Gammapilot FMG50

Summary

Product identification

• Product Name: Gammapilot FMG50
• Type: Compact transmitter for non-contact measurement through vessel walls

Application

• Level, interface, density, concentration, and point level measurement.
• Measurement in liquids, solids, suspensions, or sludges.
• Use under extreme process conditions (high pressure, high temperature, corrosion, abrasion, viscosity, toxicity).
• Suitable for all kinds of process vessels, e.g., reactors, autoclaves, separators, acid tanks, cyclones.

Benefits

• Compact transmitter with loop-powered two-wire technology.
• Multifunctional for all measuring tasks.
• Safety compliance with SIL2 approval according to IEC 61508, and SIL 3 with redundancy.
• Heartbeat Technology for process verification without interruption.
• Various detector materials for optimal adaptation.
• Bluetooth® wireless technology for commissioning, operation, and maintenance via SmartBlue app (iOS/Android).
• Gamma Modulator FHG65 for reliable suppression of interference radiation.
• 316L stainless steel housing for heavy-duty applications.

Measuring principle

The radiometric measuring principle relies on the attenuation of gamma radiation as it passes through a material. This principle is applied to various measurements:

• Continuous level measurement: Source and detector on opposite sides of a vessel; more medium means more absorption, less radiation received.
• Point level measurement: Similar setup; radiation is typically absorbed if the path is covered by medium, indicating the level limit.
• Density measurement: Source and detector on opposite sides of a pipe; denser medium means more absorption, less radiation received.
• Concentration measurement: Indirectly via density measurement, using linearization to assign concentration values.
• Concentration measurement with radiating media: Detector measures radiation emitted by the medium itself, no external source needed.
• Interface measurement: Determines the position of the interface layer based on the density of the media.
• Measurement of mass flow (solids): Radiation is attenuated by material on a conveyor belt; mass flow is calculated from belt speed and radiation intensity.

Measuring System Components

A typical radiometric measuring system includes:

• Gamma radiation source: Typically 137Cs or 60Co, with various activities available.
• Source container: Directs radiation in one direction and shields it otherwise. Available in different sizes and beam angles.
• Gammapilot FMG50: Contains a scintillator, photomultiplier, and electronic evaluation unit. Converts incident gamma radiation into electrical pulses.
• Gamma Modulator FHG65 (optional): Rotates to alternately screen and allow the gamma beam, separating the useful signal from interference radiation.

Signal analysis

• Level measurement: Linearization function converts measured values to length or volume. Preprogrammed or user-defined linearization tables (up to 32 value pairs).
• Density measurement: Calibration uses up to four samples of known density to automatically calculate absorption coefficient and linearization curve.
• Concentration measurement: Uses a linearization table (up to 32 "density - concentration" pairs).
• Concentration measurement with radiating media: Calculates concentration from the intensity of radiation emitted by the medium.
• Mass flow measurement (liquids): Density signal from FMG50 combined with volume flow from a flowmeter (e.g., Promag 55S).
• Mass flow measurement (solids): Radiation intensity on conveyor belts is proportional to density; mass flow calculated from belt speed and intensity.
• General functions:
  • Decay compensation: Automatically compensates for the decrease in radiation source activity.
  • Gammagraphy detection: Detects short-term interference radiation and can switch off evaluation if necessary.

System integration

Integration is possible via:

• HART protocol
• Service interface (CDI) using Commubox FXA291 and DeviceCare/FieldCare.
• WirelessHART adapter (SWA70) with Commubox FXA195 and FieldCare.
• Bluetooth LE and SmartBlue App.
• Local operation.

Input variables

• Measured variable: Pulse rate (number of pulses per second), proportional to radiation intensity. This is converted to point level, level, interface position, density, or concentration.
  • Max. pulse rate: 60000 cnt/s
• Sensitivity: Pulse rate per unit dose rate or concentration. Depends on scintillator type, measuring range, and isotope.
  • NaI (Tl) scintillator (typical):
    • ¹³⁷Cs: 675 [(cnt/s)/(µSv/h)] per "inch"
    • ⁶⁰Co: 450 [(cnt/s)/(µSv/h)] per "inch"
    • K₂O: 10 [(cnt/s)/%K₂O] per "inch"
  • PVT scintillator (standard) (typical):
    • ¹³⁷Cs: 10 [(cnt/s)/(µSv/h)] per "mm"
    • ⁶⁰Co: 5 [(cnt/s)/(µSv/h)] per "mm"
  • PVT scintillator (high-temperature) (typical):
    • ¹³⁷Cs: 8 [(cnt/s)/(µSv/h)] per "mm"
    • ⁶⁰Co: 4 [(cnt/s)/(µSv/h)] per "mm"
• Typical pulse rates:
  • Level (empty vessel): ~2500 cnt/s for ¹³⁷Cs, ~5000 cnt/s for ⁶⁰Co
  • Point level (free path): ~500 cnt/s for ¹³⁷Cs, ~1000 cnt/s for ⁶⁰Co
  • Density, concentration, interface, mass flow: ~5000 cnt/s for ¹³⁷Cs, ~5000 cnt/s for ⁶⁰Co

Measuring range

• Level measurement: Typically depends on vessel height; scintillator longer than the measuring range. Multiple units can be used for ranges >4.5 m (14.76 ft).
• Point level measurement: Highly localized, smaller than the FMG50 diameter (< 85 mm / 3.35 in).
• Density measurement: Defined by the minimum and maximum density of the medium.
• Interface measurement: Determined by the possible positions of the interface (0% to 100%).
• Concentration measurement (with source/radiation source): Defined by minimum and maximum concentration.
• Concentration measurement (radiating media): Defined by minimum and maximum concentration.
• Mass flow measurement: Considered a density measurement; range defined by minimum and maximum medium density.

Output variables

• Output signal: 4 to 20 mA with HART protocol.
  • Operating modes: 4.0 to 20.5 mA, NAMUR NE043 (3.8 to 20.5 mA), US mode (3.9 to 20.8 mA).
• Error signal: Indicated on display (symbol, code, description) and via current output (MAX/MIN values).
• Load: Max. 500 Ω, Min. 250 Ω for HART communication.
• Output damping: User-definable from 0 to 999.9 s.

Power supply

• Supply voltage:
  • Non-Ex: 14 to 35 VDC
  • Ex-i: 14 to 30 VDC
  • For Bluetooth communication: 14 V or higher.
  • For display background lighting: ≥ 16 V.
  • Measurement function guaranteed from 12 V (Bluetooth not possible).
• Power consumption: < 0.81 W
• Overvoltage category: II
• Pollution degree: II
• Protection class: Class 1
• Potential equalization: Device must be included in the local potential equalization system.

Electrical connection

• Connection compartment: Standard compartment for wiring.
• 4 to 20 mA HART connection: Standard connection for HART communication and power. A HART resistor (typically 250 Ω) is necessary for low-impedance power supplies.
• Terminal assignment: Terminals for positive, negative, and internal ground.
• Cable entries: Various options available (M20, G1/2, NPT1/2 threads; M12, HAN7D plugs) with different IP ratings.
• Potential equalization: Connect potential matching line to the ground terminal.
• Overvoltage protection (optional): Nominal DC voltage 600 V, nominal discharge current 10 kA.
• Rated cross-section: > 1 mm² for protective ground/shielding; 0.5 mm² to 2.5 mm² for connecting cables.
• Fieldbus connector: Available in some versions for easier connection.
• M12-A connector: Pin assignment specified for Signal +/- and Ground.
• Harting plug Han7D: Connection details provided.

FMG50 with RIA15

• The RIA15 remote indicator can be ordered as an accessory.
• It is loop-powered and does not require external power.
• Voltage drop considerations: ≤1 V (standard), ≤1.9 V (HART), +2.9 V (display light).
• HART communication resistor module can be installed in RIA15.

Wiring

• General precautions include switching off voltage, connecting potential equalization, and using adequately insulated and temperature-stable cables.
• Wiring examples:
  • Point level measurement: Output signal can be evaluated directly or via switching units like RTA421 or RMA42.
  • Cascade mode with 2 FMG50 units: Can be interconnected and powered via one RMA42. Individual output currents are added.
  • Cascade mode with >2 FMG50 units: Can be interconnected via Memograph M RSG45 (max. 20 units). Pulse rates are added and linearized.

Disclaimer

This summary is based on extracted text and may not capture all details, figures, footnotes, or revisions. Contractual data must be confirmed against the specific OEM PDF revision used for the project.

Official datasheet (PDF)

Lenntech datasheet mirror