Absolute pressure transmitters are used in applications where it is critical to measure absolute pressures without any dependence on changes in barometric conditions.
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.
Accurate measuring results independent of atmospheric conditions
Significant process performance thank to 4D GyrationTM characterization
High plant availability thanks to high reliability unique design
Technical Features
High accuracy and reliability
Minimum inventory and design
Minimal environmental influence
HART communication protocols with local operator interface
Application flexibility
Programmable output Linearization function
Long-term stability
What is the principle of absolute pressure transmitter?
Absolute pressure transmitters measure the process pressure relative to atmospheric air, other gases, steams 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 transmitters. Differential pressure transmitters, on the other hand, measures two opposing pressures.
How the absolute pressure transmitter work ?
The intelligent pressure transmitter industrial FCX 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 pressure transmitters (for normal applications). They also have high repeatability and long-term stability.
HIGH REPEATABILITY
LONG-TERM STABILITY
What are the cons of absolute pressure transmitter ?
These pressure transmitters are generally more expensive than gauge pressure transmitters. Another disadvantage of this type of sensor is that its maximum pressure capacity is much lower than that of digital gauge pressure transmitters. They require special tools to be calibrated and can often take longer.
What is the unit of the absolute pressure transmitters ?
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 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.
What are the fields of application of absolute pressure transmitters?
In general, they are capable of measuring the pressure of any gas or fluid under pressure.
These pressure transmitters are used in the chemical and petrochemical industries, the food industry, the metallurgical industry, the oil and gas industry , and in research laboratories and 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.
measuring the level of low-lying storage tanks
monitoring of gas pipeline pressure measurement
barometric pressure measurement
Why using an absolute pressure transmitter versus gauge pressure transmitter ?
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.
A typical application is measuring the level of liquid that can be found using a gauge 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.
Don't be stymied by atmospheric conditions and opt for absolute pressure transmitter performance!
