Check Valve

Introduction to Check Valves

In piping systems, check valves are used to control flow direction and protect downstream equipment. They allow fluid to flow in a designated direction and automatically close when reverse flow occurs. This self-operating mechanism makes check valves widely used in water supply and drainage, HVAC, fire protection, and various industrial applications.

Depending on operating conditions, check valves are designed in different types to suit applications ranging from low-pressure systems to continuously operating pipelines. Key technical requirements include tight sealing, fast response, and low pressure drop to ensure overall system efficiency and stability.

Among check valve manufacturers, Watts products are recognized for their reliability and optimized design. The valves are engineered for effective shut-off and quick response to pressure changes, preventing backflow efficiently. High-quality materials combined with precise manufacturing help reduce pressure loss and maintain stable performance in demanding, continuous-operation systems.

Operating Principle of Check Valve

To effectively prevent backflow, a check valve operates based on pressure differential within the pipeline. Changes in pressure conditions automatically trigger the valve’s internal mechanism without any external control. The working principle can be described as follows:

• When the inlet pressure is higher than the outlet pressure: The fluid force acts on the disc or flap, pushing it open and allowing flow in the designed direction.
• When pressure equalizes, or flow rate decreases to near zero: The disc moves toward a neutral or near-closed position, helping reduce flow fluctuations and minimize vibration in the pipeline.
• When backflow occurs: Increased downstream pressure forces the disc to close tightly, preventing reverse flow and protecting pumps, equipment, and the upstream system.

Watts Check Valve Product Line

Watts offers a wide range of check valves with different designs and specifications to meet diverse requirements in water systems, HVAC, fire protection, and industrial applications. In Vietnam, Toan Cau supplies a full portfolio of genuine Watts check valve models, suitable for various installation conditions and pressure ranges. Below are some of the key product lines currently distributed by Toan Cau.

Series R5001/R5001N

The R5001/R5001N is a silent check valve from Watts, designed to prevent backflow and protect domestic water supply systems. Its optimized internal mechanism enables smooth operation, reduces noise, and minimizes water hammer in the pipeline. The valve can be installed in various orientations while maintaining reliable sealing performance. Constructed from high-quality brass, it ensures durability and safe operation in potable water systems.

Below are the key technical specifications of this series:

• Valve size: DN15 – DN50
• Body material: Brass
• Nominal pressure: PN16
• Temperature range: -20°C to 120°C
• Test standard: BS EN 12266-1
• Connection standards: BSPT to ISO 7-1, NPT to ASME B1.20.1 / MSS SP-80
• Working medium: Water
• Certification: ACS

Series 402AF

The 402AF is a flanged silent check valve from Watts, designed to prevent backflow and reduce water hammer in piping systems. The valve operates reliably in both horizontal and vertical installations, making it suitable for water supply, drainage, HVAC systems, and pump applications in high-rise buildings. Its closing mechanism, combining disc weight and spring force, ensures fast shut-off, minimizes noise, and maintains reliable performance during continuous operation.

Below are the key technical specifications of this series:

• Valve size: DN50 – DN600
• Body material: Ductile iron
• Nominal pressure: PN16
• Temperature range: 0°C to 80°C
• Test standard: GB/T 13927-2008
• Connection standard: GB/T 17241.6-2008
• Working medium: Water

Series W-H41X-25C

The W-H41X-25C is a silent check valve from Watts, designed to prevent backflow in water supply and water treatment systems. The valve operates fully automatically based on flow direction, opening when flow is present and closing tightly when reverse flow occurs. Its simple construction helps reduce manufacturing costs, while the smooth closing mechanism minimizes noise during operation.

Below are the key technical specifications of this valve:

• Valve size: DN50 – DN600
• Body material: Carbon steel with spray paint
• Nominal pressure: PN25
• Temperature range: 0°C to 80°C
• Test standard: GB/T 13927-2008
• Connection standard: GB/T 17241.6
• Working medium: Water

Series W-H77X-16Q

The W-H77X-16Q is a wafer-type double door check valve from Watts, designed to prevent backflow in water supply and water treatment systems. The valve operates automatically using fluid flow combined with a torsion spring mechanism, enabling quick closing, reducing water hammer, and minimizing pressure loss. Its compact and lightweight wafer design allows flexible installation between flanges, suitable for both horizontal and vertical pipelines, especially in systems with limited installation space.

Below are the key technical specifications of the W-H77X-16Q:

• Valve size: DN50 – DN600
• Body material: Gray cast iron coated with epoxy
• Nominal pressure: PN16
• Temperature range: -10°C to 120°C
• Connection standard: EN 1092-2
• Connection type: Wafer
• Working medium: Water

Series W-H44X-16Q

The W-H44X-16Q is a swing check valve from Watts, designed for systems requiring stable flow and low pressure loss. The valve disc fully opens in the direction of flow, minimizing resistance, and closes quickly when reverse flow occurs to protect the system. A key feature of this series is the EPDM-coated disc, which enhances sealing performance, reduces wear, and extends service life during operation. With a robust structure and epoxy-coated body for corrosion resistance, the W-H44X-16Q is suitable for water infrastructure and industrial applications requiring high durability.

Below are the key technical specifications of this series:

• Valve size: DN50 – DN600
• Body material: Ductile iron coated with epoxy
• Nominal pressure: PN16
• Temperature range: 0°C to 80°C
• Test standard: GB/T 13927-2008
• Working medium: Water

Series W-HQ41X-16Q

The W-HQ41X-16Q is a ball check valve from Watts, designed to prevent backflow through the automatic movement of a spherical valve ball. When the fluid flows in the correct direction, the ball moves freely to allow stable flow passage. When reverse flow occurs, the ball quickly returns to the seat and seals tightly, minimizing leakage. A key advantage of this series is its simple construction, with a ball-type disc that provides reliable sealing performance and high operational dependability, especially in continuous-duty industrial systems.

Below are the key technical specifications of this series:

• Valve size: DN50 – DN400
• Body material: Ductile iron coated with epoxy
• Nominal pressure: PN16
• Temperature range: 0°C to 80°C
• Test standard: GB/T 13927-2008
• Connection standard: GB/T 17241.6
• Working medium: Water

Series W-H44W-16P

The W-H44W-16P series is a stainless steel flanged swing check valve from Watts, designed to prevent backflow and protect pumps as well as drive motors from reverse rotation. A key feature of this series is its full stainless steel construction, allowing stable operation in water supply and drainage systems with high cleanliness and water quality requirements. The disc closes quickly, while the streamlined flow path helps reduce pressure loss and maintain long-term operating efficiency with high reliability.

Below are the key technical specifications of the W-H44W-16P:

• Valve size: DN50 – DN200
• Body material: Stainless steel
• Nominal pressure: PN16
• Temperature range: -29°C to 150°C
• Test standard: GB/T 13927-2008
• Connection standard: JB/T 79.1-1994
• Connection type: Flanged
• Working medium: Water

Series B5002/B5002N

The B5002/B5002N is a bronze check valve from Watts, designed to prevent backflow and protect systems in potable water applications. This series stands out for its durable bronze construction, compact size, and low pressure loss, making it suitable for residential and technical piping systems with limited installation space. The product offers high durability and safety, and is approved for potable water use under WRAS standards.

Below are the key technical specifications of the B5002/B5002N series:

• Valve size: DN15 – DN50
• Body material: Bronze CC491K
• Nominal pressure: PN20
• Temperature range: 0°C to 80°C
• Design standard: GB/T 8464
• Connection standard: BSPT thread; NPT thread available for B5002N version
• Test standard: BS 6755
• Connection type: Threaded
• Working media: Water, oil, steam
• Certification: WRAS

Series W-H44T-16Q

The W-H44T-16Q is a swing check valve from Watts, designed to prevent backflow and protect systems in plumbing, HVAC, irrigation, commercial, and industrial applications. The disc fully opens in the direction of flow, resulting in low pressure loss, and closes tightly when reverse flow occurs, ensuring safe operation. A key feature of the W-H44T-16Q is its robust ductile iron construction with internal and external epoxy coating, providing corrosion resistance and long service life in demanding environments.

Below are the key technical specifications of the W-H44T-16Q:

• Valve size: DN50 – DN300
• Body material: Ductile iron (16Q)
• Nominal pressure: PN16
• Temperature range: -15°C to 120°C
• Design standard: BS 5153
• Connection standard: PN16 to EN 1092-2
• Connection type: Flanged
• Working medium: Water

Series W-H44T-125Q

The W-H44T-125Q is a swing check valve from Watts, designed for piping systems using ANSI flanges. The disc fully opens in the direction of flow to minimize pressure loss, and closes tightly when reverse flow occurs to protect equipment and pipelines. A key advantage of the W-H44T-125Q is that it is combined with a robust ductile iron body and internal/external liquid epoxy painted for enhanced durability in residential and industrial applications.

Below are the key technical specifications of the W-H44T-125Q:

• Valve size: DN50 – DN300
• Body material: Ductile iron
• Nominal pressure: CL125
• Temperature range: -15°C to 120°C
• Design standard: MSS SP-71
• Connection standard: CL125 to ANSI B16.1
• Connection type: Flanged
• Working media: Water, oil, gas

Series W-DPC01

The W-DPC01 is a dual plate wafer check valve from Watts, designed to protect pumps and critical equipment from backflow during operation. Its slim and compact body is installed directly between two flanges, allowing flexible installation in horizontal pipelines or vertical upward-flow pipelines. The spring-assisted dual plate mechanism provides rapid closing to reduce water hammer while maintaining reliable sealing performance in HVAC systems and other applications handling fluids compatible with the valve materials.

Below are the key technical specifications of the W-DPC01 series:

• Valve size: DN50 – DN300
• Body material: Cast iron
• Nominal pressure: 1600 kPa
• Temperature range: -10°C to 90°C
• Connection type: Wafer construction for installation between Table E flanges
• Working media: Non-corrosive liquids

Series W5000

The W5000 is a stainless steel check valve from Watts, designed to protect against medium backflow. A key feature of the W5000 is the option of welding or clamp connections, providing flexible installation and convenient maintenance or pipeline cleaning. Its compact structure, low flow resistance, and stable operation make this series suitable for systems requiring high cleanliness and dependable performance.

Below are the key technical specifications of the W5000 series:

• Valve size: DN15 – DN100
• Body material: Stainless steel
• Nominal pressure: PN10
• Temperature range: -10°C to 100°C
• Connection standards:
  • Welding: DIN 11850 / ISO 2037
  • Clamp: DIN 32676 / ISO 2852
• Test standard: GB/T 13927
• Suitable media: Water, ≤ 50% ethylene glycol

Toan Cau – Official Distributor of Watts Water Technologies in Vietnam

Watts check valves are trusted for reliable quality, durable construction, and stable performance in water systems, HVAC, and industrial applications. In Vietnam, Toan Cau is the official distributor of Watts check valves, supplying genuine products with clear technical documentation. With over 18 years of experience, Toan Cau has supported investors, engineers, and contractors in many technical projects.

Besides check valves, Toan Cau also supplies other Watts products such as ball valves, butterfly valves, globe valves, control valves, and safety valves… helping customers complete integrated system solutions. With strong technical support and stable stock availability, Toan Cau ensures confidence throughout project implementation. For consultation or quotation, please contact hotline 0911 771 551.