Choosing the right valve for a particular application is critical to performance and safety. The valve actuator is at the heart of this choice, which triggers the valve to open or close. Valve actuators come in different types: electric, hydraulic, and pneumatic. Let’s compare single and double-acting pneumatic actuators, particularly in the context of NIBCO valves.
What is a Single-Acting Actuator?
Single-acting actuators, also known as spring-return actuators, use air pressure to open or close a valve. A mechanical spring is used for the opposite action. These actuators come with a fail-safe design, ensuring that if power or air pressure is lost, the valve reverts to its default (either open or closed) position. This is particularly useful in applications where the incorrect position of a valve can lead to serious repercussions. Drawbacks include:
- Cost: The mechanical springs add to the overall cost of the actuator.
- Durability: Springs can fatigue over time, becoming the first component to fail.
- Size: The actuator’s form factor tends to be larger due to the inclusion of springs.
What is a Double-Acting Actuator?
Double-acting actuators use air pressure for both opening and closing the valve. This eliminates the need for a mechanical spring, providing several advantages which include:
- Cost: Generally, it is less expensive due to the absence of springs.
- Durability: Tend to be more durable and capable of cycling millions of times before failure.
- Compact Size: Smaller form factor as compared to single-acting actuators.
Application-Specific Choices
- When to Use a Single-Acting Actuator – Choose single-acting actuators for applications that require a fail-safe mechanism and where the valve’s position could present a safety hazard. They are most suited for low- to moderate-cycle applications.
- When to Use a Double-Acting Actuator – These actuators are ideal for high-cycle applications and situations where the valve position isn’t critical during a power loss. They are often the go-to choice for applications requiring a compact form factor.
- Innovations: Double-Acting with Failsafe – A double-acting pneumatic actuator with a fail-safe feature combines double-acting actuators’ durability with a fail-safe mechanism’s reliability.
Spotlight on NIBCO Valves
NIBCO’s Series NDA/NSR pneumatic actuators feature double-acting and spring-return options. These actuators come with a patented spring design and a durable extruded anodized aluminum body, making them suitable for quarter-turn applications like ball valves, butterfly valves, and plug valves. With a unique 3-point load-bearing design and twin guide bars on pistons, these actuators offer smooth operation and exceptional torque.
Key Features of NIBCO Actuators:
- Durable extruded anodized aluminum housing.
- Unique 3-point load-bearing design.
- Twin guide bars on pistons for optimum rack and pinion engagement.
Selecting the appropriate type of actuator involves understanding the specific requirements of an application, including safety concerns, durability, and costs. Single-acting actuators provide a reliable fail-safe option but may be more expensive and less durable than their double-acting counterparts. On the other hand, double-acting actuators offer durability and cost-efficiency but may not be suitable for applications requiring a fail-safe mechanism. With companies like NIBCO offering a range of both types tailored to various industrial needs, your choice can be more precise and application-specific.