Side-Mounted vs. Traditional Pneumatic Actuators

 
In the field of industrial automation, pneumatic actuators are crucial control devices widely used for switching and regulating fluids. Among the common types are side-mounted pneumatic actuators and traditional pneumatic diaphragm actuators, each with its own unique structure and working principles. This article provides a detailed comparison of these two types of actuators, focusing on their structural characteristics, operating principles, advantages, disadvantages, and application scenarios. The goal is to help users choose the most suitable pneumatic actuator for their needs.

Structural Characteristics

The structural design of pneumatic actuators is vital to their performance. Side-mounted and traditional pneumatic diaphragm actuators differ significantly in structure. The former utilizes a lever mechanism for increased force, while the latter is characterized by a simpler design. Below, we compare the specific structures of these two types of actuators.

1. Side-Mounted Pneumatic Actuator Structural Features

Also known as a force-amplifying actuator, the side-mounted pneumatic actuator features a diaphragm mounted on the side of the frame. Key characteristics include:
Lever Mechanism: By using leverage, this actuator increases the output torque, making it suitable for applications requiring high output force.
Flexibility: It allows easy switching between direct and reverse action. Users can simply adjust the position of the connecting pin to change the operating mode.
Easy Installation and Adjustment: Users can easily open the front panel and rear cover to insert the connecting pin into a new hole, adjusting the stroke or working mode without changing other components.

2. Traditional Pneumatic Diaphragm Actuator Structure

The traditional pneumatic diaphragm actuator has a relatively simple structure, typically divided into direct-acting and reverse-acting types. Its main features include:
Separated Action Forms: In the direct-acting type, increasing signal pressure moves the push rod downward, while in the reverse-acting type, it moves upward, accommodating different control needs.
Wavy Diaphragm: Air pressure enters the air chamber through the wavy diaphragm, controlling the displacement of the push rod to open and close valves.
Simple Structure: Its overall design is straightforward, making it easy to maintain and replace parts.

Operating Principles

The operating principles of pneumatic actuators determine their mode of operation and efficiency. The side-mounted pneumatic actuator uses a lever mechanism and air pressure signals to achieve motion, while the traditional pneumatic diaphragm actuator relies on a wavy diaphragm and air pressure changes to control the push rod. Below is a detailed explanation of how these two actuators work.

1. Side-Mounted Pneumatic Actuator Principle

In the side-mounted pneumatic actuator, when the air pressure signal is sent to the air chamber, the resulting horizontal force causes the push rod to rotate the rocking arm counterclockwise. The process is as follows:
Air Close Action: The push rod pushes the valve core down to achieve air closure. This is considered direct action when the connecting plate is on the right side of the rocking arm.
Air Open Action: If the connecting plate is adjusted to the left side of the rocking arm, the valve core moves upward, indicating reverse action.
Stroke Adjustment: By changing the position of the connecting pin, users can quickly adjust the stroke or working mode, enhancing operational flexibility.

2. Traditional Pneumatic Diaphragm Actuator Mechanism

The working principle of the traditional pneumatic diaphragm actuator is straightforward:
Air Pressure Signal: The signal pressure enters the air chamber through the upper and lower sides of the wavy diaphragm, creating a force that drives the push rod to move.
Proportional Characteristics: The displacement of the push rod is proportional to the input air pressure signal; higher signal pressure results in greater push rod movement, demonstrating good linear characteristics.
Stability: When the spring's counteracting force balances the force on the diaphragm, the push rod stabilizes at a new position, allowing precise flow control.

Advantages and Disadvantages Comparison

Understanding the advantages and disadvantages of pneumatic actuators helps in selecting the right equipment. The side-mounted pneumatic actuator excels in output force and flexibility, while the traditional pneumatic diaphragm actuator is favored for its simplicity and stability. Below, we analyze the pros and cons of each.

1. Advantages and Disadvantages of Side-Mounted Pneumatic Actuators

Advantages

High Output Torque: Thanks to its lever mechanism, this actuator can provide greater output force, making it suitable for large-diameter valves and heavy loads.
High Flexibility: Its design allows users to quickly switch between direct and reverse actions, adapting to various process requirements and significantly improving operational efficiency.
Simple Adjustment: Adjusting the stroke and working mode is relatively easy; users only need to change the connecting pin's position without reassembling other parts, saving maintenance time and costs.

Disadvantages

Relatively Complex Structure: Due to its complex lever system, manufacturing and maintaining side-mounted actuators may require more specialized knowledge and experience.
Higher Costs: The complex design and increased output force can lead to higher procurement costs, making it potentially unsuitable for budget-limited small businesses.

2.  Advantages and Disadvantages of Traditional Pneumatic Diaphragm Actuators

Advantages

Simple Structure: The traditional pneumatic diaphragm actuator has a relatively simple design, making it easy to manufacture and maintain, which is why it is popular in many standard applications.
Strong Reliability: Due to its stable working principle and simple structure, it performs excellently during long-term operation, making it suitable for various industry applications.

Disadvantages

Limited Output Force: Compared to side-mounted actuators, traditional pneumatic diaphragm actuators have lower output force, which may not be sufficient for large-diameter or high-load applications.
Lower Flexibility: Although different structures can be selected for direct and reverse actions, the conversion process is relatively slow, lacking the flexibility of side-mounted actuators.

Application Scenarios

Pneumatic actuators are suitable for a variety of applications, with different structures and performance levels meeting various industrial needs. Side-mounted pneumatic actuators are ideal for high-load applications, while traditional pneumatic diaphragm actuators excel in small to medium control systems.

1. Side-Mounted Pneumatic Actuators Application

Due to their force-amplifying characteristics and flexible action conversion, side-mounted pneumatic actuators are particularly suitable for:
Large-Diameter Valve Control: They perform exceptionally well in applications requiring high output force, such as in the petrochemical and power generation industries.
Frequent Mode Changes: In process control situations where flexible adjustments are needed, side-mounted actuators can respond quickly to diverse control demands.

2. Use of Traditional Pneumatic Diaphragm Actuators

The traditional pneumatic diaphragm actuator, due to its simple and effective design, is suitable for:
Medium to Small Diameter Valve Control: It is ideal for applications in water treatment, pharmaceuticals, and the food industry, where flow control precision is crucial but output force requirements are lower.
General Fluid Switching and Flow Regulation: In situations that do not require high precision, these actuators provide stable and reliable control, making them suitable for everyday operations and maintenance.

Conclusion

When selecting a pneumatic actuator, side-mounted and traditional pneumatic diaphragm actuators each offer unique advantages. The side-mounted actuator, with its strong output force and flexible functionality, is well-suited for high-load and complex industrial applications. In contrast, the traditional pneumatic diaphragm actuator is widely used in small to medium fluid control systems due to its simple structure and good stability.