Since there are different types of valves in the market today, getting to choose the right valve as a plumber or a property owner could be very challenging. In this guide, we will help you understand the two most popular valves in the market; ball and stop valves.
We will discuss in detail their differences in terms of function, symbol, advantages, limitations, structure, principle, and applications.
What is Ball Valve?
A ball valve is a metal valve made up of a ball-shaped object with a bore to control, allow, and stop the flow of gases, liquids, and vapors. A shaft connected to the control system helps rotate the ball to allow or obstruct the flow. The ball valve functions by partially opening, fully closing, or fully opening.
What is Stop valve?
A stop valve or shut-off valve is a linear motion valve that can only stop or allow fluid flow but cannot control it. This is because it is either fully opened or closed but can’t be partially opened, giving it the name, of a stop valve.
How Ball Valve vs. Stop valve Compare
Ball Valve Function
With a ball that can rotate at the centre of the valve, the fluid flow can be stopped, allowed or controlled. Turning of the ball at 900 through the stem manually or pneumatically will stop or allow the fluid flow through the pipe. While turning the stem, the fluid flow can also be controlled to a partial flow.
Stop Valve Function
A stop valve functions by completely cutting off the flow of a liquid running through a pipe. Think of an electric switch, the stop valves function in the same way. They fully open the flow or completely stop it.
Ball Valve Symbol
The symbol used for a ball valve takes an X-shape with an outlined center circle to show that the ball can rotate to allow, obstruct, or control the flow. Take a look at the symbol below.
Stop Valve Symbol
Stop valve is usually symbolized by an image that takes the shape of a bowtie with two lines at the end of each triangle. This is to indicate the on or off application of a stop valve. The symbol is as indicated in the picture below.
Ball Valve Advantages
Ball valves are also easy to maintain once installed and can be used for years without any problems, they also don’t need lubrication.
Another advantage is that the ball valves are made of durable materials and can last for longer compared to stop valves.
In terms of operation, ball valves are user-friendly and can be operated by anyone.
Stop Valve Advantages
A stop valve is cheaper and offers quality service when used with the right applications.
In terms of maintenance, stop valves are easy to maintain and do not require longer or complicated procedures to maintain.
Stop valves are also very easy to handle during installation and operation.
Unlike other types of valves, stop valves don’t require any kind of lubrication, hence cutting on maintenance costs.
Ball Valve Limitations
Since the ball valve is a sealed unit, it is very difficult to repair.
They also have limited flow control ability and because of this, they are not suitable for some applications.
Ball valves are also more expensive due to their durability and high-pressure applications.
Stop Valve Limitations
Stop valves and limited to some applications because they can’t handle high-pressure applications.
They are also not as durable as the ball valves are.
Design and Structure
Ball Valve Structure
A ball valve is made up of five main parts; the valve stem, the O-rings, the valve housing, the ball, and a seat. A connection between the valve stem and the ball allows the valve to be manually or automatically controlled. The O-rings and the seat support and seal the ball while the valve housing holds everything together. Remember the ball has an opening called a bore.
Stop Valve Structure
A stop valve is made of a valve, a valve seat, a hand wheel, a spindle, a gland, a yoke, a stud, and a fluid passage. The valve stops the flow when pressure is applied of the valve seat through the hand wheel. The fluid passage allows fluid flow when no pressure is applied to the seat.
Working Principle of a Ball Valve
The ball valve is designed with a ball that has a bore or a hole that runs through it. When the valve stem is moved manually or pneumatically, it can stop, allow, or control the flow of a fluid in the pipe. A quarter turn on the stem, can either stop or allow the fluid flow.
Working Principle of a Stop Valve
Working of a stop valve is as simple as moving the valve up and down, when the valve is up the fluid flows through. When the valve is pressed down through the hand wheel, the fluid flow is stopped.
Application of pressure either manually or pneumatically to the valve flap will seal the surface of the flap and in return seal the surface of the seat.
When the seat is sealed it closely fits in the opening to prevent the fluid flow. Removing pressure from the valve flap removes the seal and the fluid can flow again.
Ball Valves Applications
Ball valves are recommended for applications that involve high-pressure requirements such as onshore or offshore gas and oil production lines.
Ball valves are also good for hydrocarbon systems and other gas, vapor, and air systems.
Also, applications that involve high-temperatures like hot water shower lines can use ball valves.
Stop Valves Applications
Stop valves are applicable in plumbing systems that don’t involve very high pressure such as dishwashing machines, washing machines, water supply taps for residential use, water supply for the gardens, and bathroom water supply.
From the comparison above, you can be able to tell which of the two valves is suitable for your kind of application. Remember ball valves can handle high pressure while stop valves can handle low-pressure ones. Also, it is important to know the valve symbol in order to make the right choice during your purchase.