Industrial Valve Actuation: Manual, Pneumatic or Electric?
A valve is only useful if it can be operated reliably.
For industrial plants, choosing the correct industrial valve actuation method can affect safety, automation, maintenance and operating efficiency.
The three common approaches are:
- Manual
- Pneumatic
- Electric
Each has advantages and limitations.
What Is Valve Actuation?
Actuation is the method used to move a valve between its operating positions.
A manually operated valve relies on an operator.
An automated valve uses an actuator.
The actuator receives an instruction and moves the valve.
Manual Valve Operation
Manual operation can be suitable for valves that are:
- Infrequently operated
- Easily accessible
- Not required for rapid isolation
- Located where automation is unnecessary
Common manual options include:
- Handwheels
- Hand levers
- Gearboxes
Manual operation can be simple and reliable.
Pneumatic Actuation
Pneumatic actuators use compressed air.
They are widely used in industrial environments where compressed air is readily available.
Potential advantages include:
- Fast operation
- Simple control
- Suitable for automation
- No electric motor at the valve
However, the plant must have a suitable compressed-air system.
Electric Actuation
Electric actuators use an electric motor to operate the valve.
They can provide precise automated control and integration with plant control systems.
They may be suitable where:
- Electrical infrastructure is available
- Precise positioning is required
- Compressed air is unavailable
- Remote operation is required
Which Actuator Is Best?
There is no universal answer.
Consider:
- Valve size
- Operating force
- Required speed
- Cycle frequency
- Plant automation
- Available utilities
- Environment
- Fail-safe requirements
- Maintenance
- Control system
What About Mining?
Mining environments can be demanding.
Equipment may be exposed to:
- Dust
- Moisture
- Vibration
- Corrosion
- Temperature variation
Actuator selection should therefore consider the installation environment.
Fail Position
Some automated valves need to move to a defined position when the control system or utility fails.
Depending on the application, this may involve:
- Fail open
- Fail closed
- Fail in position
The appropriate configuration depends on the process safety requirements.
Final Thoughts
Choosing an actuator should be part of the original valve specification.
The right industrial valve actuation method can make a significant difference to operation and maintenance.
CMO Africa can assist with valve and actuation requirements for mining, water and industrial applications.
FAQ
What are the main types of industrial valve actuation?
The main types are manual, pneumatic and electric actuation. Hydraulic actuation is also used in some industrial applications.
Which actuator is best for a knife gate valve?
The correct actuator depends on valve size, operating force, cycle frequency, available utilities, automation requirements and safety requirements.