Flow Meters for Chemical Processing & Dosing
Precision dosing of acids, bases, solvents, and viscous chemicals. Corrosion-resistant, hazardous-area certified, and SIL-rated for safety-critical applications.
Launch Interactive SelectorChemical Processing: Precision Meets Hazard Management
Chemical processing and dosing operations demand flow metres that can survive aggressive, corrosive, and flammable fluids whilst maintaining ±0.1% batch accuracy. Whether metering concentrated sulphuric acid into a reactor, injecting polymer into a polymer blend, or dosing chlorine into a treatment tank, the margin for error is zero.
Beyond accuracy, chemical applications impose material and regulatory constraints. Corrosive fluids attack standard stainless steel and elastomers. Hazardous areas (ATEX Zone 1/2) prohibit electronic equipment without intrinsic safety certification. And safety systems (SIL 2/3) require metres with documented failure rates and proof-test intervals.
Key Industry Challenges
Chemical Compatibility
Corrosive chemicals (acids, bases, solvents) attack standard stainless steel. Hastelloy, tantalum, and PTFE/PFA linings resist most corrosives, but material selection requires careful analysis.
Hazardous Area Certification
Many chemical facilities are ATEX Zone 1 or 2 (explosive atmosphere likely/unlikely). Metres must be intrinsically safe or housed in explosion-proof enclosures. ATEX/IECEx certification is mandatory.
Precision Dosing & Batch Control
Batch recipes often tolerate ±1% ingredient variance. This requires metre accuracy better than ±0.1% and integration with DCS (distributed control systems) for real-time mass/volume control.
Wide Viscosity Range
Chemical processes range from water (1 cP) to bitumen (100,000+ cP). Volume-based metres lose accuracy with viscosity; mass-based metres are viscosity-independent.
Safety System Integration (SIL)
Critical dosing operations (e.g., caustic injection, acid-base neutralisation) may require SIL 2/SIL 3 safety functions. Metres must have documented Probability of Failure on Demand (PFD) data.
Temperature & Pressure Extremes
Reactors operate at elevated temperature/pressure. Metres must withstand design pressures (up to 40+ bar) and temperatures (up to 150+ °C) without sensor drift or lining degradation.
Recommended Flow Meter Technologies
Coriolis (Mass Flow)
Operating Range: DN6–DN50 typical
Accuracy: ±0.1% of reading (mass)
Material Options: Hastelloy, tantalum, PFA
Coriolis metres are the preferred technology for precision batch dosing. Direct mass measurement, viscosity-independent operation, and density feedback enable accurate formulation across varying ingredient viscosities.
Material selection is critical. Standard 316L stainless fails in aggressive chemicals; specify Hastelloy C-276 (resistant to most acids and salts), tantalum (strongest corrosion resistance), or PTFE/PFA linings.
Integration with DCS via 4-20 mA or Modbus enables real-time batch control and alarms for overfill/underflow.
Key Benefits: Direct mass, ±0.1% repeatability, viscosity-independent, density feedback, DCS integration.
Electromagnetic (Corrosion-Resistant Lining)
Operating Range: DN10–DN100
Accuracy: ±0.5% of reading
Pressure Drop: Negligible
Suitable for conductive chemicals (acids, bases, aqueous solutions). Material selection is essential: PTFE/PFA linings resist most corrosives; tantalum or Hastelloy electrodes for harsh environments.
Zero pressure loss and excellent turndown make electromagnetic metres ideal for injection/dosing where backpressure cannot be tolerated.
DCS-compatible with integral 4-20 mA and Modbus outputs.
Key Benefits: Zero pressure loss, turndown 20:1–40:1, low maintenance, ATEX-rated variants available.
Positive Displacement (Gear/Screw)
Operating Range: DN10–DN50
Accuracy: ±0.2–0.5% of reading
Viscosity Range: 1 cP to 50,000+ cP
Excellent for high-viscosity chemicals: resins, polymers, adhesives, bitumen. Direct volumetric measurement with no pressure drop penalty.
Gear and screw designs available; screw metres are preferred for viscous products (lower wear). Coating options (e.g., nickel, ceramic) prevent product sticking and corrosion.
Lower cost than Coriolis for simple volume dosing.
Key Benefits: High-viscosity handling, low cost, direct volume, no pressure drop.
Ultrasonic (Clamp-On)
Operating Range: DN10–DN100
Accuracy: ±1–2%
Product Contact: None
Non-invasive verification for corrosive or hazardous chemicals. No product contact eliminates material compatibility concerns. Ideal for temporary flow surveys, process troubleshooting, and compliance audits.
Accuracy is sufficient for monitoring and process verification, though not recommended for critical batch control.
Key Benefits: Non-invasive, no product contact, no safety hazard during installation.
Technology Comparison: Chemical Processing Applications
| Application | Coriolis | Electromagnetic | Positive Displacement | Ultrasonic |
|---|---|---|---|---|
| Acid/Alkali Dosing | Recommended | Recommended | Not suitable | Verification |
| Precision Batching | Recommended | Good | Fair | Not suitable |
| High-Viscosity (Resin/Polymer) | Good | Not suitable | Recommended | Not suitable |
| Solvent Dosing | Recommended | Not suitable | Fair | Verification |
| Reactor Feed | Recommended | Good | Good | N/A |
| Catalyst Metering | Recommended | Limited | Good | N/A |
| Neutralisation Control | Recommended | Recommended | Not suitable | N/A |
| Hazardous Area (ATEX Zone 1) | Limited | Recommended | Not suitable | Not suitable |
Key Specifications to Consider
Chemical Compatibility
Consult manufacturer compatibility charts for all chemicals in your process. Standard 316L stainless is insufficient for many corrosives. Hastelloy, tantalum, or PTFE/PFA linings are often required.
ATEX/IECEx Certification
If operating in hazardous areas (explosive atmosphere), ATEX 2014/34/EU certification is mandatory. Confirm category (1/2 for Zone 1/2) and EPL (equipment protection level).
Batch Accuracy (Total Measurable Uncertainty)
Chemical batch recipes often require ±1% ingredient tolerance. Metre accuracy must be better than ±0.1%. Include electronics calibration uncertainty (typically ±0.05%).
Operating Temperature & Pressure
Verify the full design envelope. Reactors can reach 150+ °C and 40+ bar. High-temperature lining/elastomer options extend range; confirm sensor stability at max. temperature.
SIL Capability (If Required)
Safety-critical dosing (e.g., neutralisation, caustic injection) may require SIL 2/3 certification. Manufacturer must provide documented Probability of Failure on Demand (PFD) and proof-test intervals.
DCS/PLC Integration
4-20 mA or Modbus RTU/TCP output required for automated batch control. Confirm data refresh rate (<1 s for real-time control) and communication timeout behaviour.
Pressure Drop & Backpressure Tolerance
Dosing systems often operate against reactor backpressure. Metre pressure drop is additional load on pump. Electromagnetic and PD metres minimise this; Coriolis metres accept 0.5–2 bar drop.
Cleaning & Maintenance Protocol
Some chemicals require special flushing procedures (e.g., solvent rinse before water). Confirm metre design allows safe cleaning without product trapping or cross-contamination.
Standards & Certifications for Chemical Processing
ATEX 2014/34/EU (Hazardous Atmospheres)
EU directive for equipment used in explosive atmospheres. Equipment must carry ATEX certification per category (1 for Zone 1, 2 for Zone 2). Metres operating in hazardous areas require either intrinsic safety (ia/ib) or flameproof enclosure.
IECEx (International Electrotechnical Commission)
Global certification for hazardous area equipment. Equivalent to ATEX in non-EU countries. Equipment certified to both ATEX and IECEx is universally recognised.
IEC 61508 (Functional Safety)
Defines SIL (Safety Integrity Level) requirements for safety-instrumented systems. If the metre is part of a critical safety function (e.g., caustic injection limit), SIL 2 or SIL 3 certification is required.
PED 2014/68/EU (Pressure Equipment Directive)
All metres rated >0.5 L/min and >0.5 bar must comply. Specifies design, manufacture, testing, and CE marking. Most chemical-grade metres fall under Module B (type-examination) at minimum.
BS EN ISO 8504 (Surface Preparation)
Defines surface preparation and coating standards for corrosion resistance. Relevant if Hastelloy or specially coated materials are specified.
Chemical Safety Management Guidance
COSHH (Control of Substances Hazardous to Health) and other UK chemical safety regulations require equipment to be fit for purpose. Metre selection must align with chemical storage/handling protocols.
Key Manufacturers for Chemical Processing
Emerson Micro Motion (Coriolis - Chemical Grade)
Elite and R-Series with Hastelloy, tantalum, or PTFE options. SIL-capable variants available. ±0.1% accuracy, density measurement, DCS integration standard. Strong in chemical processing globally.
Typical cost: £7,000–£20,000
Endress+Hauser Promass (Coriolis - Chemical Grade)
Promass X line with chemical-resistant materials. Hastelloy/PTFE options, SIL 2/3-capable, ATEX available. ±0.1% repeatability.
Typical cost: £6,500–£18,000
Yokogawa ROTAMASS (Coriolis)
Compact Coriolis with chemical-grade materials. ATEX intrinsically safe option available. ±0.1% accuracy, good for budget-conscious chemical applications.
Typical cost: £5,500–£15,000
Krohne OPTIFLUX (Electromagnetic - Chemical Grade)
Hastelloy/tantalum electrode options, PTFE/PFA linings. ATEX-certified variants available. ±0.5% accuracy, zero pressure drop.
Typical cost: £3,000–£9,000
Siemens SITRANS FM (Electromagnetic & Magnetic)
Corrosion-resistant variants with special materials. ATEX options for hazardous areas. Good integration with SIMATIC PLC/DCS.
Typical cost: £2,500–£8,500
Bürkert (Positive Displacement & Magnetic)
PD metres for high-viscosity chemicals, magnetic metres for precision dosing. Lower cost, good for non-critical applications.
Typical cost: £2,000–£7,500
Material Selection for Chemical Compatibility
Stainless Steel 316L
Suitable for: Neutral and slightly acidic aqueous solutions, mild alkalis.
Not suitable for: Strong acids (H₂SO₄, HCl), chloride solutions at elevated temperature, oxidising agents.
Hastelloy C-276
Suitable for: Most acids (H₂SO₄, HCl, HNO₃), alkalis, chloride solutions, solvents.
Not suitable for: Concentrated oxidising acids above 50 °C.
Tantalum
Suitable for: Strongest corrosion resistance. All acids, all alkalis, all solvents, hydrofluoric acid.
Limitations: Very expensive, dense, difficult to machine.
PTFE/PFA Lining
Suitable for: Most aggressive chemicals. Acid-resistant, alkali-resistant, non-wetting.
Limitations: Lower temperature than metal (typically max. 80 °C for PTFE, 120 °C for PFA). Product sticking possible with high-viscosity fluids.
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