Views: 50 Author: Site Editor Publish Time: 2025-08-01 Origin: Site
Selecting the right thermal mass flow meter requires careful analysis of your application’s gas type, flow range, and operating conditions. Below is a structured guide to ensure optimal performance and cost-effectiveness:
1. Key Selection Criteria
(1) Gas Composition
Compatible Gases | Best for clean, dry gases(air, N₂, O₂, CO₂, natural gas). |
Avoid dirty/wet gases(require filters), corrosive gases (e.g., HCl) unless they use specialty coatings (Hastelloy). | |
Calibration | Must be calibrated for the specific gas (accuracy degrades if used for uncalibrated gases). |
(2) Flow Range & Pipe Size
Turndown Ratio | Standard: 100:1(e.g., 0.1~10 m/s for air). |
High-end: Up to 1000:1 (for wide dynamic ranges). | |
Pipe Diameter | Insertion probes: DN50–DN6000. |
Inline models: DN2–DN50(small pipes). |
3) Process Conditions
Parameter | Typical Range | Notes |
Temperature | -40°C to +200°C | High-temp versions up to 450°C |
Pressure | Up to 100 Bar | Check pressure rating of seals |
Humidity | <90%RH (non-condensing) | Moisture requires heated probes |
2. Sensor Technology Options
Type | Principle | Best For |
Constant Power | Measures cooling effect | Low-flow gases (0.01–5 m/s) |
Constant ΔT | Maintains temp difference | High-flow(5~100 m/s), faster response |
3. Output & Communication
Analog | 4–20mA, 0–10V (for PLC integration). |
Digital | Modbus, HART, PROFIBUS(smart factories). |
4. Mechanical Design
Feature | Options | Selection Tip |
Probe Type | Insertion, inline | Insertion for large pipes (>DN100) |
Material | 316SS, Hastelloy, PTFE | Corrosive gases → Hastelloy C276 |
Protection | IP65, IP67, Ex-d (explosion-proof | Hazardous areas require ATEX/IECEx |
5. Accuracy & Calibration
Standard Accuracy | ±1–2% of reading (±0.5% for high-end models). |
Calibration | Lab-calibrated(NIST-traceable) for critical applications. |
Field-calibrated (with bypass) for maintenance ease. |
6. Cost Considerations
Entry-level | $1,000–$3,000 (basic air/N₂ applications). |
High-performance | $5,000–$15,000 (corrosive gases, high accuracy). |
7. Decision Checklist
1 | Confirm gas type and purity. |
2 | Define min/max flow rates and pipe size. |
3 | Verify temperature/pressure limits. |
4 | Choose probe material(match gas compatibility). |
5 | Select output/communication protocol. |
6 | Check certifications (ATEX, SIL2 if needed). |
For dirty gases, add an upstream filter.
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