Attention engineers: why gate valves are a no-go for throttling

Gate valves are widely used in various industrial applications due to their simple design and reliable performance. However, when it comes to throttling flow, gate valves prove to be unsuitable due to several inherent limitations. This blog post delves into the reasons why gate valves should not be used for flow throttling, exploring the potential risks and adverse effects associated with this practice.

Understanding Throttling Flow

Throttling flow involves intentionally restricting the flow of a fluid to control its pressure or flow rate. This is typically achieved by partially closing a valve, thereby creating a pressure drop across the valve. In ideal throttling applications, the valve should provide precise control over the flow rate while minimizing pressure fluctuations and cavitation.

Drawbacks of Using Gate Valves for Throttling Flow

Gate valves, on the other hand, are not well-suited for throttling flow due to the following drawbacks:

1. High Pressure Drop

Gate valves have a wedge-shaped disc that slides perpendicularly to the flow path. When partially closed, the disc creates a significant obstruction to the flow, resulting in a high pressure drop. This can lead to excessive energy loss and system inefficiency.

2. Cavitation

The high pressure drop across a partially closed gate valve can cause cavitation, a phenomenon where the fluid vaporizes due to low pressure. Cavitation can damage valve components, generate noise, and lead to vibration.

3. Seat Damage

The wedge-shaped disc of a gate valve is not designed for precise throttling. When used for this purpose, the disc can repeatedly impact the valve seat, causing damage and potential leakage.

4. Erosion

Throttling flow through a gate valve can create high-velocity jets that erode the valve seat and disc. This erosion can compromise valve integrity and reduce its lifespan.

5. Noise and Vibration

The turbulent flow created by a partially closed gate valve generates noise and vibration. These can be detrimental to the surrounding equipment and work environment.

6. Control Limitations

Gate valves offer limited control over flow rate compared to other valve types specifically designed for throttling. The wedge-shaped disc may not provide the fine adjustment necessary for precise flow regulation.

7. Maintenance Concerns

Gate valves used for throttling require frequent maintenance to mitigate seat damage and erosion. This can increase downtime and operational costs.

Suitable Alternatives for Throttling Flow

Instead of gate valves, the following valve types are more suitable for throttling flow:

• Globe valves
• Butterfly valves
• Ball valves
• Control valves

These valves are designed with features that minimize pressure drop, cavitation, and noise, while providing precise flow control.

Final Note: Rethinking Gate Valve Applications

While gate valves are versatile and reliable for many applications, they are not suitable for throttling flow. Their inherent drawbacks can lead to performance issues, damage, and increased maintenance costs. By understanding these limitations and selecting the appropriate valve type for throttling applications, industries can optimize their systems, reduce downtime, and enhance overall efficiency.

Frequently Asked Questions

Q: Can gate valves be used for any type of flow control?
A: No, gate valves are suitable for on/off applications and should not be used for precise flow control or throttling.

Q: What are the consequences of using gate valves for throttling flow?
A: Excessive pressure drop, cavitation, seat damage, erosion, noise, vibration, and control limitations.

Q: What is the best valve type for throttling flow?
A: Globe valves, butterfly valves, ball valves, and control valves are more suitable for throttling flow due to their design features.