Crude oil handover trade commonly uses scraper flowmeters.

　　As global economic development accelerates at a rapid pace, oil—as a commodity—is increasingly integrated into international trade markets. As a critical step in the import and export process of petroleum, oil measurement and handover is now receiving greater attention from industry stakeholders. The accuracy of oil measurement during trade transactions directly impacts various aspects of the economy, including supply, sales, and transportation. The scraper method, which divides the liquid volume into discrete segments for precise measurement, is currently widely used in China for measuring crude oil products.

　　The key components of the scraper steam flowmeter include the top cover, metering chamber body, camshaft, roller bearings, inner and outer housings, motor rotor assembly, scraper blade, ball bearings, gear set, differential frequency modulator (precision adjuster), counter, and display unit. After precision machining, the top cover, inner and outer housings, scraper blade, and motor rotor collectively form a metering chamber with accurately calibrated volume. As the motor rotor—mounted on the roller bearings—rotates along with the attached scraper blade, it displaces a fixed volume of fluid. This rotational motion is then transmitted via the gear set to the display unit, where the counter calculates the number of rotations based on the gear ratio and the known volume per rotation. Finally, the counter translates these rotational movements into a precise measurement of the fluid’s volume, enabling accurate volumetric calibration of the petroleum substance.

　　The steam flowmeter equipped with remote transmission water meter single-pulse input/output further converts the rotation of mechanical components into differential signals using a magneto-electric induction method. By analyzing the number of pulses generated by the steam flowmeter along with its corresponding instrument index, it accurately determines the volume of liquid being measured. The scraper-type steam flowmeter boasts high measurement accuracy and reliable metrological performance—its functionality is typically unaffected by variations in liquid conditions or flow resistance levels. Additionally, its rolling bearings and scraper mechanism are highly resistant to wear, corrosion, sand ingress, and exhibit excellent long-term reliability.

　　Factors that can affect the precision of scraper steam flowmeters include ambient temperature, fluid viscosity, instrument vibrations, and damage to the metering verification chamber. Specifically, as temperature rises, fluid viscosity decreases, leading to increased leakage; conversely, when temperatures drop, viscosity increases, reducing leakage. Meanwhile, damage to the metering verification chamber can significantly disrupt the predictable relationship between leakage rates and operating conditions, potentially causing data errors to shift in a "negative" direction. Using volumetric tubes for online calibration of scraper steam flowmeters not only enables accurate real-time verification but also ensures that it does not interfere with the oil-handling companies' critical handover measurements. Additionally, this approach helps minimize costs associated with dismantling and transporting the flowmeters, while simultaneously reducing the risk of potential damage—ultimately maximizing the company's overall economic and operational efficiency.

　　A certain metering station at the Tuha Oilfield conducted a verification of a scraper steam flowmeter used for oil measurement handover tasks, following the JJG667—2010 "Verification Regulation for Liquid Volumetric Flowmeters," using a volume pipe method. Since the initial verification results indicated a data error exceeding the steam flowmeter's own allowable tolerance, the instrument's indicated error was adjusted before undergoing a second verification. This allowed the team to assess how the measurement accuracy of the scraper steam flowmeter had improved—or deteriorated—after the adjustment.