A control valve is a power operated device capable of regulating the rate of water flow in response to an actuation, or a signal from the controlling system. These devices can be used to control a system’s water supply, affect the direction of water flow, and control the amount of water that flows from one area to another. At its core, the control valve allows you to customize and gain complete control over your water supply and suppression system. Some valves are even able detect water flow and send alarm signals. These control valves come with different designs to perform all of these functions. Keep reading to learn more about the different types of control valves.
Cavitation occurs when liquid in a valve is vaporized and form air bubbles in a pipe due to localized low-pressure zones. Subsequently, the sudden condensation of the vaporized liquid downstream often causes pitting and damage in your pipes along with a distinct ‘popping’ sound. These low-pressure zones can be created in shutoff valves nearing full closure, especially when upstream pressure exceeds 100 psig. As water flows, through a partially closed valve, pressure is increased at the smaller openings and simultaneously decreased just behind the closing mechanism, creating air bubbles. Some valve designs are inherently more vulnerable to cavitation due to how they regulate flow and close under pressure.
Due to the damaging effects of cavitation on your fire suppression system, it is important to stay on top of regular system maintenance. Performing frequent visual inspections are extremely important to find any signs of cavitation. According to NFPA 25, standard for the Inspection, Testing, and Maintenance of Water-Based Fire Protection Systems, you should inspect your control valves visually on a monthly basis. However, when it comes to cavitation, damage may occur further down the piping when air bubbles in the system pop. Therefore, you should visually inspect your piping and fittings for any signs of erosion or cavitation as well during your system inspections.
Cavitation damage evident on a watercraft propeller. Photograph by Erik Axdahl.
Valves used in fire suppression systems come in numerous configurations, with different body types, materials, connection methods, and sizes to suit diverse requirements. Choosing the right valve depends heavily on operating conditions, system demands, and expected flow characteristics. Here are options that are commonly found in systems in the field.
Designed for simple and fast actuation, these valves provide tight shutoff to water flow. That is, they don’t allow any water to leak even when under high pressures. Conversely, the valve creates little to no resistance to flow when in the fully open position. These valves should never be used to control flow by partially closing the valve, as this can lead to wear on the device. Additionally, while these devices are effective and low cost, they are prone to cavitation.
Butterfly valves are widely used in fire protection due to their fast response time, dependability, and frequent operation. As such, they can be found in sprinklers, standpipes, and hydrants, where water supply is rapidly delivered to deal with fire emergency situations. These are designed with a disc that rotates around a shaft, supported by bearings to enable smooth movement. This design means they do not enable a tight shutoff, but they can be used to control flow volume and pressure. Meanwhile, when fully open, the valve provides very little resistance to water flow.
A globe valve features a movable disk element and a stationary ring seat housed in a spherical body. By adjusting the valve stem, the globe plug moves relative to the seat, providing gradual control over the flow rate between fully open and closed positions. These valves are ideal when you require precise flow regulation and wide throttling operations, but not for high-capacity demands.
A gate valve contains a linear stem that raises and lowers to facilitate the opening and closing of the valve. This type of valve is best for infrequent operation and provides tight sealing of the pipe. Also, this cannot be used for throttling and may cavitate at low pressure drops.
An actuator is a device that is often used alongside valves for opening and closing of the device. These are operated with electricity and may mechanically turn valves to the fully opened or fully closed positions. More modern actuators can turn valves to intermediate positions with high accuracy for precise control over the flow rate. Even more, there are two different types of actuators—pneumatic and electric.
By receiving an air signal from a remote control device, pneumatic actuators initiate a control response via a solenoid.On the other hand, Electric actuators rely on an electric signal to drive a motor, which causes a shaft to rotate the valve into an open or closed position.
A pressure relief valve is used to protect systems from excessively high pressure levels. Thus, a pressure relief valve is typically set to open at the safe pressure threshold. When the system’s pressure reaches or exceeds this threshold—often due to a surge in water or foam flow—the valve opens, allowing fluid to escape, thereby reducing fluid to a safer level. By maintaining safe pressure levels, this valve ensures that the system operates effectively at all times.
These are two-way valves featuring one port for fluid intake and another for discharge. These valves allow flow in one direction only, are self-closing, and have a low pressure drop when open. Typical types include swing-type, spring-assisted, ball, duckbill, clapper, silent models, and more.
Control valves play a vital role in the effective operation of fire suppression systems, offering precise regulation of water flow, pressure control, and the ability to direct or stop the flow as needed. Each valve type is designed for specific use-cases, so it is important to select the right valve depending on the unique demands of your application. Understanding how all of these devices work to protect and regulate your system helps you to make better purchase decisions when designing your system. Whether managing water pressure or controlling flow, the proper us of these components is essential for reliable and effective fire protection.
Are in you interested in purchasing control valves or replacement parts for your fire suppression system? Explore our stock of commercial ball valves, actuators, pressure relief valves, check valves, and much more.
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