The fire fighting system is crucial for every business. Because a sudden fire event can be highly damaging to buildings, expensive equipment, documents, and inventory. Water sprinklers, smoke detectors, and fire suppression mechanisms are all part of a fire fighting system, and they all heavily rely on top-quality, highly-efficient valves to safely provide the right amount of water at the right time. Valves are the critical components of every system which involves the transport and supply of fluids. As water supply is essential in a fire fighting system, the piping must have suitable valves for accurate control of flow.
In this guide, we have discussed some important types of valves in fire fighting system, which are:
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- Butterfly Valve
- Check Valve
- Angle globe valve
- Gate valve
- Ball valve
- Relief valve
1. Butterfly Valve
Butterfly Valve acts as a control valve that starts and shuts the flow of water to the pipes in fire fighting systems. It has an internal disc that rotates to control the movement of water. A position indicator is also attached to the valve, which helps the firefighters to confirm whether the valve is opened or closed. The design of the butterfly valve is simple, consisting of only four main parts, including body, seat, stem, and disc.
Butterfly valves come in a wide range of sizes, pressure ratings, and temperature ratings. These valves are available for pipes as small as 1 inch and as large as 12 inches in diameter in fire fighting systems. While most of them have pressure ratings up to 300 PSI. The wafer, threaded and grooved butterfly valves are commonly used in fire protection systems.
2. Check Valve
The check valve in fire fighting systems prevents the backflow of water. It features a hinged clapper that only moves in one direction. It keeps the valve closed until flowing water opens it, and when this flow reverses, the clapper contact with rubber seat to form a tight seal. Additionally when there are multiple water sources, the check valve determines which source will supply the water to the system. Four types of check valves are used in fire fighting systems, which are:
- Swing check valve
- Grooved check valve
- Grooved shotgun riser check valve
- Alarm check valve
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The alarm check valve and riser check valves are need to be checked more frequently. While the clapper and valve seat should be inspected regularly to ensure the proper seal.
3. Angle globe valve
Angle globe valve is a variant of the traditional globe valve that is used at varying angles in the pipeline. The angle of the valve is decided according to the requirement of the application. In most cases, this valve is used at an angle of 90 degrees to the pipes. The angles allow the applications to minimize the coefficient of the flow than in usually patterned valves. It holds a plug which is raised and lowered to open and close the valve, respectively.
In the fire fighting system, an angle globe valve is used to regulate the water flow instead of starting and stopping it. It is available in various dimensions, with the size ranging from 2 inches to 18 inches. Moreover, the pressure ratings also vary from application to application. Typically, the pressure ratings in the angle globe valve are 150 to 2500 PSI.
4. Gate valve
A gate valve is a bidirectional valve that uses a rectangular or round gate to control the flow. They act as control valves in many fire fighting systems. Gate valves do not offer obstruction to the flow path in the opened position, which results in a very low-pressure drop. However, they can only be used to start and stop the fluid flow and not for throttling services. They are operated by a handwheel in a counter-clockwise direction to open and clockwise direction to close the valve.
Gate valves have a simple design but also come with a number of variations, such as the rising stem type, and the non-rising stem is connected to the actuator. In rising stem valves, the stem threads meet with threads in the bonnet, the stem rises above the actuator, and the valve opens up. While in non-rising type, stem threads mate with disc threads, and the valve opens and closes without raising the stem.
5. Ball Valve
The ball valve is also common in pipes supplying water to fire protection systems. It is a shut-off valve that manages the water flow with the help of a rotary ball with a bore in it. A quarter-turn rotation of the ball around its axis block or allow the flow. Moreover, the ball valve is durable and function to provide a watertight seal over the years.
Ball valves come in a variety of sizes to suit different applications; usually, they range from 0.5 cm to 121cm. However, using them for throttling applications will damage the ball valve seat. Some versions of ball valves are also used as control valves, but they are not used so frequently due to limited precision as compared to other control valves.
6. Relief valve
Relief valves are installed to prevent damage to fire pumps due to overpressure. Fire fighting systems normally use diesel and electric pumps. It must be installed where the diesel engine turns faster than normal because the pressure is directly proportional to the square of the pump’s speed. Moreover, these valves are also installed in electric fire pumps where a variable speed drive is used.
The relief valve is built to open at a preset pressure and stays open until pressure drops to safe levels. In fire pumps, it directs water from the pump’s discharge back into the pump’s inlet when pressure surges occur. Plus, they are designed in a variety of configurations and end connections for broad applications.
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