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Absolute pressure transmitter

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Absolute pressure transmitters are used in applications where it is critical to measure absolute pressures without any dependence on changes in barometric conditions.


Benefits of the absolute pressure transmitter FCXAbsolute pressure transmitter FCX

The FKA high accuracy absolute pressure transmitter model and FKH high accuracy absolute pressure transmitter model accurately measure an absolute pressure and transmits a proportional 4-20 mA output signal.

The transmitter uses a unique high reliability micro-capacitive silicon sensor in combination with a state-of-the-art digital signal processing to provide exceptional performances in terms of accuracy and stability.

  • Short delivery time (Made in France)
  • Accurate measuring results independent of atmospheric conditions
  • Significant process performance thank to 4D Gyration TM characterization
  • High plant availability thanks to high reliability unique design

Technical benefits

  1. High accuracy and reliability
  2. Minimum inventory and design
  3. Minimum environmental influence
  4. HART communication protocols
  5. Application flexibility
  6. Programmable output Linearization function
  7. Burnout current flexibility
  8. Long term stability

 


What is the principle of absolute pressure transmitter?

What is the unit of the absolute pressure transmitters

Absolute pressure transmitters measure the process pressure relative to atmospheric air, other gases, vapors and liquids from the absolute zero reference point, i.e., perfect vacuum.
Any pressure transmitter takes measurements against a reference pressure.
In case of absolute sensors, they work using perfect vacuum pressure (absolute zero) as the reference.

A full vacuum has an absolute pressure reading of 0 bar and average barometric pressure at sea level is 1013,25 mbar.

In contrast, the transmitters that quantify the difference between the process pressures against barometric pressure are called gauge pressure sensorsThe differential pressure transmitters, on the other hand, measures two opposing pressures.

 

 


How the absolute pressure transmitter work ?

Why using an absolute pressure transmitter versus gage pressure transmitter

FCX Smart industrial pressure transmitter calculates the pressure by the deformation change of a metal diaphragm.
The low-pressure side of the sensor is subjected to an absolute vacuum and then sealed.

As a consequence, the measured deformation of the diaphragm is unaffected by external pressure and serves as the zero point for the closed vacuum envelope.


What are the advantages of absolute pressure transmitter?

Because absolute pressure transmitters are not affected by changes in barometric pressure, they are more accurate than gauge types (for normal applications).
They also have a high repeatability and long term stability.

 

high repeatability and long term stability
 


What are the cons of absolute pressure transmitter ?

What are the cons of absolute pressure transmitter 0

  • They are typically more expensive than gauge pressure transmitters.
  • Another disadvantage of this type is much lower maximum pressure capability compared to digital pressure gauge sensors.
  • They require special tools to calibrate them and can often take more time.
    You need to ask our instruments' calibration service team to support for this task.

What is the unit of the absolute pressure transmitters ?

All absolute pressure measurements are positive.
The unit of absolute pressure measure is indicated by the 'a' letter or the ‘abs’ abbreviation (i.e., in bar (abs), inH₂O (abs), psia or kPa(abs)).

 

What is the unit of the absolute pressure transmitters (2)

 


What are the pressure ranges for absolute pressure transmitters ?

What are the pressure ranges for absolute pressure transmitters

Their range can go from the vacuum to several bars with long term stability.
The maximum working pressures that they can measure varies.
In many cases, they can measure pressures as high as 30 bar (abs) with excellent accuracy and stability.


Where are absolute pressure transmitters used?

Where are absolute pressure transmitters used

Absolute pressure transmitters are used in applications where it is critical to measure absolute pressures without any dependence on changes in barometric conditions.
Typically, they are capable of measuring pressure in any pressurized gasses or fluids.

Absolute pressure sensors are used in the chemical and petrochemical industries, food industries, metal processing, oil and gas industries, laboratory and research institutes.
For these industrial applications, it is imperative that the measurements are accurate and to use a fixed vacuum pressure (absolute zero) as the reference.
Your processes are thus free of atmospheric pressure fluctuations.

An absolute pressure sensor is the only device that can measure atmospheric pressure, so it may be utilized to assess barometric pressure.
The calculation of altitude based on the variation in atmospheric pressure when the elevation changes is another example of how this may be utilized.

Typical applications

  • measuring the level of low-lying storage tanks
  • monitoring of gas pipeline pressure measurement
  • barometric pressure measurement

Why using an absolute pressure transmitter versus gage pressure transmitter ?

Why choosing the Fuji Electric absolute pressure transmitter FCX series

Changes in temperature, pressure, and humidity all affect the barometric pressure.
The atmosphere's pressure can fluctuate by about 30 mbar due to weather changes, and by about 200 mbar if the sensor's elevation changes.
As a result, for the same measured pressure, a digital pressure gauge may provide a measurement error owing to atmospheric pressure variations.
When measuring low pressures, this error could be significant.

In such a case, the use of an absolute pressure sensor is recommended.

One typical application is for the water liquid level measurement that can be found using a relative pressure sensor in open (i.e., non-pressurized) tanks.
Raw material liquids are stored, and the tank is freely vented above the liquid, the hydrostatic pressure of the liquid column is used to calculate the volume.

For low height tanks, levels could fluctuate significantly over time owing to ambient air pressure influencing both sensor readings and the vessel's ventilation, resulting in an incorrect liquid level being calculated.

It is important to choose for absolute pressure sensors to guarantee accurate measurement.