Micro Motion FDM Specifications

Micro Motion® Fork Density Meters

Direct insertion density meter

Product Data Sheet

PS-001485, Rev F

November 2018

Rugged, accurate density and concentration measurement

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Continuous, real-time measurement in pipelines, bypass loops and tanks

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Accurate measurement of density (±1 kg/m3) and concentration (±0.1%)

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Wide range of corrosion-resistant materials for aggressive liquid measurement

Superior multi-variable I/O, meter health, and application capabilities

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Hazardous-area approved, head-mounted transmitter that supports local configuration and display

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Internal diagnostics for fast verification of meter health and installation

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Application-specific factory configurations ensure fit-for-purpose operation

Installation flexibility and compatibility

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Optimized design – insensitive to vibration, temperature and pressure variations

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Unique direct insertion design in lengths of up to 13 ft (4 m)

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Supports multiple protocols for connection to DCS, PLC, and flow computers

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Optional stainless steel transmitter housing for corrosion resistance in harsh environments

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Fork Density Meter

November 2018

Micro Motion Fork Density Meters

Micro Motion Fork Density Meters provide precision liquid density measurement in tank and pipeline applications. The Fork Density
Meters use vibrating fork technology to measure density directly, and can be used in process control where density is the primary
control parameter for the end product or as an indicator of another quality control parameter, such as %solids or %concentration.

Application configurations

Integral HART I/O direct input of external temperature, pressure, and flow measurements provide enhanced readings.

Integral transmitter

Supports Time Period Signal (TPS), Analog (4-20 mA), HART, WirelessHART®, Modbus RS-485 and FOUNDATION™ fieldbus
communications.

Meter diagnostics

Ensure measurement health through known density verification (KDV) and other meter and installation diagnostic capabilities.

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Power, RS-485
2 x mA Outputs...

Power, RS-485
2 x mA Outputs...

HART
WirelessHART

FOUNDATION
fieldbus

Fork Density Meter

Compatible Devices

Mass Flow

Net solids flow

Full API

Enhanced
concentration
accuracy

Temperature

Magnetic flow Pressure

November 2018

Fork Density Meter

Retrofit capabilities

Full backwards compatibility provides the same form and fit as the Micro Motion 7826/7828 direct insertion density meters.

Interconnectivity

Integral HART I/O allows direct input of external temperature, pressure, and flow measurements for enhanced measurements.

ProLink® III software: a configuration and service tool

ProLink III software is an easy-to-use interface that allows you to view key process variables and diagnostics data for your meter. For
more information on ordering the software, contact your local sales representative or email customer support at

[e-mail].

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Fork Density Meter

Operating principle

Fork vibration

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A fully welded fork assembly is mounted directly into the liquid to be measured.

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The fork tines are vibrated piezo-electrically at its natural frequency.

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The tines' natural frequency changes with the density of the surrounding liquid.

A. Integral transmitter with optional local operator interface
B. Process connection
C. Vibrating tines

D. RTD measures temperature

November 2018

Temperature measurement

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An integral class “B” RTD measures the vibrating fork temperature.

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Micro Motion transmitters use this reading to optimize performance over a wide range of process conditions.

Density calibration

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Micro Motion transmitters accurately measure time period.

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Measured time periods are converted into density readings using meter calibration coefficients.

A. Density (kg/m3)
B. Time period = 1 / frequency
C. [Time period]2 (μs2)

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November 2018 Fork Density Meter

Performance specifications

Density measurement

Specification Value

Accuracy

Operating density range

(1)

(2)

±1 kg/m

0 to 3000 kg/m

Repeatability ±0.1 kg/m

Process viscosity effect

(3)

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Process temperature effect (corrected)

(4)

±0.1 kg/m3 per °C ±0.0001 g/cm3 per °C

Process pressure effect (corrected) None

Stated accuracy is for calibrated range 600–1250 kg/m3 (0.6–1.25 g/cm3). Accuracy can be affected by the liquid viscosity. See the product

(1)

configuration manual for more detail on entering an offset for the effects.
The viscosity of the liquid can be up to a maximum of 500 cP.

(2)

For viscosities between 200–500 cP, the process viscosity effect increases with the viscosity up to a maximum of ±19 kg/m3 (±0.019 g/cm3). This

(3)

effect can be significantly reduced by performing an onsite calibration. Viscosity effect shown is for long tine (FDM1). For short tine (FDM2), no
effect for 0-100 cP and reduced effect for 100-500 cP.
Temperature effect is the maximum measurement offset due to process fluid temperature changing away from the factory calibration

(4)

temperature.

3

3

3

No effect for 0–50 cP
±4 kg/m3 (±0.004 g/cm3) for 50–200 cP

±0.001 g/cm

0 to 3.0 g/cm

±0.0001 g/cm

3

3

3

Temperature measurement

Specification

Operating temperature range – short
stem

Operating temperature range – long
stem

Integral temperature measurement

Value

–50 °C to +200 °C –58 °F to +392 °F

–40 °C to +150 °C –40 °F to +302 °F

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Technology: 100 Ω RTD

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Accuracy: BS1904 Class, DIN 43760 Class B

Pressure ratings

Actual maximum operating pressures are limited by the process connection rating. For Zirconium flanges, the maximum operating
pressure is dependent on the working temperature.

Specification

Maximum operating pressure – short stem

(1)

Maximum operating pressure – long stem 1,450 psi (100 bar)

Test pressure Tested to 1.5 times the maximum operating pressure

PED compliance Not applicable

Value

3,000 psi (207 bar)

For short-stem meters with a cone seat fitting, the maximum operating pressure is 1,450 psi (100 bar)

(1)

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Fork Density Meter November 2018

Transmitter specifications

Available transmitter versions

For more information on the transmitter outputs and ordering codes, see the Ordering information section.

Analog

Typical application Output channels

A B C

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General purpose measurement

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DCS/PLC connection

Processor for remote-mount Model 2700 FOUNDATION fieldbus transmitter

Typical application Output channels

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General purpose measurement

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DCS/PLC connection

4–20 mA + HART
(passive)

A B C

Disabled Disabled Modbus/RS-485

4–20 mA (passive) Modbus/RS-485

Discrete

Typical application

A B C

Flow Computer/Signal Converter connection 4–20 mA + HART

(passive)

Time Period Signal (TPS)

Typical application

A B C

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General purpose measurement with output
switch

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DCS/PLC connection

4–20 mA + HART
(passive)

Output channels

Discrete output Modbus/RS-485

Output channels

Time Period Signal (TPS) Modbus/RS-485

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