Check Valves, Swing, Wafer, Venturi Non slam check for Petroleum, waterworks, Chemical stainless steel brass steel and PFA lined.
Check Valves also referred to as non-return or reflux valves operate automatically. They allow flow in one direction only. At the start of the industrial era stopping and starting flows was more important than flow reversal issues. It wasn’t really until early 1900s that they became concerned about back flow or flow reversal in pipelines and processes. It is always best to select the correct type and size of check valve to the application.
Types of check valves
The range is quite diverse such as inline in the smaller instrumentation range, in the larger sizes say from 15nb and above there are poppet checks, lift checks, swing checks, disc checks, twin flap checks, silent checks, nozzle checks, ball checks, 3 piece checks, checks with dashpots, checks with counter levers and weights, metal seated, soft seated, and in materials ranging from plastic, brass, iron, steel and stainless.
They are available with swage fitting ends, socket end, threaded, buttweld, flanged and wafer styles. Pressure ranges from 125psi to over 6000psi. Each type in its various materials and design has its application and we do them all right up to 3600nb size. For further reference refer to our Industry Sections Waterworks or Petrochemical.
MARINE Valves are specific for that industry manufactured from ASTM B62 and ASTM B148 (Bronze and NI Bronze) materials. Naval Valves.
Overview
Specialists Non Slam or Axial Nozzle check valves
NOW AVAILABLE IN MULTI-FLANGE WAFER DESIGN
Traditional Non slam or axial check valves are specialist engineered units used in the likes of compressor or pump station applications. They are individually sized to suit each pipework design conditions.
Why use a Nozzle check valve? There are a few reasons one being economics. ENERGY EFFICIENCY! Pressure losses / pumping / operating costs can be far more than the cost of the wrong valve selection. A Nozzle check can save %50 of the pumping cost compared to using a conventional check valve. Nozzle checks due to their flow dynamics minimize water hammer hence the generic name non-slam checks. Nozzle checks also far outlast (sometimes 10 times) a conventional check valve due to the nature of their operation from less wear. The new Wafer design adds a whole heap of additional benefits and makes them more economical thus attractive to desalination or HVAC applications.
The wafer design valve reduces installation costs with time, weight, materials savings. One size valve per the size fits the whole range of most common flange types making supply logistics easy for sites. Standard bodies are 316L but Super Duplex, Alloy 600 etc. are options. These are in the lower pressure classes up to PN40 or ANSI 300 ideal for desalination, HVAC or offshore work.
Wafer check valves (compact space saving check valves fitting between flanges)
Dual plate or Twinfold wafer check valves are economical and offer much easier installation compared to the long body flanged swing check valves. They are also much less likely to cause water hammer due to their method of operation. Available in various body / plate materials with options of metal or soft seat. VCS carry a variety of sizes and pressure ratings in both wafer and lugged versions.
Wafer dual plate check cracking pressures are lower than normal swing checks. Typically a 200nb (8″) wafer valve will have a cracking pressure of 30kpa which in most instances is acceptable. However we can achieve cracking pressures as low as 2kpa with alternative spring arrangements using the 200nb size as an example. If you have special flow requirements or cracking pressures and need valves selected accordingly, we can assist.
The Twinfold WCV-SE12HMP dual plate Class 125 wafer check has a cast Iron body, stainless steel plates and Buna N seat (Viton optional) that fits in between matching flanges is the most common of all the wafer checks. Found in most HVAC plumbing and irrigation sectors for the last 40 years. It is an engineered valve different from some of the competition throw away types. On pumps etc the SE12HMP is the preferred valve for long-livity and quiet operation.
The steel body versions below are predominantly used in the oil and gas markets which are metal seated or viton seated to suit the service.
Another version of the WAFER CHECK style is the Disc Check where a single disc is supported in the flow center and operates with the aid of a single central spring. These are Stainless body and trim metal seated from DN15 to DN100 size and are popular in steam industry. They are a universal check meaning the one valve fits between AS ANSI and DIN PN40 flanges. There are 2 options available. The “universal” is an inexpensive version ii fits between the flanges as required however the trade off is the limited seating surface between the flanges requiring care during installation.
The ideal valve is a true multi-flange unit with full seating surface areas in compliance with DIN standards covering AS / BS, DIN 16/DIN25/ DIN40 along with ANSI 150 and ANSI 300. If your application is in the Oil and Gas or Power Generation sectors where upmarket products are a necessity this is the one to choose VDC-S304M.
Updated Data VDC-S304M to be uploaded Dec 2025 or call our sales office for further info.
General Industrial Check Valves
The VCP-B521 is a bronze union bonnet check valve that has stainless steel trim traditionally for steam service.
Forged steel class 800 check valves (Piston check, Ball check and Swing check) once only in NPT and Socket weld are now also available in BSP connections.
Oilfield Valves
The oilfield range covers small bore 3000psi swing check valves (and 3000psi Ball valves) from 1″ to 4″ (DN25 to DN100) primarily in Cast steel materials. End connections can be BSP or NPT with the majority being NPT. These valves have a VITON soft seal back up seating ring
Check Valves for pneumatics or compressed air lines
Poppet Check valves for compressed air lines are not standard check valves they are built to take the constant vibrations / pulsations that can be common in these installations. The most popular is the spring assisted in line version VCP-A8 which are stocked from 6mm through to 25mm and available right through to 50mm. These have an aluminium body with NBR sealing, typically they are good for over 150,000 operations. Another version is the VCP VA8 which is an angle vent type.
Chemical Service Valves
On aggressive chemicals PFA or FEP lined valves and pipework are well used in industry particularly on acid service. The PFA is dovetailed into the valve bodies ensuring the valves operation even in vacuum applications. The AZ Valves Globus valve is a fully lined / coated ball check valve. The valve is available in PN 16 PN40 and ASA 150 flanging. An extended body version also allows for a sight glass to view / confirm flows and operation.
Slurry – Chemical – Sewage Service Check Valve
For light slurries, chemical mixes, sewage applications a full flow uninterrupted flow path is ideal minimizing any turbulences within the pipeline is an ideal requirement. Rubber lining also gives resilience from abrasion and corrosion. Being full flow it can also allow for pigging of the lines in certain instances. The VNX series valve is now unique in the market as the original Saunders NX series ceased production some years ago. The VNX operates on the same principal as the original NX valves that were tried and tested for decades in these applications. Also ask about spare replacement discs (which is the only spare wear component). If you are using rubber lined diaphragm valves this is the perfect partner check valve.
NOTE AS OF OCTOBER 2024 THE VNX CHECK VALVE SERIES SIZE RANGE IS EXTENDED TO DN300 (12″)
Some water and sewage systems allow for a BALL CHECK to be used. This style of valve operates with a rubber coated ball that rolls back and forth in and out of the flow path. The round ball gives a varied seating surface when in contact with the metal seat. . Sizes are from 50mm through to 400mm.