Threaded Check Valves Guide
The DFT® SCV® Valve is a versatile all-purpose, non-slam valve that provides reliable, low-maintenance service for a wide range of liquids, steam and gases at various pressure/temperature.
Types of Inline Check Valves from DFT®
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Threaded / Socket Weld Check Valves
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Restrictor Check Valves
Restrictor Check Valves
The Restrictor Check Valve ( RCV) is a spring-assisted, non-slam valve used for applications demanding higher cracking pressures.
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Vacuum Breaker Check Valves
Vacuum Breaker Check Valves
Vacuum Breaker check valves protect against the collapse of pressure vessels, tanks, and rolls while preventing condensate backup when the system is off or the pressure is reduced.
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Sanitary Check Valve
Sanitary Check Valve
The DSV® sanitary check valves meet 3A standard 58-02 and are used in industries with strict hygiene codes. Available in both vertical and horizontal models.
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Wafer Check Valves
Wafer Check Valves
DFT®’s wafer options include ALC®, FBC®, TLW®, WLC®, and WLC® – CAST IRON check valves.
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Flanged Check Valves
Flanged Check Valves
DFT® flanged options include DLC®, Excalibur®, GLC®, GLC® – CAST IRON, and PDC® check valves.
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Butt Weld Check Valves
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Nickel-Aluminum Bronze (NAB) Check Valves
Nickel-Aluminum Bronze (NAB) Check Valves
The DFT® SCV® Valve is a versatile all-purpose, non-slam valve that provides reliable, low-maintenance service for a wide range of liquids, steam and gases at various pressure/temperature
Key Features and Benefits of Our Check Valves
Check valves from DFT® are easy to install and provide a long and reliable service life. Our products are specially designed to prevent water hammer and can be installed in any position. They open at approximately 0.5 Psi differential pressure and fully open at 1.0 Psi differential pressure. Compatible with liquids, gas, and steam, our check valves are available in a wide range of size and style options, with optional soft seats for a bubble-tight shut-off.
Other key features available include:
- Custom Sizing
- MSS SP 126-2000 steel in-line spring-assisted center guided check valves standard
- Pulse-damping design – PDC
- Meeds or exceeds MSS SP-61 leakage requirements
- NACE Standards, MR0175/ISO 15156 or MR0103
- Maintenance and installation guides available
How to Select the Best Type
of Check Valve for Your Application
There are several important considerations involved with check valve selection. To begin the decision-making process, you’ll need to understand your system’s needs. Identify the type of material you’ll be handling, as well as its flow rate, temperature, and pressure. Next, you’ll be ready to select a valve type.
Common Industrial Applications
Check valves from DFT® are used throughout many industries. Some of the most common end uses for our products include:
Building Maintenance
Check valves are installed in HVAC systems as well as in heating and boiler systems to maintain proper flow direction and prevent backflow. They are also used in fire protection systems to ensure one‑way water flow and maintain system readiness.
Chemical Processing
Check valves in the chemical processing industry prevent backflow that could cause contamination, equipment damage, or hazardous reverse flow in systems handling corrosive or high‑pressure fluids. They also protect pumps, compressors, and reactors by closing automatically during flow reversal, maintaining system integrity and safety.
Food and Beverage
Food and dairy processing facilities use check valves to prevent reverse flow and maintain strict sanitary standards. Refrigeration and steam lines also rely on them to stop backflow and reduce the risk of water hammer.
Pharmaceutical
Medications and substances that will be ingested must be processed in a sanitary environment without the potential for reverse flow.
Gas Transmission
Natural gas pipelines require protection against backflow to ensure safe transmission.
Mining
Water management systems and slurry pipelines require water hammer prevention for unwanted water backflow and manage any abrasive materials.
Petroleum production and refining
Check valves are used in pipelines and wellheads regulate the flow of oil and gas, as well as in refinery processes as a safeguard against reverse flow.
Power Generation
Check valves are used within steam and cooling water systems to protect turbines and also within fuel systems to control liquid and gas flow.
Primary Metals
Metal forming hydraulic equipment and the cooling systems within metal manufacturing all require check valves.
Pulp and Paper
Paper pulp processing plants require check valves to maintain proper fluid direction. Water and chemical treatment systems also use these valves to prevent backflow.
Textiles
The textile industry relies on check valves in fluid flow systems during dyeing and finishing processes.
Water treatment
Water treatment facilities and sewage systems need to protect pumps and stop reverse flow of water and to prevent contamination.
DFT®, Your Trusted Check Valve Manufacturer
DFT® has over 70 years of experience manufacturing in-line check valves. Today, our extensive product catalog is used globally by a diverse customer base. Instead of merely meeting line size requirements, our products are developed to meet highly specific needs. If you can’t find an ideal off-the-shelf solution, we offer custom engineering services.
DFT® adheres to the most stringent quality requirements and manufacturing industry best practices. We are ISO 9001:15 certified, 3-A certified, and MSS certified to ensure our products are of the highest possible quality.
Water Hammer Prevention
Find out more on what makes DFT® the check valve to prevent or eliminate water hammer.
Click-to-ExpandOur company is known as the Check Valve Doctor™, and for good reason: We specialize in preventing check valve problems and failures, including those caused by water hammer. DFT®’s in-line, spring-assisted check valves are specially designed to prevent water hammer and reverse flow. And since we offer custom sizing options, we can build check valves to your specific requirements for horizontal or vertical installations in liquid, gas, or steam applications. Even low-flow applications can be custom sized. Proper check valve sizing will optimize a system’s reliability, providing efficient service with maximum protection.
WATER HAMMER is the generation and effect of high-pressure shock waves (transients) in relatively incompressible fluids. Put simply, it is caused by the shock waves that are generated when a liquid is stopped abruptly in a pipe by an object, such as a valve disc. Common symptoms include noise, vibration, and hammering pipe sounds; these effects can then result in flange breakage, equipment damage, ruptured piping, and pipe support damage.
Whenever incompressible fluids exist in a piping system, the potential for water hammer exists. The risk of water hammer is particularly high when the velocity of the fluid is high, there is a large mass of fluid moving, and/or there are large elevation changes within the piping systems.
Since a swing check valve relies on gravity and/or fluid flow to help it close, flow reversal must occur before closure can begin. When the swing check finally does close, it abruptly stops the flow and causes a pressure surge, resulting in shock waves. These shock waves continue until the energy generated from this sudden action dissipates. The figure below displays typical pressure curves after closure of a check valve.
These high-pressure waves act against the piping and the valve, exerting very strong forces. This results in severe stress on the metal and vibrations within the system. If the system is not designed to withstand these high transient forces, the pipe can rupture and other components in the system, such as pumps and valves, may become be damaged.
These problems can be eliminated or greatly minimized by installing a spring-assisted silent check valve. Silent check valves do not rely on gravity or fluid flow for their closure. Instead, as the forward velocity of the fluid slows, the spring assist on the valve starts to close the disc. Due to the spring assist and the relatively short distance the disc must travel, by the time the forward velocity has decreased to zero, the valve disc has reached the seat, and the valve is closed.
With reverse flow eliminated, the forces necessary to produce water hammer on both the upstream and downstream sides of the valves are substantially reduced, as shown on the right side of the figure above.
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