Check Valves

OVERVIEW:  Check valves open with forward flow, and automatically return to close against reverse flow. The main function is to protect mechanical equipment, most notably pumps, where back flow can damage the internal components. Check valves may be grouped according to the way the closure member moves onto the seat. 

The Swing Check Valve has a flat disc that pivots or swings about a hinge pin. They are low cost, and have low head loss characteristics when fully open. But because of the long stroke and inertia of the disc, the traditional swing check valve may slam in vertical pipe installations. These valves are therefore sometimes outfitted with a lever and weight accessory. They can handle liquids with solids such as wastewater.

The most compact swing check valve is the Double Disc Check Valve (aka dual disc). The body is usually a wafer design (fits between two pipe flanges) and it has a hinge pin about which two opposing D-shaped discs rotate. The closure is assisted by a torsion spring which wraps around the hinge pin. It is not used in wastewater containing solids, as spokes that run across the body can collect debris. Advantages are it is small and light, and it has short travel and quick plate closing reducing slamming and make it more suitable for frequent flow reversals. A drawback is a higher resistance to flow because the plates are always in the flow path. Best for clean liquids.

Another type is the center guided lift Silent Check Valve. These in line check valves have spring-loaded discs which move along the pipe axis over a short distance to close automatically in a fraction of a second. Because of their fast closure, these check valves rarely slam and hence have earned the name "silent". They are simple, automatic, and cost effective but can result in higher energy costs in the long run.  They can be economical to produce and reliable in operation. Silent check valves are commonly used in high-rise buildings and high head applications because of their quiet closure. Best for clean liquids.

Quick closure is the key to water hammer prevention, so it is important to consider the speed the check valve will close. And as illustrated here, in addition to its speed of closure, a center guided silent check valve that is almost closed will only have a small amount of reverse flow, so water hammer is not as likely for that reason as well. Conversely, a single disc or double disc swing check valve's proportional flow rate may be greater than than its percentage open, meaning more reverse flow is present.

Check Valve Illustration

                                                                             Check Valve Choices

  • The SIL-DW ductile iron body, center-guided silent check valves with straightener vanes work to eliminate water hammer. The wafer style body design is compact, and mates to 150# and 300# flanges. Buna-N and Viton seats and  stainless steel and aluminum-bronze discs. FM approved. 2" to 10" diameters.

  • The SIL-SW stainless steel body, center-guided silent check valves with straightener vanes work to eliminate water hammer. The wafer style body design is compact, and mates to 150# and 300# flanges.  Stainless steel seats and discs. 2" to 10" diameters.

  • The SIL-DG ductile iron body, center-guided silent check valves with straightening vanes work to eliminate water hammer. The globe style body design allows for minimal pressure loss, and incorporates integral flanges. 150# and 300# classes are offered. Stainless steel and aluminum -bronze seats and discs. FM approved. 2" to 14" diameters.

  • The SIL-CG carbon steel body, center-guided silent check valves with straightening vanes work to eliminate water hammer. The globe style body design allows for minimal pressure loss, and incorporates integral flanges. 150# and 300# classes are offered. Stainless steel seats and discs. 2" to 14" diameters.

  • The SIL-SG stainless steel body, center-guided silent check valves with straightening vanes work to eliminate water hammer. The globe style body design allows for minimal pressure loss, and incorporates integral flanges. 150# and 300# classes are offered. Stainless steel seats and discs. 2" to 14" diameters.

  • The SIL-ST stainless steel body, center-guided silent check valves with thread ends work to eliminate water hammer. Viton seats. 3/8" to 3" diameters.

  • The SIL-BT economical bronze body, center-guided silent check valves with female thread ends work to eliminate water hammer. PTFE seats. Lead free. 1/2" to 2" diameters.

  • The economical SIL-IW cast iron body, center-guided silent check valves work to eliminate water hammer. The wafer style body design is compact, and mates to 125# and 250# flanges. Nickel plated iron or stainless steel seats and stainless steel discs. 2" to 10" diameters.

  • The economical SIL-IG cast iron body, center-guided silent check valves work to eliminate water hammer. The globe style body design allows for minimal pressure loss, and incorporates integral flanges. 125# and 250# classes are offered. Nickel plated iron or stainless steel seats and stainless steel discs. 2.5" to 18" diameters.

  • The SIL-PT PVC In-Line Adjustable Spring Check Valve allows adjustment of the spring for control of back pressure in system, reducing water hammer, and preventing siphoning. Easily adjusts to hold back from 5 to 32 feet of pressure head, 1 psi (2.3 feet of head) for each full turn of the adjustment screw. It is ideal for landscape and irrigation applications, and quickly installs with space saving in-line design. 1/2" - 1" diameters.

  • The DD-DW1 ductile iron body, lead free double disc swing check valves use spring assisted half-discs. The wafer style body design is compact, and it mates to 150# flanges. It is suitable for frequent flow reversals, but not fluids with solids. Buna-N, EPDM, or Viton seats, and aluminum-bronze or stainless steel discs. Lead free and NSF certified for potable water applications. API 594 dimensions. 2" to 24" diameters.

  • The DD-CW carbon steel body, double disc swing check valves use spring assisted half-discs. The wafer style body design is compact, and  is available in 150#, 300#, 600#, and 900# classes. It is suitable for frequent flow reversals, but not fluids with solids. Metal, Buna-N, EPDM, or Viton seats, and aluminum-bronze or stainless steel discs. 2" to 24" diameters.

  • The DD-SW stainless steel body, double disc swing check valves use spring assisted half-discs. The wafer style body design is compact, and  is available in 150#, 300#, 600#, and 900# classes. It is suitable for frequent flow reversals, but not fluids with solids. Metal or Viton seats, and stainless steel discs. 2" to 24" diameters.

  • The DD-CL carbon steel body, double disc swing check valves use spring assisted half-discs. The lug style body design can be used as a block valve. 150# class. It is suitable for frequent flow reversals, but not fluids with solids. Metal, Buna-N, or EPDM seats, and stainless steel discs. 2" to 24" diameters.

  • The economical DD-IW cast iron body, double disc swing check valves use spring assisted half-discs. The wafer style body design is compact, and it mates to 150# flanges. It is suitable for frequent flow reversals, but not fluids with solids. EPDM seats and stainless steel discs. 2" to 24" diameters.

  • The DD-SL stainless steel body, double disc swing check valves use spring assisted half-discs. The lug style body design can be used as a block valve. 150# class. It is suitable for frequent flow reversals, but not fluids with solids. Metal or Viton seats, and stainless steel discs. 2" to 24" diameters.

  • The VCDD-P/H PVC & CPVC Butterfly Check Valves have minimum space requirements and, along with Swing Check Valves, are better for use with fluids containing solids or debris. Its limited travel results in very fast shut off. Flanged, Spigot, Male Thread, Wafter, & Grooved bodies. 2" - 24 diameters.

  • The SF-IG cast iron, full body swing check valves is a proven, durable design that offers a flow path that is unobstructed. 150# class. Buna-N seats, and cast iron discs. 2" to 12" diameters.

  • The SF-IGA cast iron, full body swing check valves is a proven, durable design that offers a flow path that is unobstructed. It comes equipped with a counter weight and lever for additional closure control. 150# class. Buna-N seats, and cast iron discs. 2" to 12" diameters.

  • The SF Industrial Thermoplastic Swing Check Valve is used in many chemical processing applications where a high volume of fluid transfer is required. It is  is available in PVC, CPVC, and Polypropylene. May be fitted with an optional counter balance device. Flanged bodies. 3/4" - 8" diameters.

  • The SS-DW ductile iron swing check valves is an economical design with a flow path that is unobstructed. The wafer style body design is compact and light. Buna-N seats, and stainless stee discs. 2" to 12" diameters.

  • The SS-CW carbon steel swing check valves is an economical design with a flow path that is unobstructed. The wafer style body design is compact and light. Viton seats, and stainless stee discs. 2" to 12" diameters.

  • The SS-SW stainless steel swing check valves is an economical design with a flow path that is unobstructed. The wafer style body design is compact and light. PTFE seats, and stainless stee discs. 2" to 12" diameters.

  • The SP-CW zinc-plated carbon steel swing check valves is a simplified, economical design with a flow path that is unobstructed. The narrow wafer style body design is very compact and flange gaskets are not required due to the built-in, body seal o-rings. Buna-N seats, and stainless stee discs. 2" to 12" diameters.

  • The SP-SW stainless steel swing check valves is a simplified, economical design with a flow path that is unobstructed. The narrow wafer style body design is very compact and flange gaskets are not required due to the built-in, body seal o-rings. PTFE seats, and stainless stee discs. 2" to 12" diameters.

  • The VCYY-P/H Y PVC Gray, PVC Clear & CPVC Y-Check Valves are an angle type valve that automatically stops reverse flow by the dead weight of the disc plug. Y-checks are less affected by turbulent flow and typically have lower shutoff characteristics than ball checks, and also have improved flow characteristics.  In-line clean out. Socket, SR Threaded or Flanged end connections, plus True Union styles available. 1/2" - 4"  diameters.

  • One of the most versatile valve designs available,the BL-P/H  PVC & CPVC True Union Industrial Ball Check Valves provide maximum versatility with fully interchangeable valve cartridges. NSF Certified for potable water service. Low profile design for applications with fluids free from debris and entrained solids. 1-1/2" - 4" diameters.

  • The Model TDV Triple Duty Valve is three products in one, as it takes the place of a balance valve, shut-off valve, and check valve. This spring-loaded valve can be adjusted from full flow to complete shut-off.  A graduated position indicator allows easy adjustment and flow contrtol, and its automatic shut-off helps prevent water hammer.  2" to 20" diameters.

  • The AWWA 7000 Swing Check Valve with its rugged construction and full flow area is the most specified check valve for municipal/industrial water and wastewater applications. It provides significant energy savings over other check valves. Its ductile iron 250 psi rating and fusion bonded epoxy coating place the AWWA Swing in a class above other swing check valves. The available closure options of Lever & Weight, Air Cushion, and Lever & Spring allow the valve to be used effectively in a wide range of pumping system applications.  2" to 48" diameters.

  • The DD PLUS is a versitile double disc swing check valves use spring assisted half-discs for up to 66" sizes. The wafer   ends fit between ANSI 125/150# and Metric PN10/16 flanges. It is suitable for frequent flow reversals, but not fluids with solids. Includes many special features, including lead free and NSF certified for potable water applications. Meets AWWA C518 requirements, UL and FM Approved. 2" to 66" diameters.

  • The SlamBlock Check Valve is excellent in a number of applications including high head, multiple pump and surge tank installations. The SlamBlock achieves rapid closure through a short disc stroke of 35° and use of a closing mechanism to avoid slamming by flow reversal, while at the same time allowing the disc to be stabilized under flow conditions. 2" to 48" diameters.

  • The DD-DG ductile iron body, lead free double disc swing check valves use spring assisted half-discs. The wafer type ends fit between ANSI Class 125/150#, as well as PN10 and PN16 flanges. It is suitable for frequent flow reversals, but not fluids with solids. Lead free and NSF certified for potable water applications. Meets AWWA C518 requirements, UL and FM Approved. 2" to 12" diameters.