Choosing the right Coriolis mass flow meter doesn’t have to be complicated. Emerson’s Micro Motion brand is the industry benchmark, with the widest product line and largest market share. By systematically answering a few key questions, you can easily find the perfect model for your application.
1. Before You Start: Define Your Application Profile
Before diving into product catalogs, answer these five core questions:
- What are you measuring? – Liquid, gas, or slurry? Corrosive? High viscosity? Any sanitary requirements?
- What are the process conditions? – Normal operating temperature? Pipe pressure? Maximum and normal flow rates? Pipe size?
- What is the installation environment? – Hazardous area or a clean workshop? Any space constraints?
- What level of accuracy is needed? – For custody transfer or internal process control?
- What certifications are required? – Hazardous area, sanitary, SIL, custody transfer approvals?
Answering these will instantly narrow down your options.
2. Why Choose Emerson Micro Motion?
Emerson Micro Motion meters work on the Coriolis principle. As fluid flows through vibrating tubes, the generated Coriolis force causes a phase shift, which is directly proportional to mass flow. Compared to traditional volumetric meters, the key advantages are:
- High Accuracy: Up to ±0.1%–±0.2% of rate, with repeatability better than ±0.1%.
- Multi-Variable Output: Simultaneously measures mass flow, density, and temperature (and optionally viscosity) from a single device.
- Immunity to Fluid Properties: Changes in density, viscosity, and temperature have minimal impact on accuracy.
- No Straight Pipe Runs Required: Flexible installation that saves valuable space.
- Fast Response: High-frequency signal processing for millisecond-level response, ideal for fast-changing processes.
3. Key Sizing Parameters Explained
1. Flow Range: Finding the Sweet Spot
The “nominal flow rate” is defined by Micro Motion as the flow at a roughly 1 bar (14.5 psig) pressure drop with water.
- Your normal operating flow should fall within 30% to 70% of the meter’s capacity.
- Ensure the meter’s turndown ratio covers both your minimum and maximum flows.
- Velocity is generally controlled between 0.5 and 12 m/s.
Pro Tip: Use the official Emerson Flow Sizing & Selection Tool to simulate pressure drop and flow rates with your actual parameters.
2. Accuracy Grade: Fit for Purpose
Don’t over-specify; match accuracy to the application:
| Application | Recommended Accuracy | Notes |
|---|---|---|
| Custody Transfer | ±0.1%–±0.2% (or Class 0.2) | Legal metrology required for buy/sell |
| Critical Process Control | ±0.1% (High-precision series) | e.g., precision batching, reaction control |
| General Process Monitoring | ±0.5% (Class 0.5) | Standard process variable tracking |
| Flow Indication | ±1.0% | Trend monitoring only |
3. Fluid Compatibility: Choosing Wetted Materials
Wetted parts must be compatible with your process fluid. Here are the standard options:
| Material | Suitable For | Unsuitable For | Typical Application |
|---|---|---|---|
| 316L Stainless Steel | Water, weak acids/bases, solvents, food-grade | Strong corrosive acids/bases | General chemical, water, food & bev |
| Hastelloy C | Mixed acids, oxidizing salts (e.g., seawater) | Hydrochloric acid | Offshore, chemical anti-corrosion |
| Tantalum | HCl (<40%), Sulfuric acid, Nitric acid | Alkalis, Hydrofluoric acid | Strong acid measurement |
| Titanium | Chlorides, alkaline solutions (<50%) | Reducing acids (HCl, H2SO4) | Seawater, chloride systems |
4. Temperature & Pressure
- Standard sensors: -100°C to 204°C. High-temperature models up to 350°C are optional.
- For extreme temperatures (e.g., LNG), select specialized cryogenic models.
- Pressure ratings vary by model and size (e.g., ELITE series can reach 99.97–124.93 barg).
5. Pressure Drop: A Critical Check
Coriolis meters cause a pressure drop, which must be within your process allowance. This is influenced by flow rate, density, viscosity, and pipe diameter. Use the online sizing tool to verify this automatically.
6. Output & Communication
Choose based on your control system:
- Analog: 4-20 mA (standard, with HART)
- Pulse/Frequency: For totalization
- Digital: Modbus RTU/RS-485, PROFIBUS-DP/PA, FOUNDATION Fieldbus, EtherNet/IP, PROFINET
- Wireless: WirelessHART, Bluetooth® (supported by 5700 transmitter)
4. Sensor Series Selection
1. ELITE Series — Flagship Performance
The pinnacle of accuracy and stability, with line sizes from 1/4” to 16” (DN6–DN400) and density accuracy up to ±0.0005 g/cm³. Designed for the most demanding applications. Best for: Custody transfer, high-precision batching, and critical loops.
2. F Series — Compact & Precise
High-accuracy in a compact, self-draining design. Covers line sizes from 1/4” to 3” (DN6–DN80), with standard accuracy of ±0.10% (optional ±0.05%). Best for: Critical process control where space is tight.
3. G Series — Ultra-Compact & Easy
Among the most compact dual-tube meters, with face-to-face dimensions under 30 cm for the DN25 sensor. Pre-configured models make selection very easy. Best for: Process monitoring, skids with extreme space constraints.
4. H Series — The Sanitary Benchmark
Purpose-built for hygienic applications. 316L stainless steel with a 15 Ra surface finish, meeting 3-A and EHEDG standards for CIP/SIP processes. Best for: Food & beverage, pharmaceutical, biotech.
5. R Series — General Purpose Value
Compact, self-draining, and provides reliable flow and density measurement at a competitive price. Best for: General applications where budget is a key factor.
6. T Series — Straight-Tube Corrosion Expert
Features a titanium wetted part with a single, straight tube that can be self-drained, pigged, and cleaned in place. Best for: Chemical anti-corrosion, food, and applications prone to clogging.
7. TA Series — For Extreme Corrosion
Made with pure tantalum, this series is designed exclusively for highly corrosive acids and alkalis. Best for: Batching and distribution of extreme chemicals.
5. Transmitter Selection
The transmitter processes the sensor signal. Key models include:
- 5700: Flagship field/mount transmitter with advanced diagnostics, Smart Meter Verification, and Bluetooth®.
- 4700: Compact C1D1 design with 1–3 configurable I/O channels.
- 4200: 2-wire design, sharing power and signal on the same pair of wires.
- 2400S: Ultra-compact integral mount for tight spaces.
- 1700/2700: Classic field-mount with analog and HART.
6. Installation Requirements
- Orientation: Tubes down for liquids, tubes up for gas, flag-mount for slurries.
- No straight pipe runs are required.
- Maintain a full pipe; install control valves downstream of the meter.
- Use isolation valves and pipe supports to minimize stress.
- Avoid strong electromagnetic fields.
7. Certification Checklist
Ensure your selected model has the necessary certifications:
- Hazardous Area: ATEX, IECEx, CSA/FM, NEPSI
- Sanitary: 3-A, EHEDG
- Custody Transfer: OIML R 117, MID, NTEP
- Safety (SIL): SIL2/SIL3 (available on 1700/2700 transmitters)
Selection Roadmap: A 7-Step Summary
- Define Fluid Properties: Name, corrosiveness, viscosity, particle content.
- Set Flow Range: Max/normal/min flow, ensuring normal flow is in the 30-70% sweet spot.
- Determine Accuracy: Custody (0.1-0.2%) vs. process (0.5%) vs. indication (1.0%).
- Choose Wetted Material: Match with 316L, Hastelloy, Tantalum, or Titanium.
- Pick a Sensor Series: Select from ELITE, F, G, H, R, T, or TA based on your priority.
- Select a Transmitter: Match I/O, protocol, and installation needs.
- Finalize Installation & Certs: Confirm orientation, environmental limits, and mandatory certifications.
For final validation, use the official Emerson Flow Sizing & Selection Tool or contact us at Yinkor for a free technical double-check.