Selecting an industrial gas proportional valve (modulating valve) is critical for achieving stable combustion control, accurate fuel-air ratio, and safety in a gas train. Here’s a practical, engineering-focused guide:

1. Define Your Application Requirements

Start with the operating conditions:

• Fuel type: Natural gas, LPG, biogas, etc. (affects material compatibility and Cv sizing)

• Flow rate range:

  • Minimum flow (turndown)

  • Maximum flow (full load)

• Control objective:

  • Pressure control

  • Flow control

  • Air–gas ratio control (common in burners)

• Response time:

  • Fast (process heating, ovens)

  • Moderate (boilers)

2. Flow Capacity (Cv / Kv Sizing)

This is the most critical parameter.

• Calculate required Cv (or Kv) based on:

  • Inlet pressure (P1)

  • Outlet pressure (P2)

  • Gas type and temperature

  • Maximum flow rate

👉 Rule of thumb:

• Choose a valve where normal operating flow is 30–70% of max Cv

• Avoid oversizing → leads to unstable control and poor modulation

3. Pressure Range & Control Type

Inlet Pressure Range

• Ensure compatibility with upstream regulator

• Typical: 20 mbar – several bar

Control Mode

• Proportional (analog):

  • 0–10 V

  • 4–20 mA (industry standard)

• Closed-loop capable (with controller):

  • For precise combustion systems

4. Turndown Ratio (Modulation Range)

• Defines how well the valve handles low fire vs high fire

• Typical values:

  • 5:1 → basic systems

  • 10:1 or higher → high-performance burners

👉 Higher turndown = better energy efficiency and flame stability

5. Response & Accuracy

• Fast response → better flame control

• Hysteresis & repeatability:

  • Look for ≤ ±1–2% for precision systems

6. Safety & Certifications (VERY IMPORTANT)

For industrial gas systems (especially in Europe):

• EN 161 (automatic shut-off valves)

• EN 88 / EN 126 (pressure regulators, if integrated)

• CE certification

• SIL / IEC 61508 (if required for safety systems)

👉 Often proportional valves are used together with safety shut-off valves

7. Valve Type & Design

Common types:

a) Proportional Solenoid Valve

• Fast response

• Compact

• Good for small–وسطة systems

b) Motorized Control Valve

• Higher precision

• Better for large flow / high pressure

• Slower but more stable

c) Butterfly + Actuator

• For large pipelines

• Cost-effective at high flow

8. Material & Gas Compatibility

• Aluminum, brass, or stainless steel

• Check compatibility for:

  • Biogas (corrosion, H₂S)

  • LPG (sealing materials)

9. Electrical & Control Integration

• Input signal: 0–10 V or 4–20 mA

• Feedback signal (optional): position feedback

• Power supply: 24 VDC / 230 VAC

10. Environmental Conditions

• Ambient temperature range

• IP protection (IP54, IP65…)

• Hazardous area (ATEX if needed)

11. Typical Brands (Industrial Standard)

• Siemens (VGG / VGF series)

• Dungs

• Honeywell (Kromschröder)

• Bosch Thermotechnology

• ASCO

12. Simple Selection Workflow

1. Define gas type + max flow

2. Calculate required Cv/Kv

3. Confirm pressure range (P1, P2)

4. Choose control signal (4–20 mA recommended)

5. Check turndown ratio

6. Verify certifications (CE, EN 161, etc.)

7. Match pipe size & connection

8. Ensure compatibility with burner control system

13. Common Mistakes to Avoid

• Oversized valve → unstable flame

• Ignoring minimum controllable flow

• No safety shut-off valve in system

• Wrong signal type (mismatch with PLC)

• Ignoring pressure drop

• Phone: +86 185 6630 3837
  WhatsApp: +86 185 66303837
  Email: ekelairn@gmail.com
  Web.: http://ekgas.com