Best Flow Meters for Chlorine Gas Measurement: A Complete Selection Guide

Chlorine gas (Cl₂) is a highly reactive, corrosive, and toxic substance widely used in chemical processing, water treatment, and pharmaceuticals. However, its variable density, liquefaction risk, and safety concerns make accurate flow measurement extremely challenging.

Choosing the right chlorine gas flow meter is critical for maintaining system integrity and operator safety. This guide explores the most suitable flow meter technologies based on application needs, media characteristics, and operational conditions.
 

✅ 1. Thermal Mass Flow Meter

Why It's Recommended

• Measures mass flow directly, unaffected by pressure or temperature changes

• High accuracy: ±1% to ±2.5%

• No moving parts; available in corrosion-resistant materials like Hastelloy or tantalum

• Capable of measuring ultra-low flows (0.1 SCCM to 1000 SLPM)

Application Scenarios

• Electronic-grade chlorine monitoring

• Semiconductor manufacturing

• Chlorine cylinder flow control

⚠️ Points to Note

• Ensure chlorine stays in gaseous form; avoid liquid entry into sensor

• Use gas dryers or filters with moist chlorine to prevent probe corrosion

Learn more: What Is a Thermal Mass Flow Meter and How Does It Work?
 

✅ 2. Coriolis Mass Flow Meter

Why It's Recommended

• Highest accuracy: ±0.1% to ±0.5%

• Simultaneous measurement of mass flow, density, and temperature

• Fully metallic design (e.g., 316L stainless steel, Hastelloy), resistant to corrosion and high pressure

Application Scenarios

• Chlorine distribution in chemical plants

• Liquefied chlorine gas metering (requires insulation to prevent crystallization)

⚠️ Points to Note

• Higher cost compared to other technologies

• Difficult installation for pipe sizes > DN100

✅ 3. Differential Pressure Flow Meter (Orifice/Wedge Type)

Why It's Recommended

• Simple structure, suitable for large-diameter pipes (e.g., DN200 and above)

• Handles high pressure and aggressive gases

• Material customization: PTFE-lined bodies + Monel alloys for corrosion resistance

Application Scenarios

• Chlor-alkali industry

• Sodium hypochlorite production in large-scale water treatment plants

⚠️ Points to Note

• Requires differential pressure transmitter + temperature & pressure compensation for accuracy

• Generates significant pressure loss, increasing energy consumption

✅ 4. Vortex Flow Meter (For Dry Chlorine Only)

Why It's Recommended

• Cost-effective with a wide flow range (2–60 m/s)

• Non-contact sensing reduces corrosion risk

• Minimal maintenance, suitable for mid-range industrial applications

Application Scenarios

• Dry chlorine gas transport

• Auxiliary monitoring in air separation units

⚠️ Points to Note

• Strictly for dry chlorine; moisture leads to corrosion and signal distortion

• Accuracy decreases at low flow rates (<2 m/s)

Explore more: How Does a Vortex Flow Meter Work?
 

❌ Flow Meters Not Recommended for Chlorine Gas

Avoid flow meters made with:

• Copper or brass components – prone to oxidation and safety hazards

• Non-degreased materials or oiled tools – risk of chemical reaction or explosion

Chlorine Flow Meter Comparison Table

Safety Tips for Chlorine Gas Measurement

• Sealing: Use PTFE or Viton gaskets to prevent chlorine leaks

• Material Choice: Prefer Hastelloy C276, tantalum, or PTFE linings

• Avoid Liquefaction: Maintain pipe temperature above 10°C to keep chlorine in gaseous form

• Degreasing: All sensor surfaces must be oil-free; clean tools are mandatory

Conclusion

Measuring chlorine gas flow safely and accurately depends on the right choice of flow meter.

• For high-accuracy and multi-parameter monitoring, go with the Coriolis flow meter

• For cost-effective, corrosion-resistant measurement, the thermal mass flow meter is ideal

• For large-diameter industrial lines, differential pressure meters offer rugged performance

• For dry gas applications, consider the vortex flow meter

Always prioritize material compatibility, pressure resistance, and safety certification when working with chlorine.