll have at that point are two TFT Pro Paks that we use for hazmat foam blankets, and they educt at the nozzle unless you add the extension hose for the medium-expansion foam mix.
As for the onboard foam being difficult on big spills or fires, it isn't with ours. We just pull our foam trailer up to the pump panel, hook up the foam pickup tube, and draft foam concentrate out of the foam pails into the onboard tanks. We can fill our foam tanks faster than we use the foam since we went with the new National 0.5% "Green" Class A foam and the new National 1% x 3% AR-AFFF "Green" Class B foam.
The eductors had their place, but new foam technology is rapidly moving them from "obsolescent" to "obsolete".
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Ted, we don't have any money, either. Apparently, we spent it all on new engines a while back. :->
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Permalink Reply by Chris on
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Used one just a couple of months ago. Needed foam on 2.5" line and the truck was not piped for foam on a 2.5". The eductor was an 1.5", believe it or not we placed the eductor at the back of a 2.5" stack tip nozzle and it worked fine. We questioned it at first b/c we weren't sure if the venturi effect would work attached to the nozzle. No matter if the truck have foam or not its nice to have around.
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Permalink Reply by Oldman on
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While the "modern" foam systems on apparatus are the "cats meow", I don't necessarily think in-line educators are "obsolete". Years ago in a swift water rescue class, it was drilled into our heads; what do you do when, not if something happens? I have used this phrase in almost every function in the fire service, and foam operations are no different.
If you remove the educators from the apparatus, what are you going to do when the built in system on the apparatus malfunctions? Remembering that anything built by man can fail, there might be an instance where an inline educator can save you a lot of headaches.
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In our case, we'll relay foam from one of our other apparatus with onboard foam or have one of the other engines take over the attack. If that's not possible, we'll get mutual aid from our friendly local ARFF station.
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We have a dual-tank A/B system, so it's not a problem for us. We carry 60 gallons of 1 by 3 AR-AFFF, which is the equivalent of 180 gallons of the older ATC-AFFF concentrate. We also carry 25 gallons of Class A onboard.
We usually start the Class B at 1% (we only go to 3% for ethanol or other polar solvent fires) and we run the Class A at 0.5% for wildland applications and 1% for structural or barricade apps.
We can use our Pro Paks with Class A at 1% and a medium expansion nozzle for barricade apps as well.
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Permalink Reply by Paul Montpetit on
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Well, for one you need extra manpower to monitor and change out the buckets....and if you don't maintain them and clean them after every use they will get clogged up and are a bitch to clean after that happens...best to position then closer to the engine...and you need to check the settings for proper concentration......Paul
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