Prosonic S FDU91

Summary

Product identification

• Product Name: Prosonic S FDU91
• Type: Ultrasonic sensor for level measurement and flow measurement
• Manufacturer: Endress+Hauser
• Document: TI01470F/00/EN/02.21

Application

• Continuous, non-contact level measurement of liquids and bulk solids in silos, on conveyor belts, in material stockpiles and in crushers.
• Flow measurement in open flumes and measuring weirs.

Operating limits

• Maximum measuring range: 10 m (33 ft) in liquids; 5 m (16 ft) in bulk solids.
• Process temperature: –40 to +80 °C (–40 to +176 °F).
• Process pressure: 0.7 to 4 bar (10.15 to 58 psi).

Input

• Blocking distance: 0.3 m (1.0 ft). Signals within this range cannot be measured.
• Operating frequency: 43 kHz.

Measurement principle

The sensor transmits ultrasonic pulses that reflect off the medium's surface. The transmitter measures the time between transmission and reception to calculate the distance to the surface. This distance, along with the sonic velocity, is used to determine the level or flow.

Temperature-dependent time-of-flight correction

An integrated temperature sensor corrects for time-of-flight variations due to temperature changes. For versions with an integrated sensor heater (FDU91-**B), an external temperature sensor (Pt100 or Omnigrad S TR61) is required.

Electrical

• Supply voltage: Provided by the transmitter (FMU90 or FMU95).
• **Sensor heater power supply (for FDU91-B):
  • Supply voltage: 24 VDC ± 10 %
  • Residual ripple: < 100 mV
  • Current consumption: 250 mA per sensor
  • Suitable power supply unit: RNB130 from Endress+Hauser.
• Extension cable specifications:
  • Maximum total length (sensor cable + extension cable): 300 m (984 ft).
  • Cross-section: 0.75 to 2.5 mm² (18 to 14 AWG).
  • Resistance: Max. 8 Ω per wire.
  • Capacitance, wire to shield: Max. 60 nF.

Mechanical / hydraulic

• Dimensions: See graphical representation in the document.
• Weight (including 5 m cable): Approx. 1.1 kg (2.43 lb).
• Materials:
  • Sensor housing: PVDF
  • Counter nut: PA6.6
  • Connecting cable: PVC
• Process connection: G 1" or NPT 1" (depending on version).
• Degree of protection: IP68 / NEMA6P (tested according to 24 h at 1.83 m (6 ft) under water).
• Vibration resistance: DIN EN 600068-2-64; 1 (m/s²)/Hz; 3x100 min.
• Thermal shock resistance: Based on DIN EN 60068-2-14.
• Electromagnetic compatibility: Meets EN 61326 series and NAMUR Recommendation EMC (NE 21) for industrial environments.

Installation

• Level measurement:
  • Recommended distance to vessel wall: 1/6 of the vessel diameter.
  • Avoid mounting in the center or through filling curtains.
  • Ensure no internal fixtures are in the signal beam.
  • For bulk solids, use the FAU40 alignment unit to ensure perpendicularity to the surface.
  • Emitting angle (typical): 9°.
• Flow measurement:
  • Mount on the upstream side above the maximum upstream level (Hmax) plus blocking distance.
  • Position in the center of the channel or weir.
  • Align perpendicular to the water surface.
  • Observe mounting distance to flume constriction or weir edge.
  • Protect from sun and precipitation with a weather protection cover.
• Nozzle mounting: Smooth interior, no edges or welds, beveled nozzle end on tank side (ideally 45°). Maximum nozzle lengths are specified for different nozzle diameters (DN80/3" to DN300/12").
• Ultrasound guide pipe: Minimum diameter DN100, venting hole at the top, keep clean.

Certificates and approvals

• CE mark
• RoHS
• RCM-Tick marking
• Ex approval (available, see Product Configurator)

Accessories

• Sensor extension cable (max. 300 m total length)
• Weather protection cover
• Screw-in flange FAX50
• Cantilever arm for sensors (available in 500 mm and 1000 mm lengths)
• Mounting bracket for ceiling mounting
• FAU40 alignment unit
• RNB130 power supply unit for sensor heater
• IP66 protective housing for RNB130 power supply unit

Disclaimer

This summary is based on extracted text from an OEM PDF datasheet. The extraction may have missed figures, footnotes, or specific revision details. Contractual technical data must always be verified against the official OEM PDF revision used for the project.

Official datasheet (PDF)

Lenntech datasheet mirror