Category Archive: Check Valves
Maintenance and Replacement Blog Series: Preventing Water Hammer with SCV® Check Valves
For more than 70 years, DFT® Inc. has focused on manufacturing dependable and high-quality check valves across all industries. We have a long history of solving valve problems and preventing failures, exemplified by our line of SCV® Check Valves.
Specially designed for tight shutoff, high cycling, and system protection from the effects of water hammer, these valves are relied on for a variety of liquid, gas, and steam applications. Equipped with corrosion-resistant features, SCV Valves are an economical and consistently dependable option.
Designed for Optimal Water Hammer Resistance
Water hammer is a persistent and potentially highly damaging problem that is found in all types of piping systems. It occurs when moving fluids are forced to suddenly stop; once stopped, the fluid’s momentum creates a pressure wave that flows throughout the closed pipe system.
The resulting pressure spikes can cause significant damage to domestic and industrial piping systems. However, this damaging phenomenon can be prevented using specialty products, such as SCV® Check Valves. For more information, download our water hammer eBook.
Advantages and Features of SCV® Check Valves
With simple yet rugged construction, SCV® Check Valves offer a full array of features:
- Protection from Water Hammer — This valve model was specifically designed to protect all types of applications from water hammer. It features a non-slam, spring-assisted design that provides a tight shutoff.
- Simple Design — The rugged valve construction consists of a body, seat, spring, edge-guided disc, and body seal, which is engineered to handle at least a million cycles.
- Best Quality Materials — Built to withstand the harshest industrial environments, SCV® Check Valves are constructed from the finest quality materials, including:
- ASTM A240 316 for the disc
- Inconel® X-7650 for the spring
- ASTM A351 CF8M for the seat and body
- Zelon® O-Ring for the seal, with optional seal-welded body joint that can handle temperatures up to 700°F
- Soft Seat, NPT, or Socket Weld Ends are available
- Options include 316SS springs, body seal weld, soft seat, Alloy 20 or Hastelloy C body & seat (ASME 300)
- All Sizes Available — SCV® Check Valves are available in sizes ranging from 1/3” to 3”
- Built to Handle Most Media — The valves handle 750 cold working pressure (CWP) and 3600 psi, providing tight shut off capabilities for gas, liquid, or steam
Choose SCV® Check Valves for Your Applications
Easy-maintenance check valves from DFT® are available for installation in both vertical and horizontal configurations. Customers in a wide range of industries, from mining and steam transmission to primary metals and power generation, rely on our check valves for many of their applications.
To learn more about the features of SCV® Check Valves, download our SCV® cut sheet. Additional information is available on our Threaded In-Line Check Valves catalog page or by contacting the DFT® team directly.
Maintenance & Replacement Valves Blog Series:
Vacuum Breakers and Their Applications
Valves play an integral part in many applications performed by anyone from a manufacturer to an engineer to a construction manager. The basic function of a valve is to control both the flow and pressure within a process or system. The functions of a valve include:
- Regulating a flow or process pressure
- Relieving a system of pressure
- Stopping or starting a flow
- Increasing or reducing a flow
- Controlling the flow’s direction
Keeping this in mind, a Vacuum Breaker Check Valve provides effective protection against collapse of pressure vessels, tanks and piping. This particular valve prevents condensate “back-up” when equipment is shut down or inlet steam is reduced by modulating control valves. Within a piping system, DFT® Vacuum Breakers can perform helpful tasks, such as:
- Breaking a siphon
- Preventing pipe collapse during transient pressure drops
- Providing additional air on downstream side of check valves to help prevent water hammer
This variation of a check valve, or Vacuum Breaker, features a spring-assisted silent closure. If there is no pressure on the valve, the spring pushes the disc into a closed position. Other features include:
- 1” to 4” size range (MNPT)
- 450 to 6000 CWP
- Threaded O.D. with unthreaded inlet bore
- Stainless steel construction
- Horizontal or vertical installation
- Tight shutoff – lapped disc and seat
- Inconel X-750 Spring
- soft seat options
The wide variety of DFT® Vacuum Breakers makes it easy to find and install the one that’s correct for any application. Beyond their use in building water systems, they can be used in anything from chemical processing to power generation to pharmaceutical applications.
With so many applications requiring a strict no-backflow function, we’ve compiled a list of codes and standards, as well as industry applications into a downloadable catalog. Select the button below to download our free eBook, Vacuum Breaker Check Valves: Your Defense Against Pipe Collapse & Pressure Vessel Damage.
10 Things Engineers & Maintenance Managers Should Know About Check Valves
Check valves serve a wide variety of purposes and services. Understanding how they work is essential to accessing the range of benefits they offer. We all want to purchase check valves that are not only of the highest quality, but offer long-lasting durability and sustainability. Finding the best valve for your project requires research and a clear understanding of the way the valves work and how they will impact your application. To ensure that your valves run smoothly from start to finish, there are key facts about check valves that all engineers and maintenance managers must know.
Below is DFT’s list of the top ten things to keep in mind when purchasing and implementing check valves.
- Check Valves are an essential element in the design of an efficient pumping system
- Check Valves should be sized for their application and flow, not based just on pipe diameter
- Water Hammer is a direct result of a pressure surge or wave caused when a fluid (usually a liquid or slurry ) in motion is forced to stop or change direction suddenly
- Water Hammer can be significantly reduced with the correct choice of Check Valve
- An undersized valve will cause high pressure losses and create excessive noise and vibration
- An oversized valve can lead to premature wear and failure of the valves internal components
- Properly sized check valves can dramatically add to the life of the valves as well as longevity of pumps and other related components
- An energy efficient check valve is a properly sized check valve in a pump fluid flow system that allows the required flow, while minimizing energy consumption
- Low flow application check valves should be sized so the valve is fully open based on maximum flow
- Metal sealing surfaces generally will allow some leakage while elastomers (soft seats) such as Buna-N and Viton provide bubble-tight shutoff (zero leakage)
When used properly and for the appropriate projects, check valves can offer consumers a wide range of useful benefits. Understanding their capabilities, then, proves an essential part of utilizing them toward the success of your system. To find out other key considerations when designing fluid or Gas flow Systems, download our Design for Flexibility eBook.
At DFT Valves, we’re committed to providing you with exemplary valves for a wide range of systems and services, if you have questions, please contact us today.
DFT Releases Efficient New Axial-Flow Check Valve
DFT Inc., an industry leader in the manufacturing of check valves for more than 70 years, proudly announces the release of its new BNC™ Check Valve, a nozzle-style, axial-flow check valve specifically designed to excel in high-pressure applications.
Many natural gas companies and other industries are now placing their pipelines below ground and are looking for a one-piece valve they can weld in and bury. The BNC™ Check Valve answers that demand with a precision nozzle-style valve that uses axial-flow technology to eliminate turbulence and prevent erosion and vibration. This design reduces downtime and maintenance costs and boosts capacity and accuracy.
Additionally, this valve provides a critical service to the power industry because the valve’s one piece body eliminates leak paths, while providing tight shut off.
This valve is a spring-assisted, center-guided, non-slam check valve. It has an in-line globe-style body with butt weld ends, with the seat integral to the valve body.
The one-piece valve is designed for long life and a no maintenance required design.
The design meets ASME B16.34, and its testing meets MSS SP-61 and API 598 (shell and seat). The valve is available in 10″ to 24″ line sizes, and it is constructed of A216-grade WCB carbon steel and other alloys per ASME 16.34 by request.
Trim materials are carbon steel and stainless steel with a hard-faced seat and disc. The valve can be installed either horizontally or vertically and is compatible with steam, water, and gaseous media. Custom sizing for the BNC™ Check Valve is available.
ABOUT DFT INC.
DFT Inc. manufactures severe service control valves and in-line check valves in its Exton, Pennsylvania, facility. DFT takes pride in working closely with end users to solve problems. The results are valves that provide superior performance, long service life, and low maintenance costs.
Meet the PDC Valve, DFT’s Unique Check Valve
Industry professionals responsible for proper fluid and gas flow are well aware of the importance of check valves. Since many check valves operate automatically and are not under constant human control, choosing the right type of valve is critical.
Every application demands a unique valve; this is particularly true when referring to the discharge side of reciprocating air or gas compressors. Reciprocating compressors, also known as piston compressors, are used in a variety of industrial applications, including:
- Oil refineries
- Gas pipelines
- Chemical and natural gas processing plants
- Refrigeration plants
- Building maintenance
- Mining
- Power generation
- Primary metals
- Pulp & paper
- Textiles
Reciprocating compressors produce high levels of pressure in order to move gases, so any check valve utilized in this process must be extremely durable and reliable.
At DFT, our team designs, manufactures, and distributes an assortment of check valves to suit even the harshest applications. In order to handle the demands of discharging reciprocating compressors, we have created the unique DFT® Model PDC® Silent Check Valve.
The PDC® valve is a nozzle-style, spring-loaded check valve that allows gases to flow in only one direction. The PDC® valve offers users a variety of benefits; perhaps its most significant feature is its unique pulse damping chamber. The valve’s pulse damping chamber helps maintain the disc in the open position during momentary reductions in flow, which are directly associated with each cycle of a reciprocating compressor. Pulse damping will also protect against costly premature seat wear.
No matter your company’s needs, DFT offers a PDC® Silent Check Valve to fit any application. Our selection of 59 different PDC® Silent Check Valves includes:
- Different ASME classes (150 RF, 300 RF, 600 RF, 900 RF, 1500 RF)
- Various sizes (2”-DN 50; 3”-DN 80; 4”-DN 100; 6”-DN 150; 8”-DN 200; 10”-DN 250; 12”-DN 300)
- Dimension A (9.5-44.5”/ 241-1130mm)*
- Dimension B (6”-26.5”/152mm-673mm)*
- Cracking Pressures of 0.35 psig/0.024 bar-0.82 psig/0.057 bar
- A216 Grade WCB, A352 LCC, A351 CF8M body materials
*Larger sizes available via factory consultation.
The PDC Silent Check Valve meets several industry standards, including ASME B16.10 (for face-to-face dimensions).
If you need to rely on reciprocating compressors, then the DFT® Model PDC® Silent Check Valve might be the ideal choice for you. To learn more about this one-of-a-kind product, visit our resource library or contact a DFT representative today.
