When the solution mixture is correct, adjust the water pattern by turning the nozzle. When you turn the
nozzle clockwise, the stream of liquid spreads out and has less force. Use this adjustment when
contamination is not difficult to remove and when you do not want a lot of splashing. When you turn
the nozzle counterclockwise, the stream of liquid becomes narrow and has more force. Use this
When the task of washing vehicles or equipment has been completed, fully open valve 4 to dump the
detergent. Clean the prime-detergent tank by pouring clean water into it. Add water to the prime-
detergent tank and continue spraying until no sign of detergent appears. Close the ball valve, and valves
1, 2, and 3. Drain and clean the apparatus and stow the components as discussed in earlier learning
Learning Event 2
METER FOAM WITH WATER
In addition to metering detergent with water for washing and decontamination purposes, the M12A1
PDDA can be used to meter foam with water for fire fighting purposes. The foam produced is used for
fighting petroleum or solvent-type fires, such as gasoline, oils, or paint.
For metering foam with water, connect the tank unit and the pump unit with the suction hose as you did
for metering detergent. You will probably have to replace the slurry nozzle with the fire hose foam
nozzle. To do so, remove the fire hoses foam nozzle from the toolbox and remove the gun assembly
from the pump unit. Remove the slurry nozzle as shown in Figure 13. Replace the slurry nozzle with
the fire hose foam nozzle. If both hoses will be used, replace both slurry nozzles. If only one hose is to
be used, the easiest one to work with is the lower discharge hose.
The procedure for adding foam to the prime-detergent tank differs somewhat from the procedure for
adding detergent. To add the foam, proceed according to the following steps.
Step 1. Prime, start, and operate the pump unit as learned in previous lessons.
Step 2. Be sure valve 4 is closed and the prime-detergent tank contains no more than two inches of
water. If the prime-detergent tank contains more than two inches of water, you must lower the level to
two inches by
Opening valve 4.
While observing the water level in the prime-detergent tank, slowly opening the pump drain valve.
Quickly closing the pump drain valve when the water level falls to two inches.
Closing valve 4.