MONITORS

Caution Potential Hazard Equipment Misuse can Result in Serious Injury

WFR strongly recommends that fire personnel carefully develop operational procedures for this type of equipment based on the manufacturers' data and the fire personnel's own experiences in direct field operation.

Stationary Mounted or Fixed Monitors (Fig. 1)
As a result of the jet reaction force, a shear force and a significant over-turning moment will be developed at the mounting base of a stationary installation. The over-turning moments become particularly significant for elevated monitors since an extended lever arm is involved, resulting in high moments at the unit base. In most cases involving elevated monitors it is recommended that some engineering should be involved in the base mounting design. WFR has developed some data on the elevated units.

Portable Units (Fig. 2)
Particular attention must be given to portable monitors since the resistance to their reaction jet forces must be developed by friction with the ground surface at the point of use, (e.g. dirt, grass, asphalt, concrete, etc.) and/or the addition of some sort of outside restraint, (e.g. chain, hose lay, etc.). A wheeled portable trailer must have lockable wheels, wheel retraction mechanisms, etc. to ensure a high friction contact with the ground surface.

A portable monitor's vertical depression angle should be limited mechanically by a device so that a significant vector of the jet reaction force can add to the ground friction (e.g. the angle of elevation should not be less than +20 to +25 minimum above the horizontal plane). On WFR equipment the depression angle limit can be over-ridden for special cases, but the operator must be instructed in its proper use and limitation due to the potential hazard and its serious consequences.

The TFT Crossfire with the SAFE-TAK base eliminates the danger of movement of this portable monitor. It has also been suggested that hose lay to the portable monitor should play a role in resisting the jet force. If the hoses come in from the front of monitor they will offer resistance by dragging the hoses over the ground surface. Whereas if the hose lay comes in from the back-side of the monitor (opposite the water flow and the fire) they may tend to buckle under the load and offer little if any resistance. Since this type of resistive force does not come into play until the portable monitor actually starts to move it may not be a viable consideration.

Ladder Mounted Units
As with the elevated monitors, shear forces and significant over-turning moments due to the extended lever arms will be developed (Ref. 1). The design and use of ladder mounted monitors and supporting equipment require careful engineering from the start and thoughtfully developed and rigorously followed operational procedures to ensure safe equipment operation.

Summary
Water discharge from a nozzle produces a large reaction force, which can present a hazard to the operator or personnel in the vicinity if proper provisions and procedures are not in place to resist this force. All locks provided on the equipment must be engaged and secure prior to initiating the flow of water through the device. Jet reaction force limitation labels are located on the various devices as applicable and must be observed and the instructions rigidly adhered to at all times. If there are any questions or data required, please contact our office.

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