Check Valves

A check valve, also known as a one-way inline check valve or non-return check valve, is a device that permits the flow of fluids and gases in only one direction within a pipeline system.

These essential components prevent reverse flow, which can lead to contamination of upstream media or damage to sensitive equipment. Their simple, often automated design relies on flow velocity to open or close, ensuring unidirectional movement without human interaction.

Types of Check Valves

One-Way Check Valve

A one-way inline check valve is typically spring-loaded, allowing fluid flow in a single direction. Inlet pressure overcomes the spring force, lifting a disc or ball off its seat to permit flow to the outlet.

This design effectively prevents backflow. For example, an SMC check valve might be used in systems requiring pneumatic fittings to maintain pressure or prevent reverse airflow.

Double Check Valve

A double check valve assembly features two independent check valves arranged in series, providing enhanced backflow prevention. If one valve fails or jams open, the other can maintain the seal, significantly increasing reliability.

These non-return check valves are commonly used in applications like fire sprinklers and lawn irrigation systems to prevent back-siphonage and back-pressure contamination.

Hydraulic Check Valve

A hydraulic check valve is a simple yet crucial device designed to permit free oil flow in one direction while completely blocking it in the opposite direction. These valves often incorporate a tapered core for superior sealing performance.

They are essential for maintaining pressure in hydraulic circuits, acting as a single-way lock to ensure fluid integrity and prevent pressure loss.

Ball Check Valve

A ball check valve employs a spherical ball that lifts to allow forward flow and seats against an opening to prevent backflow. Its simple design makes it reliable for various applications, including plumbing systems and pumps, where unidirectional flow is essential.

Dual Plate Check Valve

Dual plate check valves feature two semi-circular plates hinged to swing open with forward flow and close against the seat when flow reverses. Their compact design makes them suitable for applications with limited space, such as HVAC systems and fire protection.

Double Door Check Valve

A double door check valve has two hinged doors that open with forward flow and close rapidly to prevent backflow. This design minimises water hammer and is often preferred in large-diameter pipelines, including water treatment plants and pumping stations.

Spring-Assisted Inline Check Valve

A spring-assisted inline check valve uses a spring to help close the valve quickly when flow diminishes, preventing reverse flow and water hammer. This design allows for flexible mounting orientations and is widely used in pneumatic and hydraulic systems for precise control.

Factors to Consider When Choosing a Check Valve

Selecting the right check valve is essential for ensuring efficient and reliable fluid control. Consider these factors to find a valve suitable for your requirements:

• Material: The valve's material must be compatible with the fluid it handles to ensure longevity. For example, opt for a stainless steel check valve if you need high corrosion resistance.
• Size and pressure rating: Ensure the valve's size matches your pipeline diameter and that its pressure rating can safely accommodate your system's operating pressure. Incorrect sizing can lead to inefficiency or failure.
• Installation orientation: Some one-way check valves have specific installation orientations (e.g., horizontal or vertical) for optimal performance. Confirming this ensures proper operation and prevents backflow issues.
• Flow characteristics: Consider how the valve's design impacts fluid flow. Different designs offer varying resistance to flow, which affects system efficiency and pressure drop.

Applications of Check Valves

Check valves are indispensable components across a multitude of industrial applications in NZ, safeguarding systems by ensuring unidirectional fluid and gas flow.

• Water treatment plants: These facilities extensively use check valves to prevent backflow of treated or untreated water, ensuring process integrity and preventing contamination.
• HVAC systems: In heating, ventilation, and air conditioning systems, one-way inline check valves prevent the backflow of refrigerants or condensate, optimising efficiency and preventing system damage.
• Fire protection systems: Crucial for safety, non-return check valves in fire sprinkler and hydrant systems prevent contaminated water from re-entering the main water supply lines.
• Power generation: Check valves are vital in power plants for managing water and steam flow, ensuring efficient turbine operation and preventing reverse flow in cooling systems. Stainless steel check valves are often preferred here.
• Agricultural irrigation systems: These systems employ check valves to maintain prime in pumps and prevent water backflow, ensuring consistent water delivery to crops and efficient resource use.

Your Trusted Check Valve Supplier and Manufacturer in New Zealand

RS New Zealand is a trusted supplier, manufacturer, and distributor of plumbing and pipeline components, offering a comprehensive range of check valves in various types and materials. Our items are sourced from reputable brands in NZ, such as SMC, Parker, Legris, and Georg Fischer, ensuring high-quality options for every need.

Beyond specialised valves, we also offer a wide array of other mechanical components like hose pipes and water pressure regulators, catering to diverse project needs.

Browse our user-friendly online site to find the product that you need and have it shipped to you with our convenient delivery options. With flexible options available, we ensure that you receive your items when you need them. For more details on delivery times and fees, check out our delivery information page.