A community's fire protection system must have fire hydrants because they give firefighters a steady water supply in an emergency. Cast iron, ductile iron, and bronze are just a few materials used to produce fire hydrants. They come in various varieties, including dry barrels, wet barrels, and flush hydrants. Each is created to fulfil the needs of a particular application.
Introduction
In predetermined areas, firefighters can connect to a water supply through fire hydrants, which are visible connections. Fire hydrants are mandatory in all buildings, parking lots, roadside areas, mines, and industrial zones.
Fires are attacked and put out quickly using water from these tanks. Water flows from a fire hydrant through a pipe with a valve to extinguish a fire. As one of the oldest and most effective and widespread firefighting solutions, the fire hydrant is the backbone of the firefighting system.
Keep reading to learn about fire hydrants, parts of fire hydrant systems, types of fire hydrants and more.
Did You Know?
Until the 18th century, underground fire hydrants were used. Fire hydrants with above-ground pillars became popular and widely used in the 19th century.
What Is a Fire Hydrant?
Fire hydrants are essential to your municipality's smooth operation. Firefighters use fire hydrants to put out fires, allowing them to access pressurised water supplies from water utilities quickly.
Firefighters turn the valve after removing a nozzle or two, attach hoses to the nozzles, and turn the valve to start the water flowing. Based on the hydra's body colour and nozzle type, they can determine how much pressure is available, preventing disasters and property damage.
How Do You Choose the Right Fire Hydrant?
Fire hydrants extend many feet below ground in addition to the portion above ground recognisable to most people. Water and dry barrel hydrants, as well as standpipes, are the two most common types.
Different environments require different hydrant structures and mechanisms. During a hard winter, wet barrel hydrants are more common in parts of the south, where they are less likely to freeze. In contrast, dry barrel hydrants are more prevalent in the north.
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Purpose and Use of Fire Hydrants
The fire hydrant supplies water to suppress a fire. In addition, they are helpful for a variety of secondary purposes, including:
- Line Flushing: Fire hydrants are ideal for flushing main distribution system lines due to their high flow capability and ease of operation.
- Testing System: Using fire hydrants, you can determine the hydraulic capacity of the distribution system.
- Other Usages: Sewer cleaning, commercial construction work, street cleaning, and street construction are other common uses for fire hydrants.
Fire Hydrant System Components
Listed below are the fire hydrant system parts' names.
Firefighting Pumps and Accessories
The pumps that supply water pressure to the fire hydrant system are known as firefighting pumps and accessories. They come in various sizes and capacities and can be either electrically or diesel-powered. Extras include relief valves, pressure switches, and pressure gauges.
Panels
The panels act as the fire hydrant system's command centre. The control valves are housed there, along with other crucial parts, including flow metres, pressure switches, and alarms.
Piping
The network of pipes known as "piping" transports water from a source to a system of fire hydrants. They are typically manufactured of sturdy materials like ductile iron or galvanised steel to endure high pressures.
Landing Valves
The primary control valves for the fire hydrant system are the landing valves. They typically stand close to the building's entrance and provide firemen access to the system's water supply.
Couplings
The connectors that connect the various components of the fire hydrant system are known as couplings. Firefighters can quickly attach hoses and other parts thanks to their quick and simple connect and disengage designs.
Hoses
Firefighters utilise hoses, which are pliable pipes, to send water towards the flames. They are built of strong materials like synthetic rubber or PVC and are available in various lengths and sizes.
Hose Reel
A hose reel is a tool that keeps hoses in storage and releases them as needed. It is often accessible and close to the fire hydrant system's control panel.
Fire Brigade Connections
Firefighters can attach their hoses to the fire hydrant system at fire brigade connections. They often come with a landing valve and a coupler to make connections quick and simple.
Branch Pipes and Nozzles
Firefighters use branch pipes and nozzles to steer water towards the flames. Depending on the purpose, they are available in various sizes and varieties.
Wiring and Instrumentation
Wiring and instrumentation are the components that make it possible to monitor and manage the fire hydrant system. They consist of flow metres, pressure valves, and alarms that notify firemen of systemic issues.
Maintenance Valves
To isolate specific components of the fire hydrant system for maintenance or repair, utilise a maintenance valve. They often stand at key intersections along the system, allowing firefighters to service it without interfering with its normal operation.
Fire Hydrant System – Manufacturing Process
Fire hydrants are primarily made by metal casting, and most hydrant companies also manufacture municipal waterworks components.
The following sequence typically occurs during the manufacture of a fire hydrant.
1. Making the Moulds
A pattern forms the outer surface of a mould. Computers generate hydrant patterns by generating the hydrant's external shape in three dimensions. In stereolithography, the hydrant is formed by hardening liquid plastic using laser beams. This rigid polyurethane piece makes multiple copies of the left and right pattern halves possible.
A core forms the inner surface of a mould. An aluminium or cast iron block is cut into two halves to form a cavity inside a hydrant core. A sand and plastic polymer mixture fills the gap between the two halves. Polymer solidifies the sand to create a core when heated gently. Multiple cores are made by removing a core from a block and repeating the process.
2. Barrel Casting
The hydrant patterns and cores arrive when the mould-making machine is ready to begin a production run. Patterns are pressed into sand-filled moulds to form impressions of the hydrant's outer surface.
A unique mixture of sand is used for moulding that remains in shape without crumbling. A cavity is formed between the core and the impression in one mould half by carefully laying the hardened sand core on its side. Clamping the other half of the mould over the core completes the process. Repeat this process for each hydrant.
Each mould has an inlet passage called a gate during molten metal pouring. The metal flows until it rises through a riser in the opposite direction. Molten metal hardens and cooks polymers in core sand. As a result, the polymer breaks down far beyond its initial set point, allowing the sand to re-enter the system.
Castings split after hardening, emptying the core sand from the mould. It tumbles into a horizontal cylinder filled with small metal pellets to remove any sand or metal bits stuck to the casting. An abrasive cut-off saw removes the cast gates and risers from the furnace.
Handheld power grinders smooth the surface of cast barrels. Casting, grinding, and finishing the head and spool on a two-piece hydrant are separate processes.
3. Valve and Barrel Machining
A shallow concentric groove is cut into the lower flange of the hydrant when it is fixed lengthwise on a lathe. As the hydrant is mounted, the flange seals against a gasket. Drilling the bolt holes in the flange may occur during this process or shortly before shipment.
National Pipe Taper (NPT) threads are cut on the inside and outside of a two-piece barrel to allow the two pieces to connect if the barrel is a two-piece design. The NPT threads are drilled and tapped on one side of the head for a locking set screw.
If it is a two-piece design, the hydrant is rotated cross-ways on a lathe along the centerline of the more prominent outlet or head. The hydrant is clamped into place and counterbalanced as it spins by a rotating fixture.
The lathe bevels the inner surface of the barrel around the outlet opening to provide a smooth seating surface for the valve disc. Valve stem inserts are drilled and threaded into the opening.
Lastly, the outlet opening is threaded. For each outlet, this process is repeated. Each valve stem, valve stem insert, and disc holder is machined and threaded separately.
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4. Hydrant Assembly
After threading the upper valve into the stem insert, an O-ring seal goes over the valve stem. A set screw holds the disc holder, rubber disc, and locking nuts inside the barrel. This is after the inside stem end goes through the opening stem insert.
In the next step, the stem insert fits into the barrel; then, a nut is placed over the outer end of the stem to hold it in place. Each valve operates in the same way.
In two-piece barrels, an O ring over the threaded section of the spool attaches, and the assembled head screws into place. A set screw secures the threads.
Types of Fire Hydrants
There are two types of fire hydrant systems:
1. Wet Barrel Hydrants
Wet hydrants are standard in areas where freezing is not a concern. These types of fire hydrant systems supply water near the surface to the hydrant. At cold temperatures, it is susceptible to freezing.
The wet barrel hydrant is an industry standard wherever freezing isn't a concern, and it lasts for more than 100 years if properly maintained. This is because all mechanical components are above ground.
The hydrant's main feeding exposes its water to freezing despite being close to the surface. As a result of the more fundamental process, they tend to freeze at cold temperatures, which plays an essential role in their survival.
2. Dry Barrel Hydrants
Dry hydrants store water underground. The Earth's temperature is often higher than the cold environment temperature in frigid locations. The design avoids freezing dangers. The dry hydrant system works by firefighters inserting their hose into a valve on top of the hydrant when they need water.
Consequently, the hydrant's drain valve opens. In this way, firefighters can extinguish the fire with water.
Dry barrel hydrants come in three types: slide-gate, compression, and toggle. Dry barrel hydrants have their water valve at the bottom of the hydrant's base. After the water has drained, no water is left in the hydrant's system since it's below the frost line. As a result, there is no risk of the hydrant freezing or becoming damaged by frost.
You can check the water levels at the hydrant's base with a plumb line as part of the hydrant's maintenance cycle. If moisture appears, a malfunctioning drain valve might leave the hydrant vulnerable to freezing.
Standards and Guidelines for Fire Hydrant Systems
National and international organisations provide guidelines and approval for hydrant systems.
1. Organisations that Provide Standards and Approval
- The National Fire Protection Association (NFPA), Indian Standards (IS), National Building Code (NBC), Technical Advisory Committee (TAC), Factory Mutual (FM), and local fire authorities.
2. Components Covered by the Guidelines
- The appropriate pumps, panels, piping, valves, couplings, hoses, hose reels, branch pipes, and nozzles.
- Aspects including water supply, water pressure, water flow, and system testing are also covered.
3. Importance of Adhering to the Guidelines
- Crucial to adhere to the rules and criteria set out by these organisations when building and installing fire hydrant systems.
- Adherence to these standards ensures the system is adequately maintained and functions dependably in an emergency.
Speaking with local fire authorities before building a fire hydrant system is necessary since they can have unique specifications for fire hydrant systems in their region.
Fire Brigade Connection (FBC)
Fire Brigade Connection (FBC) is an independent system that functions like a fire hydrant, offering firefighters easy access to fire protection.
1. Purpose of FBC
- To make getting water to combat fires simple.
- Any fire prevention system must have FBC.
2. Function of FBC
- Provides a stable and sufficient water supply for firefighting activities.
- An autonomous system that functions similarly to fire hydrants.
- Thanks to FBC, firefighters can rapidly attach their hoses to the fire protection system.
3. Components of FBC
- The landing valve and coupling serve as a connection point for the fire department's hoses.
- The landing valve, often found in a box or cabinet, enables firefighters to manage the water flow to the fire suppression system.
4. Importance of FBC
- FBC is a crucial part of the fire prevention system as it gives firefighters immediate access to water for fighting fires.
- FBC must be periodically inspected, tested, and maintained to guarantee it will work properly when required.
Conclusion
Now you learnt all about hydrants, hydrant parts names and types of hydrants. Every critical location has a fire escape hydrant valve. Under the control of a valve, a fire hydrant allows water to flow from the water main into the hydrant.
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