A fire hydrant system is emergency equipment meant to assist the fire department in case of a fire outbreak. Fire hydrant installation is a safety requirement on streets and in some buildings to provide immediate aid.
Fire hydrants consist of several components assembled to serve the purpose of providing a water source during fires. These water sources are connected to a network of valves that provide enough flow and pressure to supply water immediately.
For higher efficiency, fire hydrant installation is done in association with other emergency systems like automated fire sprinklers and fire hose reels.
The building code of Australia (BCA) has a strict Deemed-to-Satisfy (DTS) policy for fire hydrant installment. The DTA requires the buildings to maintain a fire hydrant system that conveniently facilitates the water supply requirements of the fire brigades in cases of fire. The hydrant system must assist in fire-fighting operations, controlling fire hazards, and covering the floor area of the building.
Therefore, a fire hydrant system is designed in a way that achieves those objectives and provides timely assistance. The primary objective that is kept in mind while designing a fire hydrant system is its pressure and flow. This is especially more important for hydrants in hydrologically disadvantages areas.
The requirements of the flow and pressure for a fire hydrant depend on the building it is going to be installed in, the area of the flow, and the sprinkler protection. Consultancy with a certified fire protection specialist helps in figuring out the right type of setting for a fire hydrant in a particular area.
Types of fire hydrants
Fire hydrants are categorised into the following two types:
1. Dry barrel hydrants: Dry barrels are popular in areas that have very cold and freezing temperatures as there is no water in Dry barrel hydrants above ground. They provide insulation by using depth to prevent the freezing of water supply.
2. Wet barrel hydrants: This type is more common in dry and hot areas. These hydrants are water-filled all the time. Wet barrel hydrants usually have multiple operating stems that run horizontally to each outlet.
Components of a fire hydrant system
The Australian Standard AS2419 requires the design of the fire hydrant systems to consist of the following essential components:
● Water storage and supply
● Valves and pipework
● Fire brigade booster
● Hydrant valve, hydrant, or landing and coupling valve
● Block plan
1. Water storage and supply
The primary requirement of a fire hydrant is a reliable source of water supply. The water is usually supplied by either street main or fixed sources like a dam or a tank.
Another critical component is water storage. It must have the ability to automatically replenish and make up for the water loss due to leakage, evaporation, and periodic testing. Therefore, the hydraulic analysis should also account for the volume and capacity of the storage and supply of water.
2. Valves and pipework
A fire hydrant comprises a series of interconnected pipes of varying specified sizes to channel the water from its source of supply to the hydrant valve. Hydraulic analysis and the Australian Standard AS2419 determine the required dimensions of the pipe.
The control valves are installed in a way that they work with the pipework to direct the water flow.
3. Fire brigade booster
The fire brigade boosters provide an attachment point for the fire personnel to get extra water for a fire hydrant system in case of emergencies. The accessibility of fire brigade boosters must be ensured so that the firefighters can easily use it for protection.
Fire brigade boosters are usually installed in a compartment that has the details regarding the requirements and pressure limitations of the respective fire hydrant system.
If a hydraulic analysis determines the insufficient supply of water for a particular building’s requirements, then one or a few booster pump sets are to be installed.
Pump sets usually consist of a combination of compression or electric ignition motors.
5. Hydrant valve
The finishing end of the fire hydrant is a hydrant valve, also called a landing valve, or simply a hydrant. In accordance with AS2419, the hydrant is meant to be located at different points across a building. Typically, the diameter of a hydrant valve is around 65mm.
However, the fire hose connection requirement varies according to your specific location in Australia because different fire brigades use different hose connections. Therefore, the hydrant valve should be fitted with a coupling that is compatible with the fire brigade of the concerned location.
It is essential to maintain the fire hydrants in accordance with the AS2419 regulations. They must also be easy to access to prevent a delay in assistance.
6. Block plan
The block plan is a permanent diagram displayed inside the booster cabinet, fire control room, and pump room of a fire hydrant system. It illustrates the main features of the fire hydrant, including the following:
● Location and capacity of water storage
● Location of water source
● Quantity of valves
● Pressure and flow rate
● Location of pumps
● Location of the electrical control room
● Location of inflammable areas
● Installation contractor’s information
● Year of installation
● Height of the tallest fire hydrant
● Size of the lowest booster connection
How do fire hydrants operate?
When a firefighter opens a hydrant valve, the water pressure drops in the hydrant system. The pressure drop is then detected by a pressure switch that operates the booster pumps. The water is drawn from the supply to compensate for the pressure drop.
This water is then channeled to a nozzle and is sprayed on the outside fire. Fire brigades might also add additional water to boost the water pressure to fulfill the requirements of the situation. They do this by attaching the fire appliance between the booster connection and an alternate water source.
A fire well is used for the storage of water throughout the year. The water is efficiently connected to the pump room. The pump room is connected to a network of pipes covering the entire building. The pump is responsible for maintaining the pressure of 7 to 10 bar in the pipes.
Ken Thomas is the director at Total Fire Solutions, leading fire protection services providers in the Pacific Rim and one of the top 3 independent distributors for the Asia Pacific region. His vision is to create a ‘one stop shop’ fire protection company committed to NSW mining and heavy industry. He is passionate, innovative and excited by the latest developments in fire protection technology.