Product Description

Check Valve Product Introduction & Technical Specifications

1. Product Introduction

A check valve (also known as non-return valve, one-way valve, or reflux valve) is an automatic valve that requires no external power. It opens and closes by relying on the pressure difference of the medium itself.

Its core function is to prevent backflow of pipeline media, protect key equipment such as pumps, compressors and boilers, and suppress the impact of water hammer on the system.

Working principle:

 When the medium flows forward, the medium pressure pushes the valve disc open.

 When backflow occurs, the combined action of the medium pressure and the disc weight / spring force presses the disc against the seat to achieve sealing.

2. Technical Specifications

 Nominal Diameter (DN): DN15 - DN2000. Small sizes (DN15-DN50) commonly use threaded or socket weld connections; large sizes (DN100) use flanged or wafer connections.

 Nominal Pressure (PN/Class): PN1.0, PN1.6, PN2.5, PN4.0, PN10, PN16; Class 150, 300, 600. Carbon steel standard rating: PN16 / Class 300; stainless steel can reach PN40 / Class 600.

 Working Temperature: -29 to +425 (carbon steel); -196 to +550 (stainless steel / alloy). Temperature range depends on material and seals: PTFE seal 260; metal seal up to 550.

 Applicable Media: Water, steam, oil products, natural gas, acid/alkali salt solutions, food-grade media, etc. Material selection is determined by medium corrosiveness, e.g., 316L for hydrochloric acid, duplex steel for seawater.

 Connection Type: Flanged, threaded, wafer, welded (butt weld / socket weld). Wafer type for limited installation space; welded type for high temperature and high pressure applications.

3. Main Component Materials

Body / Bonnet

 Cast iron / Ductile iron: Low cost, suitable for low pressure and normal temperature (PN1.6MPa, 120), such as water treatment and municipal pipelines.

 Carbon steel (WCB): Suitable for medium-high pressure and medium temperature (425), such as steam and hot oil pipelines.

 Stainless steel (304/316/316L): Corrosion-resistant, suitable for acid/alkali, seawater, food and pharmaceutical applications; 316L offers better corrosion resistance.

 Alloy steel (Cr-Mo): High temperature and high pressure resistance (550, PN40+), used in power stations and refinery units.

Internal Parts (Disc, Seat, Stem)

 Disc / Seat: 304/316, with hardfacing Stellite alloy to improve wear resistance.

 Stem: 2Cr13/316, with surface quenching / nitriding treatment to prevent galling.

 Spring: Stainless steel (302/316), corrosion-resistant and fatigue-resistant.

Seals

 Metal seal: Suitable for high temperature and high pressure (400).

 Elastomer seal (PTFE, EPDM, NBR): Suitable for normal temperature and low pressure, with excellent sealing performance and low noise operation.

4. Product Classification (By Structure)

1. 

Lift Check Valve

2. 

o Horizontal lift: Installed horizontally, the disc lifts vertically along the guide rail, with good sealing performance and slightly higher flow resistance. Suitable for small to medium diameter, high pressure and clean media (e.g., DN15-DN200, PN16-PN40).

o Vertical lift: Installed vertically (medium flows upward from below), commonly used in boiler feedwater and condensate pipelines to avoid space limitations of horizontal installation.

3. 

Swing Check Valve

4. 

o Single disc: Simple structure, suitable for small diameters (DN50-DN300) and general working conditions.

o Double disc: Quick closing, low water hammer impact, suitable for medium diameters (DN200-DN600).

o Multi-disc: Extremely low flow resistance, suitable for large diameter pipelines (DN600), such as long-distance pipelines and large pump station outlets.

5. 

Butterfly / Wafer Check Valve

6. 

o Butterfly type: Disc is disc-shaped, rotating around the valve shaft, with very low flow resistance and light weight. Suitable for low pressure and large diameters (PN1.6MPa, DN300+).

o Wafer type: Installed between two flanges without independent flanges, requiring compact installation space. Commonly used in water supply and drainage, air conditioning circulation systems.

7. 

Spring-loaded Check Valve (Silent / Compact Type)

8. 

o Closed with the help of spring force, not limited by installation direction, can be installed at any angle. Suitable for narrow spaces and applications requiring water hammer prevention (e.g., building risers, pump outlets).

5. Product Features

1. Automatic operation, no manual / power required: Pure mechanical structure, driven by medium pressure, no energy consumption and low failure rate.

2. Equipment protection and water hammer suppression: Prevents backflow from damaging pumps/compressors; some types (double disc, spring-loaded) can significantly reduce water hammer impact.

3. Diversified adaptation: Multiple structures and complete material options, covering almost all pipeline working conditions from civil low pressure to industrial high pressure, high temperature and strong corrosion.

4. Flexible installation: Swing type can be installed horizontally or vertically (vertical installation requires medium to flow upward from below); spring-loaded type can be installed at any angle; wafer type saves installation space.