Industrial

An Overview of Ball Valves and their Usage

In specific settings where valves are needed to open and shut off the fluid flow, ball valves are often preferred to other control valves. These valves offer a leak-proof experience, are lighter, and provide multi-design flexibility that lets them find their applications in a wide range of environments. Below, we’ve discussed the working principle of a ball valve, the types, applications, and selection criteria. Keep reading to learn more.

What is a Ball Valve?

A ball valve is a shut-off valve used to control fluid flow with the help of a rotating ball with a bore. As the ball rotates around its axis, the fluid medium is either blocked or allowed to flow. Ball valves have a longer lifespan with reliable sealing. However, they aren’t always used as control valves due to their limited accuracy when controlling flow rates. They can be controlled mechanically with a lever or with a pneumatic or electric actuator for automation.

Ball Valve Working Principle 

Before we look at the ball valves working principle, let’s first acknowledge the five main ball valve parts. These five parts are the valve housing, a valve stem, a ball, a ball valve seat, and O-rings. The valve housing supports all of the components. The valve stem is connected to the actuation method on top (lever or actuator) and the ball on the bottom. The ball is supported in place by the valve seat and o-rings keep the media sealed to the valve housing. The ball has a hole through its cross-sectional surface. That means the hole allows the fluid to flow or restricts flow if you turn the ball at a 90-degree angle. 

To further understand how the ball valve operates, we’ll need to look at the ball valve’s circuit function, ball design, and housing assembly. Here’s a quick overview.

  • Circuit function – most ball valves are either 2-way, 3-way, or 4-way depending on how many ports are needed.
  • Housing assembly – the housing of the ball valve can either be one-piece, two-piece, or three-piece. One piece is cheap and often used in less-demanding fluid control settings. Two-piece and three-piece designs allow for more thorough cleaning, but a three-piece can be taken out when connected to a piping system.
  • Ball design – most ball valves have a floating ball configuration, while others feature a trunnion ball design.  

Ball Valves Types and their Applications 

Ball valves are classified into four main types based on their connection type and their unique features, mode of operation, and range of applications. The four types of ball valves are:

Standard/Threaded Ball Valves 

These valves receive their name from their threaded connection type. They are available in many varieties, each designed for their specific applications. This ball valve type is the most common in the market, having a wide range of material options and a wide operating range for temperature and pressure. Applications can range from domestic, business to industrial uses both for gas and liquid media.

Hydraulic

This type is designed for heating and hydraulic systems, thanks to their high-operating pressure rating. Hydraulic valves are made of stainless steel or steel, and their seats are made of POM (polyoxymethylene). The latter is designed for high pressure, low-temperature applications of up to 500 bar and 80°C.

Flanged 

Unlike the Hydraulic ball valve, the flanged type is characterized by its connection type. Flanged ball valves have a high flow rate due to their full-bore design. They also have different pressure ratings and varying flange-compression classes that determine the highest pressure the valve can withstand.

Vented 

This type has a similar design to threaded 2-way ball valves, only that it has a port/hole that releases pressure in a closed position. The vented ball valve finds application in compressed air systems common in the foods, chemicals, and semiconductor & electronics industries. Here, the valve is used to provide a safer environment by releasing excess pressure to the environment. 

Choosing the Right Ball Valve for Your Applications

Now that you know the different ball valves, their working principle, and use cases, let’s look at how you can select the right type for your unique applications. Here are the key factors to keep in mind.  

  • Operation type – Ball valves can be operated electrically, manually, or pneumatically. Depending on the working environment and type of application, you can choose a manual, budget-friendly ball valve or an automatic valve for faster and efficient operation.
  • Circuit function – A ball valve can be 2-way, 3-way, or 4-way, based on the number of ports and their unique use cases. 2-way valves are commonly used to provide straight flow paths from an input point to an output point. Ball valves with 3 or 4 ports allow for distribution, redirection, or mixing fluid medium for various applications. 
  • Housing material – the ball valve’s housing material should be compatible with the fluid you want to control. Common materials include PVC suitable for corrosive liquid such as seawater and acids, brass for neutral fluid media, and stainless steel for heavy-duty applications.
  • Seal Type – ball valves have two seals that should be compatible with the fluid it’s controlling. Common seal materials include FKM (Viton) with excellent mechanical and chemical resistance, EPDM suitable for steam, alcohols, ketones, etc., and Teflon (PTFE), ideal for high-temperature applications.
  • Connection Type & Size – ball valves come in varying sizes and connection types. Common types are standard/threaded connections, flanged connections for larger pipes, welded connections used in zero-leakage applications, and true union connections that allow for faster installation, quick repairs, and maintenance.
  • Temperature and pressure – some ball valves are designed to withstand higher temperatures and pressures than others. Similarly, some can operate well in frozen environments, such as stainless steel ball valves.Flow rate – this is determined by the ball valve’s flow coefficient (kv). The higher the flow coefficient, the higher the flow rate.
  • Approvals and Standards – some applications require ball valves that are rated and approved by specific regulatory bodies. For instance, valves for drinking water applications require KIWA, DVGW, or WRAS approvals, while those used to control gas medium require EN-331 or DVGW approvals.

Final Thoughts 

Ball valves find applications in different settings and are often used to control and shut off liquid and gases as well as corrosive fluids and slurries. When buying a ball valve for your varied applications, always consider the factors we’ve identified above. You also want to do your research and choose a reputed manufacturer in the market.

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