DLT 12400 Digital Level Transmitter

With a combination of features such as smart filtering, HART® communication protocol compatibility and an optional 4-20 mA analog output signal, Baker Hughes Masoneilan 12400 Series transmitter/controller offers exceptional process control for a wide range of applications - even severe service. Easy to install and operate, it is the first torque tube-type level instrument that integrates level transmitter and switch functions in a single device. Plus, the 12400 Series transmitter/controller is engineered for optimum efficiency, upgradeability and reliability making it a cost-effective investment for the long term.

The Masoneilan 12400 Series instrument is a two-wire, loop-powered level transmitter with HART® Communication that operates according to the fully proven buoyancy and torque tube principles. A change in liquid level varies the net weight of the displacer (2), increasing or decreasing the load on the torque tube (4) by an amount directly proportional to the change in liquid level. The resulting rotation of the torque rod (6) and attached magnets (7) modifies the magnetic field surrounding a non-contact sensor (8), producing an analog signal proportional to the level in the vessel. This analog signal is converted into an error-free digital signal that is processed by the on-board micro-controller. After processing, the digital result is converted to a 4-20 mA analog output signal. This sensing method is non-contacting and frictionless, and it provides total isolation between the sensed motion and sensor output.

Main Mechanical Sub-Assemblies

Four Main Mechanical S/A :
⦁ Displacer Chamber with its displacer S/A
⦁ Mechanical Chamber
⦁ Torque Tube S/A
⦁ Instrument Head

Level vs Interface Measurement

⦁ Level Measurement: one single liquid
⦁ Interface Measurement : Measurement of interface position between two non-miscible liquids

Level Measurement

⦁ Measurement of liquid quantity : %, volume, - height
⦁ Only one liquid
⦁ Above the liquid - gas (steam)
⦁ Displacer movement much smaller than level variation
⦁ Fluid Specific Gravity – Standard Displacer
     ⦁ Calibrated in Water
     ⦁ SG = 0.15 to 1.4
     ⦁ Custom displacer for other ranges

Interface Measurement

⦁ Measurement of interface position between two non-miscible liquids
⦁ Upper fluid always is the lower S.G.
⦁ Displacer movement much smaller than Interface level variation
⦁ Above the upper fluid is gas (steam)
⦁ Minimum S.G. difference between the two liquids: 0.15 (with standard displacer)

Archimedes' Principal

A body wholly or partially immersed in a fluid is buoyed up by a force equal to the weight of the liquid displaced. Weight of the liquid displaced varies with the shape of the object and is more in case of float. Displacer cross sectional area is uniform.

Non-contact Sensor Technology

⦁ Non-contact Hall Effect magnetic sensor
⦁ Measurement of magnetic field variations
⦁ Wide process temperature range
⦁ Software ambient temperature compensation
⦁ LCD with 3 explosion-proof push-buttons
      ⦁ 7-language LCD display
⦁ Encapsulated electronic module for Protection
      ⦁ Humidity
      ⦁ Mechanical Shock
      ⦁ Water
      ⦁ Vibration

Reference:
https://dam.bakerhughes.com/m/4a99f38aa1cda6bc/original/BHMN-12400-DLT-BR-19663D-0620-English-pdf.pdf