Dual Rotor Flow Meter Solution for High-Viscosity Oil Batch Metering
Addressing the challenges of metering crude oil, heavy oil, residue and lubricants in tank farms, refineries and pipeline transfer stations - high viscosity, strong temperature sensitivity, pump-induced pulsation and strict custody-transfer accuracy - this solution uses dual rotor (double helical rotor) positive displacement flow meters with 0.2%/0.5% accuracy, 6.3MPa pressure rating, -20 to +150 degC medium range and full explosion-proof certification, integrated with gas eliminators, strainers, temperature compensation and batch controllers into a standard metering skid for automated batch loading, mass-based settlement and fully traceable custody transfer.
Overview
Summary
Addressing the challenges of metering crude oil, heavy oil, residue and lubricants in tank farms, refineries and pipeline transfer stations - high viscosity, strong temperature sensitivity, pump-induced pulsation and strict custody-transfer accuracy - this solution uses dual rotor (double helical rotor) positive displacement flow meters with 0.2%/0.5% accuracy, 6.3MPa pressure rating, -20 to +150 degC medium range and full explosion-proof certification, integrated with gas eliminators, strainers, temperature compensation and batch controllers into a standard metering skid for automated batch loading, mass-based settlement and fully traceable custody transfer.
Key Advantages
Challenges
- Crude, heavy and residual oils are highly viscous with viscosity changing sharply with temperature; velocity-type meters (turbine, vortex) drift in discharge coefficient and cannot hold 0.2% custody-transfer accuracy at low Reynolds numbers, and seasonal temperature swings make the same meter deviate differently in winter and summer
- Reciprocating and screw pumps create strong flow pulsation when transferring viscous oils; ordinary meters fluctuate and cumulative error grows batch after batch, leaving both parties disputing the data and frequent shortage claims
- Tank farm transfers and loading operations are batch-oriented; manual valve watching is inefficient, overfill and underfill cause product loss and safety hazards, and automatic batch control with interlocked shut-off is missing
- Loading racks and pump rooms are explosive atmospheres where non-certified instruments are not permitted; viscous oils often require heat tracing, and meters with insufficient medium temperature range freeze up in winter
- Volume metering and mass settlement diverge through temperature-density conversion; heavy oils have large density swings with temperature, so without compensation, volumetric delivery and mass-based settlement do not reconcile and monthly inventory gaps cannot be arbitrated
Results
- Helical-rotor positive displacement accuracy is immune to viscosity and pulsation: custody transfer holds 0.2% and internal accounting 0.5% even on crude and heavy oil, repeatability better than 1/3 of the basic error limit, and shortage disputes drop sharply
- Batch controller plus shut-off valve delivers automated preset-volume loading with two-speed interlocked cut-off; overfill and underfill are eliminated, loading time per batch is shortened, and manual valve-watching posts are removed
- Full explosion-proof certification (Ex db IIC T6 Gb / Ex tb IIIC T85 degC Db) allows deployment in tank farm loading zones and hazardous pump rooms and passes safety and fire inspections; medium temperature capability to 150 degC with heat tracing keeps lines flowing in winter
- Temperature transmitter and compensator automatically convert operating volume to standard mass, aligning supplier and customer settlement data, removing seasonal deviation, and making monthly inventory gaps explainable and traceable
- Metering data is centralized through RTU upload; batch reports, shipping ledgers and inventory accounting are generated automatically, product-loss investigation is backed by continuous data, and every tank transfer and pipeline handover is digitally recorded
Solution Details
Dual Rotor Flow Meter for High-Viscosity Oil Batch Metering
In crude oil gathering, tank farm transfer, refinery loading and finished-product pipeline custody transfer operations, the metering of crude oil, heavy oil, residue, fuel oil and high-viscosity lubricants directly determines the fairness of commercial settlement. The viscosity of these media varies dramatically with temperature: velocity-type meters such as turbine meters suffer serious discharge-coefficient drift and cannot hold accuracy at low Reynolds numbers, while reciprocating and screw pumps introduce strong flow pulsation that further amplifies metering error. The dual rotor flow meter uses a pair of helical rotors meshing at constant speed inside the measuring chamber, dividing the fluid into fixed volumes and discharging it continuously. Its accuracy is virtually unaffected by viscosity and pulsation, with low pressure loss and extremely low noise, making it the preferred positive displacement instrument for high-viscosity oil batch metering.
Built around 0.2%/0.5% accuracy classes, working pressure up to 6.3MPa and medium temperature from -20 to +150 degC, the solution integrates a gas eliminator to remove entrained gas, a strainer to protect the rotor pair, a temperature transmitter with compensator for automatic volume-to-mass conversion, and a batch controller interlocked with shut-off valves for preset-volume loading. Metering data is uploaded via RTU to the monitoring platform, which automatically generates batch reports and inventory ledgers, covering custody transfer and internal accounting for tank farms, refineries, marine terminals and pipeline stations across the full viscosity spectrum of oil products.
Key Specifications of the Dual Rotor Flow Meter Solution
0.2% / 0.5%
Accuracy Class (JJG667-2010)
6.3 MPa
Max Working Pressure
-20 to +150 °C
Medium Temperature Range
10:1 or Higher
Turndown Ratio
Ex db IIC T6 Gb
Explosion-Proof Rating
IP65
Transmitter & Counter Protection
Product Features of the Dual Rotor Flow Meter
- Positive displacement high accuracy: a pair of helical rotors turns at constant speed in the measuring chamber, dividing fluid into fixed volumes; accuracy class 0.2%/0.5% per JJG667-2010, with no accuracy degradation on viscous media
- Pulsation-resistant, low-noise operation: constant-speed meshing rotors run smoothly with minimal flow pulsation and stable output pulses, reliable even on reciprocating pumps, with extremely low field noise
- Wide temperature and pressure range: medium -20 to +150 degC, working pressure up to 6.3MPa, turndown 10:1 or higher, covering the full viscosity spectrum from crude to fuel oil to lubricants
- Explosion-proof construction: field remote display rated Ex db IIC T6 Gb / Ex tb IIIC T85 degC Db, transmitter and counter IP65, ready for tank farm loading zones and hazardous pump rooms
- Flexible signal outputs: pulse, 4-20mA and RS485 options compatible with batch controllers, PLC and RTU networks, with configurable counters, governors and external fine adjusters
- Standard metering skid integration: supplied as a set with gas eliminator, strainer, temperature compensator and batch controller; flanges per GB/T9113.1-2000; wetted materials in cast iron, cast steel or stainless steel selected per medium
Applications of the Dual Rotor Flow Meter in Oil Custody Transfer
The dual rotor flow meter solution is engineered for crude oil gathering, tank farm transfer, refinery loading and finished-product pipeline custody transfer. It delivers reliable batch metering across the full viscosity spectrum of oil products, from light crude to heavy residue and high-viscosity lubricants.
Integrated with a gas eliminator, strainer, temperature compensator and batch controller, the system supports preset-volume loading with interlocked shut-off valves. Metering data is uploaded via RTU to the monitoring platform, which automatically generates batch reports and inventory ledgers, covering custody transfer and internal accounting for tank farms, refineries, marine terminals and pipeline stations.
? References
- JJG667-2010 — Verification Regulation for Positive Displacement Flow Meters
- GB/T9113.1-2000 — Flange Standards for Pipeline Systems
- Ex db IIC T6 Gb / Ex tb IIIC T85 degC Db — Explosion-Proof Certification Standards
Approach
How we implement intelligence into your infrastructure step by step.
Process survey and accuracy class definition
Review oil products, viscosity-temperature curves, batch flow ranges, working pressures and pump types (reciprocating/screw/centrifugal); define 0.2% custody-transfer or 0.5% internal-accounting accuracy, hazardous-area classification and heat-tracing needs, and produce the metering point list and selection basis.
Sizing and metering skid configuration
Select dual rotor meter size and accuracy class from viscosity and batch flow; integrate gas eliminator, strainer, temperature transmitter with compensator for volume-to-mass conversion, and batch controller interlocked with shut-off valves into a standard loading skid.
Installation with heat tracing and Ex protection
Install horizontally with bypass and proving connections; add heat tracing and insulation for viscous, congealing oils; complete cable entries, sealing and grounding per explosion-proof codes in hazardous areas; arrange straight runs and gas eliminator position where pump pulsation is severe.
Calibration, verification and batch commissioning
Verify factory wet-calibration certificates and submit to legal metrology for periodic verification per JJG667-2010; configure batch presets, two-speed cut-off logic and deviation alarms in the batch controller, then commission across tank-transfer, loading and pipeline-handover duties.
Data networking and periodic maintenance
Upload pulse/RS485 signals via RTU to the monitoring platform for automatic batch reports, shipping ledgers and inventory accounting; establish rotor wear inspection, strainer cleaning, gas eliminator venting and periodic verification schedules to keep custody-transfer values trustworthy long term.
❓ Related FAQs
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