There are limitations on the amount of water that can be discharged from handheld branches, (typically 1000 lpm), as higher flows have very high back thrust, which makes it impossible for firefighters to handle them safely. Due to this, handline nozzles/ branches have limited range, and hence limited effectiveness.
To fight bigger fires, which give out large amount of radiation, it is necessary to throw water/ foam in sufficient quantity from a safe distance. As explained above, it is impossible to do this using handline branches. Fixed monitors provide the solution as they can project water/ foam further due to the higher quantity of agent, and their design and installation allows the back thrust to be handled safely.
Monitors can be used to project water or fire fighting foam (or in some cases, even Dry chemical powders). Water monitors typically project only water, while Foam monitors can be used to project water as well as foam.
The monitors projecting foam require special nozzles which allow for induction of foam concentrate (and in the case of aspirated foam nozzles, aereation of the foam solution). Thus water and foam monitors differ mainly due to the nozzles which are fitted on the monitor body (while the monitor body remains common for both).
Technically, the monitor nozzle is the part where the foam induction & aeration (in case of primary aspirated foam) takes place. Hence it is possible to convert a water monitor to a foam monitor by changing the water nozzle to a foam nozzle (aspirated or unaspirated).
However, it is important to ensure that the capacity of the foam nozzle is matching to the capacity of the water nozzle to get required performance. Contact the monitor supplier to check suitability. Note : Connecting a Foam branch e.g. FB 10X (450 lpm capacity), at the outlet of a 75 mm waterway monitor (which typically has a flow of around 2800 lpm) will produce only a limited foam range i.e. the range of the FB10X branch only. Such arrangements are not recommended.
Solid jet nozzles are the most commonly used nozzles on fixed monitors in the country. These nozzles project the water in the form of a solid jet stream for long range firefighting, and it is not possible to alter or change this pattern.
Master stream nozzles project water in the form of a hollow jet, which has a better range as compared to solid jet streams, hence these are being preferred nowadays. The other advantage is that the pattern can be changed from hollow jet to narrow fog (for vapour dispersal/ cooling) or wide fog (radiant heat protection).
The range of a Monitor is measured from its installation point to where the majority of the water/ foam discharge falls. However, some standards/ practices measure the distance to the farthest point of the discharge. Range will be mentioned in the data sheet of the monitor.
The ‘effective range’ is not an official definition but gives the actual range of the monitor in real conditions (taking into consideration factors such as unfavourable wind conditions). For e.g. a monitor with a 60 M range would actually be installed at a distance between 35 to 45 M from the hazard, to cater for unfavourable wind conditions, and ensure effective performance.
When deciding the location of a monitor, factors such as the range of the monitor, expected wind direction/ speed, radiation from the fire hazard, site conditions, etc, need to be considered. For better coverage, it may be necessary to provide more than one monitor at different locations – this takes care of fluctuating wind directions and problems of accessibility during actual emergencies. For hazards at a height (e.g. process columns), or at jetties, monitors are also required to be installed at a height (tower mounted) to provide effective coverage.
HVLR (High Volume Long Range) monitors are special application monitors, suitable for high volume applications from a safe distance, ensuring safety of personnel. HVLR monitors find applications where risk of radiant heat from severe fire hazards is high, especially Oil & Gas facilities, flammable liquid storage and processing, ports, etc.
While the monitors can be used for any situation where the application of water or fire fighting foam on the hazard area is required, it is specifically useful for flammable liquid large spills and tank fires. The high application rates from HVLR monitors are more effective in controlling such fires, resulting in lower extinguishing times.
Remote Control Monitors (RCM) are standard monitors fitted with arrangements to operate the same from a remote location. RCMs normally employ Electric or hydraulic motors to operate the swivel joints for vertical/ horizontal movement of the monitor, as well as to adjust the discharge pattern of the nozzle.
RCMs find application in industries/ operations having severe fire hazards, such as Oil & Gas facilities, flammable liquid storage and processing, Ports, etc, where exposing personnel to the high radiant heat/ smoke and gases during fire incidents is not an option. RCMs provide the ideal solution to such problems as they can be operated from a safe and remote location.
In the event of power failure, it is not possible to operate the RCM remotely. However, RCMs are provided with manual standby arrangement to operate the same manually. In this case, the operator has to stand near the monitor to operate the handwheels for the horizontal and vertical movement, as well as or adjusting the discharge pattern of the nozzle.
Portable monitors are employed where far-reaching streams are required but fixed monitors are not available. Portable monitors are normally carried on Fire Trucks (or even smaller vehicles) and quickly assembled and deployed at the emergency scene. Fire hoses are connected to the monitor, and once the hoses are charged, the monitor provides an effective far reaching stream. These monitors are suitable for use with water and foam solution as appropriate to the hazard.
Certain fire hazards require the cooling of large hazard areas using water application. Similarly, it may be required to apply foam over a large area in some situations, instead of specific point application. This can be achieved by using oscillating monitors, as the monitor oscillates in the horizontal plane, providing coverage to a large area instead of a specific location. Oscillating Foam/ Water Monitors use gear boxes and mechanical means to oscillate the monitor in a preset angle. The power for movement can be an external power source or can be aqua powered (i.e. using a small quantity of the water supplied to the monitor). Aqua powered units are preferred as they do not require any external power source. These are also recommended where unmanned operation is necessary in view of severe fire hazards
Location of monitors is dictated by operational requirements such as type of hazard, range of the monitor, wind direction and speed, unhindered ‘view’ of the hazard, etc. When installating monitors, the following should normally be considered –
- The mounting arrangement is suitable to the back thrust from the monitor.
- Ensure that the mating flange of the hydrant post is matching to the valve inlet flange.
- Use approved gasket between flanges, and good quality nuts/ bolts.
- Ensure that full rotation of the monitor is possible, and height of the monitor handwheels are at proper height.
When tested and maintained regularly, monitors will give effective service when called upon to do so in an emergency. Monitors require minimal maintenance, however problems can occur due to entry of stones/ debris into the lines. For foam monitors, the foam solutions used (especially AFFF) are corrosive in nature, and if monitor is not flushed properly after operation, this can cause development of corrosive flakes/ pieces, which may cause problems during operation. Normal maintenance activities include –
- Periodic visual inspections (at least monthly)
- Periodic operational tests (as mandated by manufacturer/ site requirement)
- Proper flushing of foam monitors after operation.
- Greasing of swivel joints at specified intervals.
- Periodic replacement of rubber washers/ gaskets as required by site conditions.
- Periodic painting of external body (as required by site conditions).