Introducing the working principle of scraper flowmeters—save this now!

The scraper flowmeter is an effective positive-displacement flowmeter designed to measure the volumetric flow rate of fluids in a closed-system pipeline. It is primarily used for measuring heavy oils such as crude oil. The scraper flowmeter features on-site display of cumulative flow and includes a remote transmission output interface. It can be paired with compatible photoelectric pulse converters and totalizing flow computers to enable remote measurement, display, and control functions.

The scraper flowmeter not only boasts high accuracy, excellent repeatability, and a wide measurement range, but also requires minimal straight pipe sections both upstream and downstream of the meter. It is ideally suited for clean, non-corrosive fluids—and equally effective with high-viscosity fluids such as crude oil, petroleum, solvents, chemical raw materials, paints, and lubricants. Moreover, the fluid’s viscosity has negligible impact on the meter’s indicated value.

How does a scraper flowmeter work? Let’s all take a quick look at it together below.

The scraper of the scraper flowmeter is driven by the fluid to rotate a rotor system. During rotation, the scraper alternately extends and retracts under the action of a fixed cam, continuously creating discrete volumes of fluid within the metering chamber. Since the volume of each metering chamber remains constant, the number of rotations of the rotor directly corresponds to the amount of fluid flowing through the meter. Finally, a reduction mechanism in the counter accurately scales up these fluid volumes for precise measurement.

The main chamber of the scraper flowmeter, along with its gear assembly, precision corrector, and instrument, consists primarily of key components such as a rotor, cam, camshaft, connecting rod, rollers, cover plate, and housing. The inner cavity of the housing is a circular, hollow cylinder. The rotor itself is a rotating, thin-walled, hollow cylinder. We utilize two pairs of scrapers, with four pairs arranged in a cross-shaped configuration.

When the scraper flowmeter is operating, the scraper shaft rotates, causing the four scrapers to extend and retract one by one. At no point does a fixed space form between the cavity and the scrapers. Instead, the verification fluid sequentially fills each of the four scrapers, creating four identical measurement chambers, each with a precisely defined volume. This volume is then converted by a gear mechanism and transmitted to the meter head. Finally, the counter on the meter head translates the number of rotations into the actual measured volume, which is recorded accordingly—thus achieving the purpose of quantifying the medium being measured. Additionally, after calibration is complete, the pulse signal output system of the meter can be used to input the calibrated instrument coefficient into the computer connected to the meter. By integrating this data into the corresponding management software, the system ensures accurate display of the flowmeter’s volumetric flow rate.

There are many scraper flowmeters available on the market—so, what key factors should educators pay attention to when making their selection? Let’s take a quick look at this together below.

1. The manufacturer’s technical expertise. When selecting a scraper flowmeter, it’s crucial to pay close attention to the manufacturer—specifically, whether they have successfully mastered these technological advancements or if the company already offers a product that is particularly representative of its capabilities. If such a product exists, it’s a strong indicator that the manufacturer is reliable and trustworthy, allowing you to purchase with confidence.

II. Specific Design Parameters of the Equipment. When selecting a scraper flowmeter, companies need to pay close attention to the flowmeter itself. It’s essential to understand how the flowmeter’s parameters are set under different conditions, how these parameter settings evolve over time, and whether they remain appropriately optimized. This knowledge will significantly enhance our ability to use the device effectively in the future—so make sure to keep a keen eye on these factors.

3. User Reviews. If you’re unfamiliar with scraper flowmeters—or haven’t had the chance to use one yet—be sure to pay close attention to user feedback on these devices.