Rosemount 8732E Magnetic Flowmeter 38:1 Turndown 10.5-35V DC

The Rosemount 8732E is a full-bore, two-wire magnetic flowmeter (magmeter) engineered by Emerson for highly accurate and reliable volumetric flow measurement of conductive liquids across a vast spectrum of industrial process applications. As a member of the respected Rosemount 8700 series, the 8732E model distinguishes itself by offering the performance and diagnostic capabilities of a traditional four-wire magmeter but within an innovative and efficient two-wire platform. This design significantly reduces installation costs and complexity while providing the trusted measurement principles that have made magnetic flowmeters a cornerstone of process instrumentation in industries ranging from water and wastewater to chemical processing and power generation.

The 8732E operates on the foundational principle of Faraday's Law of Electromagnetic Induction. The flowmeter consists of a flow tube, through which the process liquid passes, and a set of electrodes that sense the generated voltage. Inside the flow tube, an electromagnetic coil is energized, creating a magnetic field perpendicular to the direction of flow. According to Faraday's Law, as a conductive liquid moves through this magnetic field, it generates a voltage proportional to its velocity. The electrodes mounted on the inside wall of the liner detect this minute voltage signal. The transmitter, which is integrally mounted on the flow tube, then processes this signal, calculating the flow velocity and converting it into a precise volumetric flow rate. A key advantage of this design is that the measurement is unaffected by changes in the liquid's temperature, density, viscosity, or pressure, provided the liquid has minimal electrical conductivity (typically >5 μS/cm).

The most prominent feature of the Rosemount 8732E is its two-wire operation. Unlike traditional four-wire magmeters that require a separate power cable, the 8732E receives its operating power and transmits its output signal over the same standard two-wire 4-20 mA loop used by pressure and temperature transmitters. This dramatically simplifies installation by eliminating the need for dedicated AC or DC power runs to each meter, reducing wiring, conduit, and labor costs. Despite this, it delivers performance on par with its four-wire counterparts.

The device is equipped with the powerful Heartbeat Technology™, an embedded diagnostics suite that provides unparalleled verification of meter health and performance. Heartbeat Technology performs continuous, on-demand verification without requiring process interruption. It can detect issues such as electrode coating, liner damage, wiring problems, and changes in the fluid's conductivity, enabling predictive maintenance and ensuring measurement confidence. This capability is crucial for custody transfer applications and for processes where accuracy is non-negotiable.

Furthermore, the 8732E is designed for exceptional durability and versatility. It is available with a variety of liner materials (including PFA, ceramic, and polyurethane) and electrode materials (such as 316L SS, Hastelloy C, and titanium) to handle abrasive, corrosive, or erosive fluids. Its robust construction ensures reliable performance in demanding environments, and it offers multiple output options, including the standard 4-20 mA analog signal with overlayed HART® protocol or FOUNDATION™ Fieldbus digital communication for seamless integration into modern control architectures.

The Rosemount 8732E is suited for a wide array of applications where reliable flow measurement is critical:

• Water & Wastewater: Accurate measurement of potable water, raw sewage, treated effluent, and sludge.

• Chemical Industry: Handling of corrosive acids, caustics, and abrasive slurries.

• Power Generation: Flow measurement of cooling water, lime slurry, and flue gas desulfurization (FGD) reagents.

• Pulp & Paper: Monitoring black liquor, green liquor, and other process chemicals.

• Food & Beverage: Hygienic measurement of ingredients, concentrates, and CIP (Clean-in-Place) fluids.

In summary, the Rosemount 8732E represents a significant advancement in flowmeter technology. It successfully combines the reduced installation costs and simplicity of a two-wire system with the high accuracy, advanced diagnostics, and robust construction expected from a top-tier magnetic flowmeter. By providing trustworthy data and insights into meter health, it empowers plants to optimize their processes, improve efficiency, reduce maintenance costs, and ensure the integrity of their most critical flow measurements.