Check valves are essential components in many fluid systems, serving the important purpose of ensuring that fluid flows in a single direction. They are used in a variety of applications, such as industrial water and wastewater systems, and are designed to maintain a steady flow of fluid and prevent back flow.

Purpose of Check Valves

Check valves work by allowing fluid to flow in one direction while blocking any back flow. This is achieved by means of a valve body, which houses a spring-loaded disc or flap. When fluid enters the valve, it pushes against the disc or flap, opening it and allowing the fluid to pass through. When the fluid pressure decreases, the disc or flap closes, preventing any back flow.

Without check valves, systems can experience a sudden change in pressure, causing damage to pipes and pumps. In addition, check valves can prevent contamination of the system by preventing back flow of contaminated fluid from entering.

Swing Check Valve Vs. Spring Check Valve

Swing Check Valve

Swing check valves are a type of check valve that is operated by a lever or a weight. This type of check valve works by using a hinged disc to open and close the valve. The swing check disc is usually made of stainless steel, bronze, brass, ductile iron, or other corrosion-resistant materials. The disc is attached to a hinge that allows the disc to move, which is typically made of stainless steel, brass, or other durable materials. The hinge is held in place by two bolts.

The swing check is designed to move freely between an open and closed position based on water pressure. When the valve is in the open position, the swing check is in line with the flow of the liquid, allowing it to pass through the valve. 

When the liquid pressure decreases, however, the swing check valves will return to their vertical positions, preventing any back flow. Swing check valves are often used in water systems, as they are able to handle larger flow rates and are more durable than spring check valves.

Spring Check Valve

Spring check valves are a type of check valve that works by utilizing a spring to keep the valve closed. This type of check valve consists of a disc, a spring, and a housing. The spring provides the force to keep the valve closed, while the tilting disc is designed to open when the pressure on the outlet side of the valve is greater than that on the inlet side. This type of check valve is ideal for applications where a low flow rate is required and can be used in both water and gas systems. 

The spring check valve is typically installed in the piping of a liquid system and serves as a critical safety feature. For example, if the pressure in the system suddenly increases, the spring check valve will close, preventing any back flow or reverse flow of liquid. Spring check valves are also used in many other types of systems such as fuel, air, and oil. They are an important part of ensuring the safety and efficiency of any system that utilizes liquids or gasses.

The most common type of spring check valve is the ball check valve. This uses a ball inside the valve body to prevent reverse flow. When the pressure increases and the ball is pushed against the valve seat, it creates a tight seal that prevents the fluid from flowing in the wrong direction.