Ball Check Valves

Check valves are unidirectional valves that ensure media flows in only a single direction. There are several check valve styles that perform unidirectional media flow like a ball, piston, or disk style. A ball check valve can prevent the backflow of various media like gas, air, steam, vapor, or water lines with high flow velocities. This article discusses the working and installation of a ball check valve.

Table of contents

• What is a check valve?
• What is a ball check valve?
• Materials
• Ball check valve specifications
• How to install a ball check valve
• Troubleshooting ball check valves
• Ball check valve advantages
• Ball check valve applications
• FAQs

What is a check valve?

A check valve is a type of one-way valve that allows fluid flow in only one direction. It consists of an inlet and outlet port, and its main function is to prevent backflow in a system. The valve opens and closes based on the pressure differential between the input and output sides and does not require external force to operate. Proper installation orientation is important for the valve to function correctly. Learn more by reading our article on check valves.

What is a ball check valve?

A ball check valve uses a spring-loaded or free-floating ball that rests on the sealing seat to close the valve orifice. A spring-loaded ball check valve is shown in Figure 2. The sealing seat is conically tapered to guide the ball into the seat and create a positive seal, thereby stopping reverse flow. When the fluid pressure in the inlet side exceeds the cracking pressure, the ball is dislodged from its seat, allowing fluid flow to occur (Figure 2 labeled A). When the inlet pressure doesn’t exceed the cracking pressure (pressure required to overcome spring force) or backpressure, the ball closes with the backpressure or via the spring, effectively closing the orifice (Figure 2 labeled B). A free-floating ball check valve is designed with no spring and requires an inverse flow or gravity to move the ball towards the seat to seal.

Ball check valves are commonly used in the plumbing industry, and these valves are designed to prevent the water from flowing backward through piping systems, sump pumps, and water heaters. Ball check valves can be manufactured with PVC, brass, or stainless steel, among other materials. The ball within the valve is typically constructed from metal, although other materials can also be chosen for the construction to increase durability. In general, ball valves have simple, inexpensive metallic parts, although specialized ball check valves are also available. For instance, synthetic ruby, which is a hard and chemically resistant material, is used to make the ball usable in high-pressure pumps in the analytical chemistry field.

Materials

Ball type check valves are made of various metallic and non-metallic materials. Most ball check valves have a rubber-coated ball with a metal core. When selecting a material, consider the following factors:

• Operating environment: The ambient heat of operation of the valve should be taken into account while selecting the housing materials. Brass is an excellent choice for the valve housing material at high temperatures.
• Lifespan (maintenance): Consider the average lifespan intended for the valve, which helps in analyzing the amount of maintenance required. Stainless steel ball check valves are highly resistant to wear and tear, temperature, and pressure.
• Media: PVC ball check valves are a great choice if the medium of operation is a gas or a corrosive liquid. However, these valves have lower pressure ratings than those made from brass and steel. Read our article on the chemical resistance of materials for more information on the compatibility of the valve materials to different media used.

Ball check valve specifications

Consider the following factors while choosing a ball check valve:

• Pressure drop: It is essential to know the pressure drop within the flow management system while selecting a ball check valve. The pressure changes in the system control the flow and hence the function of the ball check valve. The tightness with which the valve shuts off during backflow depends on the reverse pressure drop, where the downstream pressure exceeds the upstream pressure. A ball check valve requires a minimum pressure difference between its input and output ports. Choose a valve that complies with this need and consider the maximum pressure requirement while choosing a valve.
• Method of control: In a ball check valve, the fluid flows forward, but flow is prevented in the reverse direction. The backflow is prevented by the weight of the ball, back pressure, a spring, or at times by a combination of these mechanisms. Ideally, the ball check valve should provide zero resistance in the forward direction and full resistance to flow in the reverse direction.
• Connection types: Ball check valves can have various connection types, as discussed below:
• Flanged ball check valves: These valves have flanges on the inlet and outlet connections. The flange is sized and drilled in accordance with standards like EN 1092-2. Flanged ball check valves are used in plumbing, fire fighting, HVAC, and water/sewage treatment applications.
• Threaded ball check valves: These valves have internal or external threads for inlet or outlet connections.
• Ball check valves with compression fittings: These valves have a sealed pipe connection without any soldering or threading.
• Buttweld ball check valves: These valves have a butt weld connection for inlet or outlet ports.
• Soldered ball check valves: The ends of these valves are soldered to the pipe fittings. Read our article on soldering ball valves for more details.

How to install a ball check valve

This type of valve can be installed both horizontally and vertically in a piping system.

• Check the inside portion of the valve and remove any foreign particles present.
• Ensure that the ball moves freely by pushing it away from the seating surface.
• Inspect the valve ends and ensure that there are no raised burrs or edges that wouldn’t allow the valve to seal during operation.
• Install the valve according to the flow direction. An arrow symbol on the valve represents the direction of fluid flow through the valve.

Troubleshooting ball check valves

Noisy operation in ball check valves

Check the system piping for trapped air if the valve is noisy during operation. Also, a partly open valve may be extremely noisy; replace the ball with a lighter one in this case.

Ball check valves don't yield the desired flow

Check the valve internally for any foreign materials, and clean the valve thoroughly.

Ball check valve leaking back

A ball check valve is supposed to prevent backflow of fluid. If backflow occurs, disassemble the valve parts and check the valve seat and ball for possible damages.

Ball check valve advantages

• Small size
• Easy to use
• Inexpensive
• Can be installed in lines with both horizontal and vertical flow.
• Handles high pressure and large fluid volume with various media like gas, air, steam, vapor, or water
• Ball rotation ensures the valve’s self-cleaning
• Renewable seat rings are available

Ball check valve applications

• Sprinkler and piping systems
• Ball check valves are used to prevent backflow and keep potentially contaminated water from reentering water supply lines.
• Ball check valves are used in common household devices like liquid pump dispensers, spray devices, and dispensing syringes.
• Used in the injection molding process to push plastic forward and not allow any to slip backwards.

FAQs

What is the function of a ball check valve?

A ball check valve is used to pass fluid only in one direction and prevents the flow in the reverse direction.

What are the different types of check valves?

Check valves can have different mechanisms like a ball, diaphragm, lift, or swing to prevent backflow.