Control Valve Types (Gate Valve, Globe Valve, Ball Valve etc.)!

saVRee

9 Aug 201812:17

Summary

TLDRThis video script offers an insightful overview of various valve types, including globe, gate, ball, plug, butterfly, diaphragm, check, pinch, and safety valves. It explains how valves are named, their functions in controlling flow and pressure, and the differences between rotary and linear motion valves. The script also covers the advantages and disadvantages of each valve type, their ideal applications, and the role of actuators in their operation.

Takeaways

🔧 Valves are named after the type of discs they use, which control the flow of substances through them.
🌐 Globe valves are an exception, named for the shape of the valve body rather than the disc.
🔄 Valves serve various functions like stopping, starting, varying, controlling direction, regulating pressure, and relieving overpressure.
🔧 Rotary valves, such as ball, plug, and butterfly valves, require a 1/4 turn to change from open to closed positions and are fast-acting.
📉 Linear motion valves like gate and globe valves operate by raising or lowering the disc and are slower than rotary valves.
🛠️ Actuators for valves can be mechanical, electrical, hydraulic, or pneumatic, determining how the valve is operated.
🏐 Ball valves are not suitable for throttling due to their design, but they have a very low pressure drop when fully open.
🦋 Butterfly valves are advantageous for large applications due to savings in weight, space, and cost, and have a low pressure drop when open.
🔨 Diaphragm valves are ideal for handling corrosive or contaminated fluids due to minimal parts exposure to the medium.
🚰 Gate valves are simple, cheap, and have low pressure drop when open, but are not suitable for throttling and can be prone to wear and leakage.
🌡️ Globe valves have less seat leakage and are easier to open, but they have a higher pressure drop and can be noisy and heavy.
🤏 Pinch valves are simple, inexpensive, and have almost no pressure drop, making them suitable for slurries with suspended solids.
🔩 Plug valves are similar to ball valves but with a different disc shape, offering low pressure drop and adaptability for multiport applications.
🔄 Check valves prevent flow reversal in a system, using mechanisms like weight, back pressure, or springs to operate.
💉 Needle valves allow for fine adjustments in fluid flow, often used as metering valves due to their precise control.
🛡️ Relief and safety valves protect equipment from overpressure by gradually or rapidly opening to release excess pressure.

Q & A

What is the primary function of a valve?
-Valves are used for stopping and starting flow, varying the amount of flow, controlling the direction of flow, regulating downstream system or process pressure, and relieving system over and under pressure.
How do valves get their names?
-Valves are almost always named based on the type of discs used, such as ball, butterfly, and gate valves, which are named after their respective shapes. However, globe valves are named after the shape of the valve body itself.
What are the two main categories of valve motion?
-Valves can be categorized as rotary or linear motion valves. Rotary valves require a 1/4 turn to change position, while linear motion valves raise or lower the disc to control flow.
Why are ball valves not suitable for throttling or regulating flow?
-Ball valves are not suitable for throttling or regulating flow because they are designed for fast-acting, on-off control. The pressure drop across ball valves when fully open is very low, which is not ideal for throttling.
What are the advantages of butterfly valves over other valve types for larger applications?
-Butterfly valves offer advantages such as savings in weight, space, and cost, especially for larger applications. They also have a low pressure drop when fully open and are well-suited for handling large flows of liquids or gases at relatively low pressures.
How does a diaphragm valve operate and what makes it suitable for handling corrosive fluids?
-A diaphragm valve operates by raising or lowering a flexible diaphragm onto the valve seat to control flow. It is suitable for corrosive fluids because very few parts are exposed to the flowing medium, with only the diaphragm and internal flow passages in contact, preventing contamination.
Why are gate valves prone to excessive vibration when only partially open?
-Gate valves are prone to excessive vibration when partially open because the flow stream can cause the valve disc to vibrate, especially if the flow is turbulent or at high velocities.
What are the main designs of globe valves?
-The main designs of globe valves are straight flow, angle flow, cross-flow, and Y-flow, each offering different flow patterns and control characteristics.
How do pinch valves operate and what makes them suitable for handling slurries with large amounts of suspended solids?
-Pinch valves operate by compressing a sleeve made of rubber or synthetic material using a pinching mechanism. They are suitable for slurries with large amounts of suspended solids due to their large seating area and because the operating mechanisms are isolated from the flowing medium, preventing wear and contamination.
What is the purpose of a check valve in a piping system?
-A check valve is designed to prevent the reversal of flow in a piping system. It allows flow in one direction and closes when there is a reversal of flow, maintaining the correct flow direction and protecting the system.
How do relief and safety valves differ in their operation?
-A relief valve gradually opens as the inlet pressure increases above the setpoint to relieve overpressure, while a safety valve rapidly pops fully open once the pressure setting is reached and stays open until the pressure drops below a reset pressure, providing a quick response to overpressure conditions.

Outlines

00:00

🌐 Introduction to Valves

This paragraph introduces various types of valves, including globe, gate, ball, plug, butterfly, diaphragm, check, pinch, and safety valves. It explains the basic principle of how valves are named, usually after the type of discs they use, and their functions such as stopping, starting, varying, controlling, and regulating flow. The paragraph also distinguishes between rotary and linear motion valves, and outlines the four main types of actuators: mechanical, electrical, hydraulic, and pneumatic. Specific examples of rotary valves like ball, plug, and butterfly are given, as well as linear motion valves like gate and globe. The functions and characteristics of ball and butterfly valves are detailed, emphasizing their fast-acting nature and advantages in certain applications.

05:01

🚰 Detailed Analysis of Linear and Rotary Valves

The second paragraph delves deeper into the characteristics and applications of linear and rotary motion valves. It discusses the gate valve, explaining its suitability for starting or stopping flow without throttling and its advantages such as low cost, simple design, and minimal pressure drop when open. However, it also points out the disadvantages, including unsuitability for throttling and potential for vibration and wear. The globe valve is contrasted with the gate valve, highlighting its ability to regulate flow with different designs and less seat leakage, but also noting its larger pressure drop and the need for more power to operate larger sizes. The paragraph also covers pinch valves, which are simple and inexpensive, suitable for slurries with suspended solids, and plug valves, which are similar to ball valves but with a different disc shape, ideal for multiport applications and frequent operation. Lastly, it touches on check valves designed to prevent flow reversal and needle valves used for fine adjustments in fluid flow.

10:02

🔒 Valves for Flow Regulation and Safety

The final paragraph focuses on the specialized roles of check, needle, relief, safety, and solenoid valves. It describes check valves as crucial for preventing reverse flow in piping systems, activated by the flow itself and closed by various mechanisms depending on system requirements. Needle valves are highlighted for their precision in flow regulation, often used as metering valves due to the direct correlation between handwheel turns and flow amount. Relief and safety valves are presented as essential for preventing equipment damage by relieving overpressure, with relief valves gradually opening and safety valves popping open fully at a set pressure. Solenoid valves are introduced as electromechanically operated, fast-acting, and suitable for on-off operations but not for flow regulation, operated by an electromagnet and returned to a fail-safe position by a spring when current is cut off.

Mindmap

Keywords

💡Valve

A valve is a device used to control, regulate, or stop the flow of a fluid by opening, closing, or partially obstructing various passageways. In the video, valves are the central theme, with various types and their functions being discussed, such as ball valves, butterfly valves, and gate valves.

💡Disc

The disc is the part of a valve that is used to open, close, or regulate the flow through the valve. It is a critical component in the operation of valves. The script mentions that valves often get their name from the type of disc used, such as in ball valves where the disc is ball-shaped.

💡Throttling

Throttling refers to the process of regulating the flow of a fluid by partially closing a valve. It is a key function of certain valves, allowing for precise control over fluid flow rates. The script describes throttling in the context of valve operation, highlighting its importance in flow control.

💡Rotary Valves

Rotary valves are a type of valve that requires a 1/4 turn to change from fully open to fully closed positions. They are fast-acting and include ball, plug, and butterfly valves. The video explains that rotary valves are quick and efficient for stopping and starting flow.

💡Linear Motion Valves

Linear motion valves operate by raising or lowering the disc to control the flow. They are slower than rotary valves and include gate and globe valves. The script contrasts these with rotary valves, emphasizing their slower operation and different mechanisms for flow control.

💡Actuators

Actuators are devices that are used to operate valves. The video mentions four main types: mechanical, electrical, hydraulic, and pneumatic. Actuators are essential for the operation of valves, especially in automated systems where manual operation is not feasible.

💡Butterfly Valve

A butterfly valve is a type of rotary valve known for its fast operation and low pressure drop. It is used to stop, regulate, and start flow. The video highlights the butterfly valve's advantages, such as savings in weight, space, and cost, especially for larger applications.

💡Diaphragm Valve

A diaphragm valve is a linear motion valve that uses a flexible diaphragm to control flow. It is particularly suited for handling corrosive or contaminated fluids due to minimal exposure of parts to the flowing medium. The script emphasizes its suitability for specific fluid types.

💡Gate Valve

A gate valve is a linear motion valve used to start or stop flow but is not suitable for throttling. It has a simple design and low pressure drop when fully open. The video discusses the gate valve's advantages and disadvantages, such as its low cost and potential for vibration when partially open.

💡Globe Valve

A globe valve is a linear motion valve used to stop, start, and regulate fluid flow. It has different designs like straight flow, angle flow, cross-flow, and Y-flow. The video explains that globe valves have less seat leakage compared to gate valves and are often installed with system pressure on the underside of the valve seat.

💡Pinch Valve

A pinch valve consists of a sleeve made of rubber or synthetic material and a pinching mechanism. It is used to start, stop, or regulate flow with minimal pressure drop. The video notes that pinch valves are well-suited for handling slurries with large amounts of suspended solids due to their large seating area.

Highlights

Valves are named based on the type of discs used, which control flow.

Ball valves are identified by their spherical disc shape.

Butterfly valves resemble a butterfly and are fast-acting.

Globe valves are named after the shape of the valve body, not the disc.

Valves serve various functions including stopping, starting, and regulating flow.

Rotary valves require a 1/4 turn to change from open to closed positions.

Linear motion valves operate by raising or lowering the disc.

Actuators for valves include mechanical, electrical, hydraulic, and pneumatic.

Ball valves are not suitable for throttling due to their design.

Butterfly valves offer advantages in weight, space, and cost for large applications.

Diaphragm valves are ideal for handling corrosive or contaminated fluids.

Gate valves are simple, cheap, and have low pressure drop when fully open.

Globe valves have less seat leakage and are easier to open due to system pressure placement.

Pinch valves have minimal pressure drop and are suited for slurries with suspended solids.

Plug valves are similar to ball valves but have a different disc shape.

Check valves prevent flow reversal and come in various types.

Needle valves allow for fine adjustments in fluid flow.

Relief and safety valves protect equipment from overpressurization.

Solenoid valves are electromechanically operated and fast-acting.