2. Carried By: Fire Pumping Apparatus, Engine Companies; and Crash Rigs = 51, 80, 90; Foam Carriers = 34, 53, 86, 100; Fire Boats 2 and 4
3. Purpose: Used in conjunction with 5 gallon containers of AFFF and ATC when applying foam to flammable liquid spills and fires.
Description:
a. Produces "mechanical" air foam by drafting liquid, AFFF, low expansion foam concentration from a container.
b. Mixes the foam concentrate with the incoming water stream.
c. Entrains outside air which mixes with the water/foam solution to form a foam consisting of millions of tiny air bubbles.
d. Nozzle is the "aspirating type" in that air is aspirated or mixed with the liquid water/foam solution at the nozzle.
4. Components:
- Inlet Strainer; Female Swivel, 1 ½" NST
- Jet - Butt Assembly
- Base Casting - Diverter
- Nozzle Barrel - "Tear Drop" Restrictor
- Discharge Tip - Pick-up Tube Connection
- Flexible Pick-up Tube - Strainer
- 3/4" Garden Hose Thread - Pick-up Tube Inlet
Usage:
- Pre-mix in the Tank; 50 gallons to 400 gallon tank.
- Wagon Battery; 100 psi @ nozzle, 65' reach and 75 gpm.
- Hand Line; 1½" hose, shut off butt, attach Foam Nozzle.
Supply 100 psi @ nozzle, 50' reach and 60 gpm.
5. Operation:
Eductor System
- Butt end of the nozzle is provided with an "eductor" to siphon foam concentrate from containers.
- Incoming water flows through a converging jet or nozzle into a spreader housing where a vacuum is created.
- This drafts concentrate from the container through the pick-up tube, through a metering orifice to provide the correct proportion of water and foam.
- The nozzle is provided with a standard drilled 1/4" orifice, permanently installed, for using 6% foam concentrate; only orifice to be used.
- Foam inlet and pick-up tube are provided with a 3/4" garden hose thread. (Pick-up can be extended with 3/4" garden hose up to 50' provided the couplings are in good condition and do not leak air.)
- Strainers provided in the 1½" inlet and at the inlet end of the pick up tube.
Diffuser
- Cone-shaped device installed in the waterway.
- The point facing the incoming stream which spreads or diverts the stream into a conical or spread pattern so that the stream will hit the interior circumference of the barrel.
- A shielded air inlet to the barrel is provided at the butt end of the nozzle.
- This diverging stream picks up air by friction and mixes it with the water/foam solution within the barrel and forms tiny foam bubbles.
Restrictor
- A "teardrop" shaped restrictor is provided in the center of the barrel near the tip end to adjust the flow at the center of the stream.
- Causes the center of the stream to travel at an equal velocity with the outer portion so that the entire cross- sectional area has the same velocity as it leaves the nozzle.
OPERATING CHARACTERISTICS:
The nozzle has an effective nozzle diameter (jet orifice) of .450" for computing water flow. The minimum operating pressure at the nozzle is 50 psi. The approximate flows are shown in the following table:
Adaptations:
- The nozzle can be used without the pick-up tube when pre-mixed water foam solutions are available from in-line eductors or mixing systems.
- Crash Trucks or Fire Boats have either in-line eductors or mixing systems.
a. Plug the pick-up inlet with 3/4" garden hose thread plug.
b. If mixing system has sufficient capacity, the eductor jet can be remove to provide greater flows.
c. Without jet nozzle, device will deliver 75 gpm @ 75 psi.
6. Additional Information
- Use the shut-off butt to control the flow, particularly when in-line eductors are used and water flow may exceed capacity of eductor to pick up concentrate.
- The shut-off butt should be closed slightly to provide the best foam.
- Currently only Fireboat companies use the foam nozzle for dispensing protein foam solutions.
7. Maintenance
- The nozzle and pick-up tube shall be flushed with fresh water after use.
