Guide to Check Valves for Fire Protection

Pressure-activated check valves prevent contamination and flooding from water sources used in fire protection systems

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A check valve is a device that permits the flow of semisolids, liquids, or gases in only one direction. Check valves, featured in systems ranging from residential plumbing to pharmaceutical production, often rely simply on changes in pressure to manage flows.

In this article, we’ll focus on check valves for fire protection, discussing how they work, the types of check valves, and their benefits in fire sprinkler systems. Additionally, we’ll help you understand what components you should look for when selecting a check valve and discuss how to maintain them.

Already know what you need? Feel free to go straight to our check valve product page and selection of grooved riser check valve trim kits.

How does a check valve for fire protection work?

Each fire sprinkler system needs a dependable source of water for immediate use in a fire emergency. Most systems use some combination of gravity tanks, municipal water supplies, and sometimes fire department connections to provide water to sprinkler heads. But while multiple potential water sources provide an extra layer of reliability to fire protection systems, they can also be problematic: drinkable water might be contaminated by water from a fire hydrant, or dirty water from fire sprinkler pipes might flow through nearby streets and into nearby drains. In many other applications, it’s simply important that water only goes one way for performance reasons. These include protecting equipment such as pumps and filters from backflow damage, stopping drainage in a fire sprinkler system with elevation changes, providing pressure relief in liquid or pneumatic applications, and more.

Check valves for fire protection prevent the unwanted reverse flow of water, known as backflow, from occurring. Many check valves feature a hinged clapper with a spring, which keeps the valve closed until the water flowing from some water source opens it. These clappers only open in one direction: when these flows reverse (or very nearly stop), the spring presses the clapper against a rubber seat, forming a water-tight seal.

Think of the water on either side of the clapper as the supply side (between the water source and the check valve) and the system side (between the check valve and the rest of the system). When a fire sprinkler head discharges, water is released, decreasing the pressure on the system side. Shortly after, the higher pressures from water stored or pumped from the supply side push open the clapper, and water flows through the system.

How does a check valve for fire protection prevent contamination of potable water?

When multiple water supplies serve the same fire sprinkler system, each must have a check valve.

From the 2022 Edition of NFPA 13

16.9.4.1 Where there is more than one source of water supply, a check valve shall be installed in each connection.

Check valves decide which source actually provides the system with a supply of water at a given moment. When multiple water sources are used simultaneously, only the check valve connected to the highest-pressure water source remains open. Imagine you have a system with three water sources at the following pressure ratings, expressed in pounds per square inch (PSI):

Active Water Sources Check Valve Status   100 PSI Fire Department Connection (FDC)
75 PSI Gravity Tank
50 PSI City Water
FDC, Gravity Tank, & City Open Closed Closed Gravity Tank & City Water Closed Open Closed City Water Only Closed Closed Open

(Note: these pressure levels are provided only as illustrations and are not meant to be taken as typical for these water sources.)

When water is supplied from all three sources, only the check valve leading to the fire department connection remains open. Why?

Of these three sources, the FDC delivers the highest water pressure. This supply pressurizes the water on the system side. This increased system-side pressure is greater than the 75 or 50 PSI on the supply side of the check valves connected to the other water sources and, as a result, their clappers close.

To continue with this example, if only the city water and the gravity tank supply water, the check valve to the 75-PSI gravity tank will open, while the city water’s check valve stays closed. Only when all other sources are exhausted or closed does the municipal water supply open the check valve and flow into the system.

What are the types of check valves for fire protection and their benefits?

There are four main types of check valves for fire protection:

• Alarm check valve
• Swing check valve
• Grooved check valve
• Grooved shotgun riser check valve
• Backflow preventers comprising multiple check valves

An alarm check valve consists of a spring, a valve clapper, and an alarm port. The alarm port can be used to direct water to a water motor alarm or an alarm pressure switch used to alert nearby personnel to the system’s activation or send a signal to a fire alarm control panel.

A swing check valve can act as an alarm check valve for a wet-pipe fire sprinkler system, but only when that valve can sound an alarm.

From the 2022 edition of NFPA 13

16.11.3 Waterflow Detection Devices.

16.11.3.1 Wet Pipe Systems.

The alarm apparatus for a wet pipe system shall consist of a listed alarm check valve or other listed waterflow detection alarm device with the necessary attachments required to give an alarm.

Typically, these alarms are sounded by flow switches, which send a signal to local alarms and/or the fire alarm control panel when water flows through system piping.

Grooved check valves are a type of swing check valve for use in systems that have grooved-connecting pipe ends. Many grooved check valves can be used in a vertical or horizontal orientation, allowing them to be used in various configurations with a fire department connection, bypass connection, gravity pressure tank, or pump discharge connection.

A grooved shotgun riser check valve is similar to a grooved check valve but includes pressure gauges to monitor the supply and system pressure. The shotgun configuration, which uses an electric water flow switch and an alarm bell, is only permitted in situations where a water motor alarm is not required. Shotgun riser check valves offer a more compact and economical alternative to an alarm check valve.

Finally, there are backflow preventers that are explicitly designed to prevent the contamination of water supplies. They use check valves and extra fail-safes to make absolutely sure water flows one way and doesn’t contaminate potable water supplies. You can read more about them in our other blog: “Backflow Preventer vs. Check Valve: What’s the Difference?”

Do check valves require periodic maintenance?

Yes, check valves require periodic inspections and maintenance. For this reason, NFPA 13 warns against burying check valves or positioning them in areas where they will be inaccessible.

From the 2023 Edition of NFPA 25

13.4.2 Check Valves

13.4.2.1 Inspection. Valves shall be inspected internally every 5 years to verify that all of the valve’s components operate correctly.

13.4.2.2 Maintenance. Internal components shall be cleaned, repaired, or replaced as necessary in accordance with the manufacturer’s instructions.

Alarm check valves and system riser check valves require more frequent inspections. Regular inspections help to verify that the clapper functions properly, that the valve seat is in good condition, and that there aren’t any visible signs of corrosion or blockages.

From the 2023 edition of NFPA 25

13.4.1.1* Alarm valves and system riser check valves shall be externally inspected quarterly and shall verify the following:

(1) The gauges indicate normal supply water pressure is being maintained.
(2) The valves and trim are free of physical damage.
(3) All valves are in the appropriate open or closed position.
(4) The retarding chamber or alarm drains are not leaking.
(5) Where applicable, the valve in the connection to the pressure-type contacts or water motor–operated alarm devices are either sealed, locked, or electrically supervised in the open position.

NFPA 25 also requires an inspection of alarm valves’ internal components every five years.

13.4.1.2* Alarm valves and their associated strainers, filters, and restriction orifices shall be inspected internally every 5 years unless tests indicate a greater frequency is necessary.

Maintenance should be performed by following the guidelines set by the manufacturer. Following an inspection, the manufacturer’s guidelines should also be used while returning the system to service.

What’s the best brand of check valve? What should I look for?

Every check valve installed on a fire protection system should be FM-approved and/or UL-listed. Listings certify that a check valve is designed to withstand the conditions it’ll be exposed to while in use. They’re also specifically required by NFPA for check valves on fire sprinkler FDCs and the alarm check valves used with wet-pipe fire sprinkler systems.

From the 2022 edition of NFPA 13

16.11.3 Waterflow Detection Devices.

16.11.3.1 Wet Pipe Systems.

The alarm apparatus for a wet pipe system shall consist of a listed alarm check valve or other listed waterflow detection alarm device with the necessary attachments required to give an alarm.

16.12.6 Valves.

16.12.6.1 A listed check valve shall be installed in each fire department connection and shall be located in an accessible location.

In addition, when you’re purchasing a check valve for fire protection, you should also consider:

• The size and pressure ratings of your fire protection system
• How easy and fast the check valve is to install
• The quality and construction of the valve’s components

QRFS carries UL-listed and FM-approved grooved check valves for pipes ranging from 2 to 6 inches. All of our check valves feature a non-slamming, spring-loaded clapper that forms a water-tight seal against an EPDM synthetic rubber seat. With a durable ductile iron exterior and corrosion-resistant stainless steel clapper, these valves are built to last.

Any of these valves can be installed in a vertical or horizontal orientation. What’s more, each can be used as an alarm check valve with a shotgun riser check valve trim kit, available for every check valve we carry.

When you make a purchase from QRFS, you receive quality products at our competitive pricing. We begin processing your order the moment we receive it so we can provide you with the fastest standard delivery possible, generally reaching you in 2-3 business days.

View our selection of grooved, inline, and swing check valves, plus our inventory of grooved riser check valve trim kits.

Questions about this article or our grooved check valves? Call us at +1 (888) 361-6662 or email support@qrfs.com.

This blog was originally posted by Jason Hugo and Anna Hartenbach at blog.qrfs.com on October 26, 2017, and updated on January 1, 2019. If this article helped you select the right check valve, check us out at Facebook.com/QuickResponseFireSupply or on Twitter @QuickResponseFS.

Water valves are important for controlling the flow of water in a system. One specific type of valve, called a check valve, has a special job: it lets water flow in one direction but stops it from flowing backward. 

 

Check valves play a vital role in plumbing and maintaining water systems. In this article, we will explore the functions of a check valve, explain its importance and provide insight into the different types of check valves available on the market.

 

Av-Tek Valves is dedicated to delivering exceptional products and services that enable you to build high-quality solutions for your community. Browse our catalog or call us at (385) 325-2504 or (801) 637-8541 to learn more about our offerings. You may also visit our blog page for more resources on high-quality valves and their applications.

 

What is a Check Valve?

 

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A check valve, also known as a non-return valve or one-way valve, allows the fluid to flow in only one direction. It is designed to prevent backflow, the reverse flow of fluids in a pipeline, and ensure the unidirectional fluid flow in the piping system.

 

The history of check valves dates back to ancient times when they were used to control water flow in irrigation systems. Over time, check valves have become more sophisticated, and today, they are used in various industries, including oil and gas, chemical, water treatment, and HVAC systems.

 

How Do Check Valves Work?

 

Check valves use a simple mechanism to allow fluid to flow in one direction while preventing backflow. They consist of a valve body, a seat, and a disc or ball that closes the valve opening when fluid flow reverses. When fluid flows in the forward direction, the disc or ball moves away from the seat, allowing the fluid to pass through; meanwhile, when the fluid flow reverses, the disc or ball returns to its seat, blocking the flow and preventing backflow.

 

Types of Check Valves

 

Check valves come in different types, each with its unique design and application, as well as advantages and disadvantages. However, some of the most common types of check valves include:

 

• Ball check valves:

  These valves use a ball that sits on a seat to allow fluid to flow in one direction but prevent backflow when the fluid flows in the opposite direction.

• Inline check valves (Globe-Style Sliding Disc Check Valve):

  These valves are installed within the piping system and use a spring-loaded disc to allow fluid to flow in one direction and prevent backflow when fluid flows in the opposite direction.

• Swing check valves (Butterfly Check Valve) :

  These valves use a swinging disc to allow fluid to flow in one direction and prevent backflow when fluid flows in the opposite direction.

• Lift check valves:

  These valves use a piston or ball to lift off the seat, allowing fluid to flow in one direction but preventing backflow when the fluid flows in the opposite direction.

• Tilting disc check valves:

  These valves use a tilting disc to allow fluid to flow in one direction and prevent backflow when fluid flows in the opposite direction.

• Wafer check valves:

  These valves are installed between flanges and use a spring-loaded disc to allow fluid to flow in one direction and prevent backflow when fluid flows in the opposite direction.

 

What Are the Functions of a Check Valve?

 

Check valves are used in a wide range of applications, including water treatment plants, chemical processing, oil and gas production, food and beverage processing, and HVAC systems. Here are the key functions of a check valve that make it an integral components in many industries:

 

• Prevents Backflow:

  The primary function of a check valve is to prevent the backflow of fluids in a piping system. It ensures that the flow of fluid occurs in one direction only, effectively blocking reverse flow. This is especially important in situations where backflow could cause damage, contamination, or interference with the intended flow direction.

• Protects Equipment and Systems:

  Check valves help safeguard equipment and systems by preventing potential damage caused by reverse flow. They act as a barrier, preventing fluids from flowing back and causing issues such as pump damage, pipe collapse, water hammer, or contamination of sensitive components.

• Maintains Pressure:

  Check valves assist in maintaining optimal pressure levels within a system. By allowing fluid to flow in the desired direction and preventing backflow, they help maintain the desired pressure conditions, ensuring efficient operation of pumps, regulators, and other pressure-sensitive equipment.

• Enhances System Efficiency:

  Check valves contribute to the overall efficiency of a system. By preventing reverse flow, they eliminate the need for additional pumps or mechanisms to counteract backflow, thereby reducing energy consumption and operational costs.

• Minimizes Water Hammer:

  Water hammer

  , characterized by sudden pressure surges or shockwaves in a system, can lead to pipe damage and system failure. Check valves help mitigate water hammer by preventing reverse flow and the subsequent pressure spikes that can occur.

• Allows for System Isolation and Maintenance:

  Check valves provide a means of isolating sections of a system for maintenance or repairs. By closing off the valve, the flow of fluids can be stopped in a specific direction, allowing for safe and efficient maintenance procedures.

 

What To Consider When Selecting a Check Valve

 

Several factors should be considered when selecting a check valve for a specific application. Here are some of the key considerations:

 

Flow Rate and Pressure Drop Considerations

 

One of the primary things to consider when selecting a check valve is the flow rate and pressure drop of the fluid. The type of check valve selected should be able to handle the anticipated flow rate and pressure drop while minimizing head loss.

 

Material Selection Considerations

 

The material of the check valve is also an important factor, as it affects the compatibility of the valve with the fluid being transported. In addition, different materials have different chemical resistance and durability properties, and the selected material should be able to withstand the specific environment and conditions of the application.

 

Temperature and Pressure Limitations

 

Check valves also have specific temperature and pressure limitations that must be considered when selecting a valve. The valve should be able to withstand the maximum temperature and pressure of the fluid without failure or damage.

 

Installation, Maintenance, and Cost Considerations

 

Finally, when choosing a check valve, it’s important to account for the initial purchase cost, assembly expenses, maintenance fees, and ongoing running costs. Cost is typically a significant factor, following quality and functionality. While low purchase prices may seem attractive, they can result in high maintenance and running expenses. Also, a low-cost check valve that fails to perform its intended function can cause serious issues at a pumping station.

 

Check valves must be installed properly to ensure optimal performance and prevent failure. Certain types of check valves may require expensive modifications to the pipeline, which can increase assembly costs. Maintenance and repair expenses also tend to rise as the valve’s complexity increases. In some cases, complex solutions may necessitate the assistance of a professional.

 

Streamline Your System With Av-Tek Valves: The Solution for Efficient Flow Control

 

Check valves play a vital role in maintaining the efficiency and safety of fluid systems. By preventing backflow, protecting equipment, and maintaining pressure, these valves ensure the smooth operation of various industries, including water treatment, chemical processing, oil and gas production, and HVAC systems. Choosing the right check valve for your specific needs requires considering factors such as flow rate, pressure drop, material selection, and maintenance requirements.

 

Remember, a properly selected and well-maintained check valve can significantly enhance the performance and longevity of your fluid systems. Choose Av-Tek Valves and streamline your flow control with confidence, knowing you have a trusted solution for efficient and hassle-free operations.

Av-Tek Valves offers top-quality check valves, including sliding disc check valves and flanged ball check valves. Our products are designed to meet your needs in terms of lead time, quality, and easy maintenance. So if you are looking for a reliable and efficient check valve for your water system, contact us today or call (385) 325-2504 or (801) 637-8541 for more information.

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