4-Step Guide to Selecting Pneumatic Actuators for A Customer From Guyana Buy 50 Sets Control Valves

How to select the correct multi spring diaphragm pneumatic actuator, our engineering team has prepared a simple "4-Step Selection Method" . This approach is centered on "Fail-Safe Logic" —ensuring that in an emergency, the valve protects your equipment and personnel.

Step 1: Determine the Fail-Safe Position — The Foundation of Selection

Imagine this scenario: If there is a sudden power outage or loss of air supply, what position should the valve be in to ensure process safety?

• Option A: Valve must be FULLY OPEN (for pressure relief, cooling, or to prevent over-pressurization).

  • Selection: Air-to-Close (Fail-Open). Air pressure closes the valve; loss of air opens it.

  • This typically corresponds to our Direct-Acting Actuator (SGMA Series) .

• Option B: Valve must be FULLY CLOSED (to stop media flow or isolate a hazard).

  • Selection: Air-to-Open (Fail-Close). Air pressure opens the valve; loss of air closes it.

  • This typically corresponds to our Reverse-Acting Actuator (SGMB Series) .

Step 2: Understand "How It Moves" — Direct vs. Reverse Action

To help you visualize how the actuator works internally, here is a simple analogy:

• Direct Action (SGMA): Like sitting down on a chair that compresses. When air is applied, the stem extends downward.

• Reverse Action (SGMB): Like sitting down, but the chair pushes up. When air is applied, the stem retracts upward.

Step 3: Decide "How to Control" — Selecting Accessories

This step depends on the valve's role in your process.

• Scenario A: On-Off Control

  • Application: The valve only needs to be fully open or fully closed (e.g., tank emptying, filling, emergency isolation).

  • Configuration: Solenoid Valve only. You can choose single-coil or double-coil based on your logic.

• Scenario B: Regulation Type Modulating Control

  • Application: The valve needs to precisely regulate flow, pressure, or temperature (e.g., heater control, flow ratio adjustment).

  • Configuration: A Positioner is MANDATORY. It receives a 4-20mA signal and positions the valve accurately.

  • Positioner Setting Reference:

    • For Air-to-Open valves: Positioner is usually set to Direct Action (4mA = valve closed, 20mA = valve fully open).

    • For Air-to-Close valves: Positioner is usually set to Reverse Action (4mA = valve open, 20mA = valve fully closed).
      Note: If using a modern "Smart" positioner, this is typically handled by auto-calibration.

Step 4: Confirm Special Requirements — Adding Advanced Functions

If your application has specific needs, let us know so we can integrate them:

• Fail-Last Position:

  • Requirement: On signal failure, the valve must stay in its current position (not open or close).

  • Solution: Add a Lock-up Valve.

• Fast Acting / Quick Exhaust:

  • Requirement: The valve moves too slowly and needs an instant response.

  • Solution: Add a Quick Exhaust Valve to bypass the positioner for rapid venting.

• "Three Failures" Protection (Extreme Safety):

  • Requirement: The process is highly critical and needs protection against loss of air, power, and signal.

  • Solution: A combination of Lock-up Valve + Quick Exhaust Valve + Signal Interrupt Module.

Specification PDF Download Link: [SONGO Specification Sheet Of Diaphragm Type Pneumatic Actuator .pdf], the specification document will help you visualize the products as we go through the selection process.