Refresh your foam-flowing skills
Foam operations are few and far between for most of us. Unless it's pre-plumbed on the apparatus, it's the last thing we think about — until we're at a flammable-liquids fire.
This month's drills provide a quick refresher on using the eductor, cleaning the eductor and making lots of foam when necessary.
Drill 1, Step 2 |
DRILL 1: USING THE FOAM EDUCTORSetting: An area where you can flow copious amounts of water
Duration: 30–60 minutes
Equipment needed: Apparatus, foam eductor and training foam (or a few 5-gallon pails/buckets and some food coloring)
Objective: Demonstrate the skills necessary to set up and continue a foam operation.
Step 1: Gather all the equipment at the pump panel or one length of hose away from the apparatus.
Step 2: Mix the foam; if you use food coloring in place of foam, add it to the water. In the picture shown above, we used water and food coloring. A little dab will do: We used less than a tablespoon of coloring for a 5-gallon bucket.
Step 3: Using any needed adaptors, connect the eductor to a discharge and to the attack line. Alternatively, you can connect the eductor in-line on a preconnect.
Drill 1, Step 3 |
Step 4: Ensure the foam eductor and nozzle are set at the same gpm flow. The flow rate for the eductor should be stamped or embossed clearly on the eductor.
Drill 1, Step 4 |
Drill 1, Step 5 |
Step 5: Set the metering valve to the desired ratio.
Step 6: Start the flow. Remember: Most eductors require 200 psi at the inlet for as close to an exact proportioning ratio as you can get. Watch the foam bucket: When using either training foam or water with food coloring, the bucket will empty faster than with regular foam because of the difference in the liquids' viscosity. AFFF or other foam is thicker than water or training foam. (Be prepared: You'll be swapping pails of AFFF or other foam at the rate of one pail about every 80 seconds at a 3 percent setting, and faster at 6 percent. If you face a big foam job, it may be best to pour the foam into a large ice chest or other container. Ensure the eductor's pick-up tube will reach the bottom.)
Drill 1, Step 6 |
Drill 2, Step 1 |
Drill 2, Step 2 |
Step 7: Disassemble the foam operation, and return the apparatus to service.
DRILL 2: CLEANING THE EDUCTOR
Setting: In the station
Duration: 30 minutes
Equipment needed: Water, foam eductor, washcloth, low abrasive scouring pad, tubing brush and — depending on your eductor — a pin spanner wrench
Objective: Demonstrate how to clean the eductor so it does not clog and is ready for use.
Step 1: Unscrew the metering valve.
Step 2: If your eductor uses a metering ball, be careful not to let the metering ball fall out and get lost. You may need a pin spanner to remove the orifice that holds in the ball.
Step 3: Flush the eductor and the pick-up tube with copious amounts of water.
Step 4: Clean the meter, metering ball and area of built-up foam gel. You may need a tubing brush. Inspect all components for cleanliness.
Step 5: Reassemble the foam eductor. Work the meter to ensure it still turns after reassembly.
Drill 2, Step 4 |
DRILL 3: SETTING UP AND AROUND-THEPUMP FOAM SYSTEM
Setting: An area where you can flow copious amounts of water
Duration: 30 minutes to an hour
Equipment needed: Apparatus, foam eductor, training foam or a few 5-gallon pails/buckets and some food coloring and a 2.5" male to 1.5" female adapter
Objective: Demonstrate the ability to set up an around-the-pump foam system using a standard foam eductor.
Step 1: Set up the training foam following the manufacturer's directions, or fill a few pails/buckets with water and food coloring.
Step 2: Remove all but one section of hose from a preconnected line, or use a section of hose and an adapter off a side discharge.
Drill 3, Step 3a |
Drill 3, Step 3b |
Drill 3, Step 3C |
Step 3a: Attach the 2.5" male to 1.5" female adapter to the 2.5" suction on the apparatus. Attach the discharge side of the eductor to the intake and the end of your preconnect to the intake side of the eductor. (Obviously, if you use a 2.5" eductor, you don't need an adapter on the pump intake.) Alternately, you can attach the eductor to the intake using whatever adapters your department owns.
Step 3b: If you prefer, you can use another section of hose between the discharge side of the eductor and the intake of the pump. This moves the foam-making operation away from the pump panel and out from under the engineer's feet.
Step 3c: You can also attach the eductor straight to a discharge and route the hose into the 2.5" intake.
Step 4: Close the tank fill valve if it's open.
Step 5: Use the deck gun and/or other discharges and start flowing the foam. Using a 125-gpm eductor set at 3 percent, you can deliver Class A foam at 0.5 percent at about 750 gpm and at 1 percent at about 375 gpm. If you set the eductor on the 6 percent setting, you'll get Class A foam at 0.5 percent at 1,500 gpm and 1 percent at 750 gpm. To deliver Class B foam, set the eductor at 6 percent and you'll get 3 percent foam at 250 gpm.
Step 6: Clean the eductor as described in Drill 2 or by following the manufacturer's instructions.
Technical Editor Scott Cook is chief of the Granbury (Texas) Volunteer Fire Department.
