Endress+Hauser Prosonic S FMU90 Ultrasonic Level and Flow Transmitter

Overview of the Endress+Hauser Prosonic S FMU90

The Endress+Hauser Prosonic S FMU90 is a separate transmitter for one or two ultrasonic sensors of the FDU9x family. It measures the level of liquids and bulk solids with ranges of up to 45 m (148 ft), calculates flow in open channels and weirs, and controls pumps and rakes through up to six relays. The device is built around a six-line plain-text display with a choice of 15 languages, and it shows the envelope curve on site, so technicians can check echo quality without a laptop. Integration into control systems is done through 4–20 mA with HART or through PROFIBUS DP.

Seven Star LLC supplies the Endress+Hauser Prosonic S FMU90 with its FDU sensors to municipal and industrial water operators, wastewater contractors and bulk material handlers across the Sultanate of Oman and the GCC, with engineering support in Muscat. The transmitter is particularly common in pumping stations and treatment plants, where one unit handles level measurement, flow calculation and pump control at the same time.

Measuring Principle of the Endress+Hauser Prosonic S FMU90

The sensor connected to the Endress+Hauser Prosonic S FMU90 transmits ultrasonic pulses toward the surface of the medium, where they are reflected and received again by the same sensor. The transmitter measures the time t between transmission and reception and calculates the distance from the sensor membrane to the surface as D = c · t / 2, where c is the sonic velocity. Level is derived from this distance, and through linearization the transmitter converts level into volume, mass or, in flumes and weirs, into flow.

Because sonic velocity changes with air temperature, the transmitter applies a temperature-dependent time-of-flight correction using the sensors integrated in the FDU probes, or an external Pt100 for heated FDU90 and FDU91 sensors. Interference echo suppression maps fixed reflections from edges, welds and internal fixtures so they are not mistaken for the level echo. Each sensor has a blocking distance near the membrane, from 0.07 m for the FDU90 up to 0.9 m for the long-range FDU95, which must be considered when the sensor height is planned.

Engineering Design of the Endress+Hauser Prosonic S FMU90

The transmitter is offered in a polycarbonate field housing (IP66 / NEMA 4X, about 1.6 to 1.8 kg), an aluminium field housing (IP66 / NEMA 4X, about 6 kg, optionally with ATEX II 3D approval) and a DIN rail housing for cabinets, with an optional remote display for mounting in a cabinet door. The power supply is either 90 to 253 V AC or 10.5 to 32 V DC, and power supply, sensor inputs, analog outputs, relays and the fieldbus are galvanically isolated from one another.

Inputs and outputs are selected in the order code: one or two sensor inputs, one or two active analog outputs (4–20 mA with HART on output 1, or 0–20 mA), one, three or six SPDT relays rated 4 A at 250 V AC, an optional PROFIBUS DP interface up to 12 Mbaud, four inputs for external point level switches and an input for an external temperature sensor. The Endress+Hauser Prosonic S FMU90 recognises the connected FDU9x sensor automatically and still supports older FDU8x sensors for existing installations.

Key Features of the Endress+Hauser Prosonic S FMU90

The following capabilities, documented in TI00397F, make the Endress+Hauser Prosonic S FMU90 a standard solution for water and wastewater duties:

• Level and point level measurement of liquids and bulk solids with ranges up to 45 m, depending on the FDU sensor.
• Pre-programmed flow curves for Khafagi-Venturi, ISO and BST Venturi, Parshall and Palmer-Bowlus flumes and for rectangular, trapezoidal and triangular weirs.
• Up to three totalizers and three daily counters, with counting and time pulses for samplers and external units.
• Alternating pump control or control by pump rate, with individual switching delays and backlash times per pump.
• Optional advanced pump control with standby pump, storm function, flush control, tariff control and pump function test.
• Average, difference and sum calculation from two sensors, including rake control in screens.
• Backwater and dirt detection in flumes, and alarms for echo loss.
• Measured error of ±2 mm + 0.17 % of measured distance, with 1 mm resolution for FDU90 and FDU91 sensors.

Industrial Applications of the Endress+Hauser Prosonic S FMU90

Typical installations of the Endress+Hauser Prosonic S FMU90 include wet wells and lift stations with up to six pumps, inlet channels and Parshall flumes at sewage treatment works, stormwater overflow basins where level and discharge are measured with one sensor, screen channels with differential rake control, reservoirs, and silos or conveyor belts in the bulk solids industry. In Oman these duties are found in municipal sewage networks and treatment plants in Muscat, treated effluent and irrigation channels, industrial wastewater at the Sohar and Salalah free zones, and cement and aggregate plants.

Seven Star LLC supplies the transmitter together with the matching FDU sensor, mounting brackets and protective covers for outdoor installations in strong sunlight. For complete water and wastewater measuring points, buyers can add the Endress+Hauser Micropilot FMR20 radar, the Promag W 10 electromagnetic flowmeter for closed pipes, or the Liquiline CM442 multiparameter transmitter for analysis.

Technical Specifications of the Endress+Hauser Prosonic S FMU90

Key data of the Endress+Hauser Prosonic S FMU90 from Technical Information TI00397F are listed below.

How to Order

To order the Endress+Hauser Prosonic S FMU90, send Seven Star LLC the application (level, flow or pump control), measuring range, number of sensors, relays and outputs, power supply and housing, and our instrumentation division will return a formal quotation with the matching FDU sensor and lead time. Technical Information TI00397F can be downloaded from this page. Seven Star LLC is a trusted supplier of Endress+Hauser level products in Oman and the GCC, with engineering support in Muscat for configuration and start-up.