CHECK VALVES: PURPOSE & FUNCTIONALITY
Check valves are self-automated valves that allow the flow of gases and liquids to move one way, preventing any reverse or backward flow of material inside a pipeline. Its versatile nature allows them to be installed vertically or horizontally, without human interaction, and reliant on the flow to open and close. The internal disc inside the check valve allows the flow to pass forward, which opens the valve. Then, dependent on its design, the disc starts to close the valve as the forwarding flow decreases or reverses.
CHECK VALVES FEATURES & BENEFITS:
- Available in a wide range of sizes
- Prevents backflow
- Lower maintenance costs
- Increase energy savings
- Maintains pressure
- Serves as a backup system
- Can be used horizontally and vertically
- Flexible when dealing with a variable flow
- Reduce the chance of sudden valve failure, as they eliminate chatter vibration
CHECK VALVE APPLICATIONS
Check valves are primarily used for one of four reasons in a wide variety of applications:
- To prevent siphoning
- To keep a valve sealed
- To prevent reverse flow causing contamination
- To prevent reverse flow causing equipment damage
The nature of their functionality proves useful in household appliances such as dishwashers, wastewater lines, and washing machines, including more industrial purposes like boilers, pumping applications, gas systems, furnaces, and CO2 lines in aquariums. However, they are most commonly used in water and air applications.
Pneumatic Check Valve
Pneumatic check valves are automated and do not require any manual operation to open or close. They are often known as one-way air valves or air check valves; they allow airflow in and prevent it from coming out. They have a specified cracking pressure, the minimum pressure required to enable the valve to operate.
Check Valves for Water
Numerous water applications are home to check valves, such as drinking water and wastewater. Check valves in drinking water applications to ensure that no media from the outlet side of the valve can enter the system with clean drinking water and contaminate it. The same goes for wastewater applications; they ensure that the contaminated water cannot re-enter the system and cause an overflow.
TYPES OF CHECK VALVES
A check valve is the most straightforward directional control valve used in hydraulic systems. There are numerous check valves, all with defining characteristics that work more effectively with different applications.
BALL CHECK VALVES
Usually compact and cost-effective, ball check valves have a spherical moving part to block flow within a pipeline. It’s sometimes spring-loaded to help keep it shut, or otherwise, the reverse flow is required to move the ball toward the seat and create a seal.
SWING CHECK VALVES
Mounted with a disc that swings on a hinge or shaft, the disc swings off the seat to allow forward flow; when the flow stops, the disc swings back to the seat to block flow moving in reverse. Swing check valves need to be cleaned, so they aren't entirely maintenance-free -, so it's crucial to install them in a convenient place to be inspected.
Related products: S72 - Swing Check Valve
PISTON/LIFT CHECK VALVES
A disc features inside a piston/lift check valve that lifts up off its seat by higher pressure of the upstream fluid to flow to the outlet or downstream side. When the pressure drops, gravity or higher downstream pressure causes the disc to lower onto its seat, shutting the valve to stop reverse flow.
Related products: S27 - Piston Check Valve
Stop-check valves are used as a check valve or isolation valve. They can responsively stop flow irrespective of the flow direction or pressure in the pipeline, including being shot by an external component.
DUAL PLATE CHECK VALVES
A dual plate check valve is known by many names, such as a butterfly check valve, folding disc check valves, or double-disc. It features two halves of the disk move towards the center of the pipeline with the forward flow, and it closes with the reverse flow by two halves open and resting on the seat to close the flow. Lightweight and compact in its construction, it’s a low-cost installation and maintenance choice.
TILTING DISK CHECK VALVES
The tilting design feature allows the valve to open fully and remain steady at lower flow rates, ensuring it can close quickly when the forwarding flow stops. The disc has a bevelled seat on the body and the disc edge, allowing tight shut-off at any pressure.
WAFER CHECK VALVES
Wafer check valves are a compact and low-cost solution and are the preferred type of check valve for most applications. The valve opens and closes at extremely low-pressure moments over the valve disc.
ANGLE CONTROL VALVES
Angle control valves are often used in piping systems where space is required, such as drain services, boiler feedwater, and other piping services. The valve's body features a right angle, which prompts the directional change of the flow.
MICRO CONTROL VALVES
A micro control valve is a microscale valve, often less than 10mm, which features two ports to regulate flow. They are usually found in fluidics and microfluidics to control fluids or gases, and the valve is electrically controlled. Micro control valves are often used in the inlets and outlets of micropumps, where the liquid or gas is needed to flow in one direction.
CRYOGENIC SERVICE VALVES
Cryogenic service valves are suitable for use in very cold applications, ranging from -40 C to -196 C, and feature a long neck bonnet. They can help store and transport tons of cryogenic gasses such as Compressed Natural Gas or Liquefied Natural Gas; when heated, these gases can expand hundreds of times, becoming flammable and explosive.
A control valve is used to control the flow rate of fluids or gases using a controller. Allowing direct control of flow, pressure, liquid level, and temperature within the passage.