It has happened again: a deck gun was “launched” several feet in the air from the top of a fire apparatus when its pawls or teeth did not properly engage the groove in the pipe connected to the pump discharge. Fortunately, no one was struck by the falling device.
Miami-Dade (FL) Fire Rescue‘s master stream devices have the capability to convert an apparatus deck gun to a ground monitor by disconnecting them from the pump discharge piping at the top of an apparatus and connecting it to a portable base. For most of the appliances, disconnecting the device requires three simultaneous actions: pulling a pin, twisting the grip handle, and lifting the device. It is CRITICAL to ensure that the pawls or teeth are fully engaged in the groove of the ground monitor base or pump discharge piping. Although purely supposition, it is believed that in this latest event that the pin may have been stuck in the “pulled” position. A secure connection can be ensured by vigorously pulling up on the device’s grip handle when connecting to pump discharge piping or ground monitor base. When on the ground, firefighters should stand clear of the device when it is charged. Additionally, pump operators, when possible, should keep a close eye when “sending the water” to the device. Water leaking at its connection with pump piping or its ground base is a strong indication that the device is not securely connected. Rubber Ceramic Chute Liners
There are four hazards associated with master streams:
1. Firefighters struck by a master stream can be severely injured, especially if they are knocked off of a ladder or roof.
2. A master stream can strike objects, such as roof tiles, sending them airborne. At a fire started by roofers, a stream from a ladder pipe struck large rolls of roof membrane, sending them flying off of the roof; barely missing firefighters operating on the ground. Similarly, a rotary saw used to cut holes in a rain roof was struck, sending it to the ground.
3. Firefighters may lose control of a ground monitor when they direct a stream below the recommended elevation, approximately 32-35 degrees, depending on the particular device. As the angle of a stream is lowered, the nozzle reaction that forces the device to the ground changes to a horizontal force, causing firefighters to lose control. Some devices have a safety stop to keep the angle of the stream from being directed below a safe angle. When the device is connected to pump discharge pumping on top of an apparatus, nozzle reaction is not a factor. Hence, the angle of the stream can be lowered by pulling a pin. It can be tempting for firefighters operating a device on the ground to pull the pin to lower the angle of the stream or worse, placing a roll of 1¾-inch hose under the back legs of the ground monitor base.
Portable monitors are defined as devices that can be moved when connected to a hoseline(s) when they are not flowing water. Portable monitors are required to be equipped with an anchor strap to keep them from sliding. If there is no substantial object within reach of the strap, loop a hoseline supplying the device around and in front and fasten the strap, using the weight of the of the charged hose as an anchor.
Additionally, be sure to take out any slack in the strap between a ground monitor and hoseline. Two additional practices to avoid uncontrolled movement of ground monitors are: Pump operators must charge hoselines supplying a device slowly; similarly, firefighters operating the device should do the same when they begin flowing water. Additionally, keep 10-feeet of the hoselines supplying a ground monitor straight back behind the device.
4. A 500 gpm master stream directed into a building amounts for over two tons a minute. This increase in live load is especially dangerous when contents absorb water in sufficient quantity to collapse floors, mezzanines, and rack storage.
Mosaic Tile BILL GUSTIN is a 49-year veteran of the fire service and a captain with Miami-Dade (FL) Fire Rescue. He began his fire service career in the Chicago area and is a lead instructor in his department’s Officer Development Program. He teaches tactics and company officer training programs throughout North America. He is a technical editor and an advisory board member of Fire Engineering and FDIC International.