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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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Every pump is outfitted like this Ben?
Quite nice if they are for you. You just don't typically see pumps outfitted like this currently and a foam eductor is a simple way to supply foam. For us, we have only 2 pumps that have class "A" foam, every other pump has ATC foam and an eductor, well even the new pumps too because they are only outfitted with class "A".
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Permalink Reply by Paul Montpetit on
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Hope and pray it isn't an ethanol fire....you probably don't have enough AR-AFFF foam in the whole county to put out one supertanker (12000 gallons ethanol)
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Permalink Reply by Ben Waller on
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We don't have to put it all out - just the surface area. :-)
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We have eight identical engines with the twin-foam system. We have two older quints which still have in-line eductors. The replacements for the two quints are under construction. When they are placed in service, we won't have any in-line eductors except for the TFT Pro Paks on our hazmat unit.
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The two rows of red lights to the pump operator's left are the Class A and Class B foam tank level indicaters. Class A concentrate is 2.5 gallons per light, Class B concentrate is 6.25 gallons per light.
It's difficult to tell in this shot, but the light between the two foam tank indicators is a flow meter. All preconnects are piped through it, so we can measure actual GPM flow for water, Class A foam, or Class B foam through a 1-3/4 bumper line, two 1-3/4 crosslays, and two rear 2-1/2 preconnects.
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Permalink Reply by Colin Carswell on
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These dinosaurs are used by my company everyday!! We have 150 gal of 1x3 AR-AFFF concentrate on all of our trucks with additional foam a phone call away. The nice thing about them is that are very simple to use as long as you make sure your inlet pressure is correct and your flow rate is the same at the nozzle as it is at the eductor (these should both be stamped on the eductor). If your pressure is to low the venturi effect will not work, and if the flow rate is less at the nozzle than at the eductor the back pressure created can negate the venturi effect. The rule that we use is 200-250 psi in, and no more than 150'-200' of 1"1/2 beyond the eductor. Like others have said here, maintenance is key to these, look after them and they'll look after you.
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Onboard systems don't require matched nozzles and eductors, because the injection systems are balanced and don't rely on the venturi effect in order to operate.
The onboard systems don't requre a minimum flow - if you set the proportioner to 1%, you'll get 1% if you're flowing 25 GPM or if you're flowing 250 GPM.
No back pressure problems.
No specified hose footage between the eductor and the nozzle.
Maintenance is minimal - just flush with clean water after using.
I'm not saying that the eductors don't work - they do.
I'm just saying that there's a better way to do it.
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Ya I do agree that are much better methods of making foam than the eductors, especially in the municipal Fire departments.
I'm on the Industry side of firefighting now where we are often in remote locations in some pretty harsh...cold conditions and eductors can take a lot of abuse!! The thing I like about them is that they are very reliable as long as you use them properly...low-tech technology.
We do run the proportioner's on our 2000+ GPM monitors and our bigger pumps to make sure that we get the proper percentage on delivery.
Unfortunately our industry is far too safe as of late and has taken all the fun out of our job!! I guess our Health & Safety personnel industry wide are doing to good of a job with prevention!!
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The same goes for onboard proportioners or injectors. Lots of post-use flushing makes the foam system a happy foam system.
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Permalink Reply by Luke Summers on
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Wow those are to ones we still use on our front line units.....and im pretty sure they are from the 60's, they do work but they get clogged real east if you dont flush them out, spent a whole afternoon breaking one down to get it working again.
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