What Are The Best Valves For Slurry Applications?

What is slurry?

Slurry is a fluid that contains solid particles suspended in a liquid. Common applications where slurry is prevalent include mining, food processing, and wastewater treatment, among others. Slurry, like other fluids, can be toxic, corrosive, and abrasive. Therefore, it requires a properly selected valve for transportation.

What is a slurry valve?

A slurry valve is designed to control the flow of slurries. This is different from other valves as it is specifically designed and manufactured to handle corrosive and abrasive media. It is also meant to withstand high pressure and temperature. Various types of valves are used in slurries, and each piece of equipment is selected based on its advantages for the required application. Read ahead to know which valves fit, how they work, why they are used in slurries, and which factors to consider when purchasing such valves.

Slurry Ball Valve

A ball valve is a common valve used in almost all industries, including slurry applications. The reason for its widespread use is its simple and compact design. An actuator/handwheel is used to operate the valve. The component used to stop or control flow is shaped like a ball with a hole at its center. The ball and actuator/handwheel are connected by a metallic component known as the stem. The valve permits/blocks flow when the handwheel rotates for a quarter turn (90 degrees). Key advantages of this valve are:

• Quick to operate. It only needs a 90-degree turn to open/close.
• Simple and compact in design.
• Offers perfect sealing, ensuring zero leakage.
• Versatile in size and application.
• Has a low-pressure drop.

Figure: Slurry ball valve.

Knife Gate Valve

A knife gate valve operates by using linear motion to move its plate/gate/disc that permits or blocks flow. A handwheel/actuator helps to operate the gate. Similar to the ball valve, a valve stem connects the gate to the handwheel. The only challenge with this equipment is that it needs several turns of the handwheel for it to open/close. The stem has threads that convert the rotational force on the handwheel to linear motion. Movement of the stem upwards helps to move the gate from the flow path, allowing slurry flow. Moving the stem downwards helps the gate to move to its seating position, where the flow path is blocked, and the valve is closed. As the name suggests, this valve uses a knife-shaped gate that helps to cut up solids to enhance perfect closure. The advantages of this valve are:

• Versatile in size.
• Perfect closure.
• Bi-directional flow.
• More robust for extreme conditions.

Figure: Knife gate valve.

Slurry Check Valve

A slurry check valve is an automatic valve meant to prevent reverse flow. The valve is also known as a one-way valve or non-return valve. The valve does not have an actuator or handwheel as it operates automatically based on pressure level. The component used to prevent reverse flow is a plate/gate or ball-shaped component. When the pump starts moving the slurry, the flow pressure acts on the gate/ball component and forces it to open. When the pump stops or flow pressure reduces, the force acting on the gate reduces, and thus, the gate returns to its position where it instantly blocks any reverse flow. Advantages of this valve:

• Small in size relative to other slurry valves.
• Does not allow reverse flow.
• Automatic operation.
• It does not have an actuator or handwheel.
• It has a low-pressure drop.
• Versatile in size.

Figure: Slurry check valve.

Slurry Butterfly Valve

A slurry butterfly valve is a quarter-turn valve used for shut-off and controlling flow. It uses a component known as a gate/disc to stop or regulate flow. The equipment features a metallic seat to prevent abrasive and corrosive damage by the slurries. An actuator or handwheel is used to operate the valve disc. The disc and handwheel are connected via the stem. Rotation of the handwheel/hand lever for 90 degrees helps to turn the disc to permit or constrict the flow. The advantages of this valve are:

• Easy to install and repair.
• Quick to operate.
• Versatile in size.
• High efficiency due to low-pressure drop.
• Small in size and light in weight.
• Occupies a smaller space.

Figure: Slurry butterfly valve.

Factors to consider when selecting a slurry valve

• Type of slurry. There is abrasive and non-abrasive slurry. The abrasive slurry contains solids that may cause wear on the valve, while non-abrasive does not contain abrasive solids. Understanding the type of slurry helps in selecting the best valve.
• Valve size. Use the correct valve size to avoid leakage and damage to the environment.
• Operating temperature and pressure.
• Compatibility with slurry. Ensure the valve material is compatible with the slurry properties to avoid premature damage.