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 check valves
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.
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.
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.
General Industrial Check Valves
The VCP-B521 is a bronze union bonnet check valve that has stainless steel trim traditionally for steam service.
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.