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Motorized Ball Valve

March 27, 2022

What is a motorized ball valve?

A motorized ball valve is a type of ball valve that uses electricity to operate. This type of valve uses a perforated, hollow, and turning ball to control fluid flow. Motorized ball valves have the ball with a hole at the center. An electric motor is used to control the position of the ball to enhance fluid flow or block fluid flow. Motorized ball valve manufacturers design the ball such that it can control, direct, guide, and modulate fluid flow. The motorized ball valve can work in gases, liquids, and vapors. Motorized ball valve closes or opens flow by turning the ball 90^o anticlockwise or clockwise direction respectively. A motorized ball valve initiates fluid flow when the ball hole turns to be parallel to the fluid flow direction. Motorized ball valves are known for long service life and high reliability.

Figure: Motorized ball valve.

Components of motorized ball valve

Valve body/valve housing

The valve body or valve housing in a motorized ball valve is the component used to contain all internal parts of the valve. The valve body is made of strong, hard, and rigid materials so that it can have high strength enough to withstand high pressure and high temperatures associated with the fluid flow. The inlet and outlet ports of a motorized ball valve are also made on the valve body.

Rotary ball

The ball is a spherical component with a hole in its middle. The hole at the center of the ball is known as a bore. The hole or bore in the ball serves as the opening to the fluid flow. The ball in a motorized ball valve can be a hollow ball or solid ball. For a solid ball, there is a constant opening diameter which enhances smooth fluid flow at constant velocity. For a hollow ball, the space inside it enhances more fluid to flow through the valve. However, hollow balls in a motorized ball valve tend to have more turbulence as well as high velocities. Nevertheless, a hollow ball in a motorized ball valve makes the valve light in weight and cheap relative to a solid ball.

Stem (shaft)

This is the component of a motorized ball valve that connects the electric motor to the ball. The stem is a shaft that transmits power from the electric motor to operate the motorized ball valve. The stem in a motorized ball valve is designed with seals like O-rings and packing rings for sealing the bonnet as well as the stem/shaft to prevent fluid leakage.

Bonnet

Bonnet in a motorized ball valve is the component placed on top of the valve body to cover internal parts. The bonnet and the valve body in a motorized ball valve are connected using screws or bolts and nuts or by welding to ensure it is leakage free. Just like the valve body, the bonnet should be made of strong, hard, and rigid materials that can withstand high pressure and high temperatures according to the intended use of that valve.

Seat

The seat in a motorized ball valve is a component used to provide a seal between the valve body and the ball. There is an upstream seat adjacent to the valve inlet side and a downstream seat placed opposite to the upstream seat adjacent to the valve discharge side.

Actuator

The actuator is the component is a motorized ball valve that is used to provide the power to operate the valve. The actuator is an electric motor. The actuator can be automatic or semi-automatic.

Packing

Packing refers to the seal around the valve stem/shaft used to prevent fluid leakage.

Figure: Components of a motorized ball valve.

How does a motorized ball valve work?

Motorized ball valves work by converting electrical energy into mechanical energy. It is the mechanical energy that is used to open/close motorized ball valves. The electrical energy is converted into mechanical energy by the use of an electric motor. The working of a motorized ball valve is discussed below.

Power to the system. The motorized ball valve is opened by turning on electric power. This allows the electric current to flow to the electric motor. This turns the electric motor on making it rotate and thus start rotating shaft that transmits mechanical power to open the valve. The power required to open a motorized ball valve depends on certain factors such as its size. In most cases, the power required to operate a motorized ball valve could be 12V, 24V, or 48V of DC power or 24V, 48V, 120V, or 240V of AC power.
The power from the electric motor is transmitted via a set of gears to help reduce its speed and simultaneously increase its torque (because speed and torque are inversely proportional). As such, the motorized ball valve actuator will be able to produce different levels of torque or force based on the gear train set controls. The torque from the gear trains is used to turn the stem of the motorized ball and since the stem is connected to the ball it will turn it as it may be needed.

Figure: Working of a motorized ball valve.

Types of motorized ball valves

Single-body motorized ball valve

This is a motorized ball valve with one body. This motorized ball valve is designed with a solid cast valve body which reduces leakage. The single-body motorized ball valve is the cheapest of all motorized ball valves. However, this ball valve cannot be opened for cleaning or maintenance. The single-body motorized ball valve is used in less demanding functions. These valves have a small opening, they are cheaper, and they are generally disposable.

Two-piece body motorized ball valve

This is a motorized ball valve that consists of two parts in which the first component contains the body and end joint, the second component is attached to the first component. A two-piece motorized ball valve can be disassembled easily for inspection, cleaning, and maintenance. To separate the two pieces in this motorized ball valve, it has to be completely disconnected from the pipeline.

Three-piece body motorized ball valve

This is a motorized ball valve made with three parts that are the body and two end joints. The three components are connected using bolts and nuts. This design of a three-piece ball valve makes it easy to remove core parts of the valve such as stem, seat, and ball from the piping system. Such design of a motorized ball valve enhances effective removal of clogged materials, replacement of seals and seats without removal of tubing from the body. However, this type of motorized ball valve is sold at a higher price.

Top entry motorized ball valve

This is a motorized ball valve in which the ball is assembled from the side part of the top section. This design of a motorized ball valve enhances ball and seat repair without disassembly of the valve. The motorized top entry ball valve enhances a larger valve body. In most cases, motorized ball valve manufacturers design the valve such that you do not need to remove it from the pipeline. The advantage of top-entry motorized ball valves is that they have minimal thread connections which reduce leakages.

Side entry motorized ball valve

This is a motorized ball valve in which the ball is assembled from the side part of the valve. In most cases, this motorized ball valve has the ball assembled in two or three parts of the valve body. Each part is assembled with screws or bolts similar to connecting two flanges. Side entry ball valves have minimal defects from the manufacturing process and are easy to assemble.

Welded body motorized ball valve

This is a motorized ball valve that is fully welded making it free from any leakage. This type of motorized ball valve cannot be repaired like the other motorized ball valves. Welded body motorized ball valves are used in underground and buried applications where maintenance is not needed such as in gas transport and subsea transport applications. After these motorized ball valves are welded they are taken through non-destructive testing (NDTS) to ascertain that it has zero leakage.

Applications of motorized ball valves

Motorized ball valves are used in water and irrigation treatment applications.
Motorized ball valves are used in food and beverages processing.
They are used in the gas and oil industries.
These valves are used in pharmaceutical industries.
Motorized ball valves are used in power plants.
They are used in homes for control of water in a dish and clothe washing machines.
They are used in the automotive industry.
Motorized ball valves are used in chemical manufacturing plants.

Advantages of motorized ball valves

Motorized ball valves are easy to use. These valves are comparatively easy and quick to install, repair do maintenance.
Motorized ball valves have high efficiency. These valves do not need lubrication and they have tight seals which ensure no fluid and flow pressure is wasted.
Motorized ball valves are affordable as they employ a simple design relative to other valves.
Motorized ball valves have long service life especially when they are used according to the manufacturer’s instructions.
Motorized ball valves design employs strong material relative to the intended use which makes them withstand flow conditions like pressure.
Motorized ball valves are versatile as they are used in a wide range of applications.

Disadvantages of motorized ball valves

Motorized ball valves experience high tear and wear when used for the wrong application.
Motorized ball valves are not ideal for throttling applications.

Troubleshooting motorized ball valves

Ball seat leakage

Foreign matter around the ball seat. Clean/remove the foreign materials or replace the ball seats if it has been damaged by the materials.
The ball seat was damaged because it was used when half-open. Replace the ball seat. Use the valve when it is fully open/closed.
Ball seat damaged by thermal heat. Replace the ball seat with the one recommended by the motorized ball valve manufacturer.

Body gasket leakage

Loose bolts, nuts, or screws. Tighten the bolts or screws equally.
The body gasket is damaged. Replace the gasket.

Gland packing leakage

Loose gland bolt. Tighten the gland bolts diagonally and with equal torque.
Gland packing is worn out. Replace gland packing.

The actuator is not working

Switch, wires, or other leads are loose or disconnected. Inspect and re-connect accordingly.
A capacitor is not connected correctly or is loose. Check the wiring diagram as per the motorized ball valve manufacturer’s instructions and connect it accordingly.
Thermal overload protection is on. Give the electric actuator some time to cool down and minimize the operating frequency.
Terminal block wires are disconnected or loose. Inspect and connect them accordingly.
The motor is not operating or is damaged. Replace the motor.

The motorized ball valve motor is stalled while power is on

A capacitor has failed. Replace the capacitor.
The motorized valve needs more torque. Check for any obstructions and remove/clean.
The motorized ball valve control board components have failed. Inspect the components, rewire and or replace them.

Summary

A motorized ball valve is a type of ball valve that operates by use of an electric motor. This motorized ball valve employs electricity as its source of energy. The electricity is used to power the electric motor which then converts electrical energy to mechanical energy. The mechanical energy is used by the electric motor to turn the motorized ball valve on to allow fluid flow. Motorized ball valves use a ball that turns 90^o to close/open fluid flow. Motorized ball valves are suitable for on/off applications. Motorized ball valves manufacturers design the valve considering their ability to withstand fluid pressure and temperature. Motorized ball valves are used in different applications such as power plants, food and beverages processing, oil and gas, pharmaceuticals, water supply, and irrigation systems among others. Motorized ball valves are energy-efficient, affordable, durable, easy to use, versatile, strong, and simple to clean and repair.