Absolute pressure transmitters are used in industrial applications where it is essential to measure absolute pressure without any dependence on variations in atmospheric conditions.
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The FKA and FKH high-precision absolute pressure transmitter models accurately measure absolute pressure and transmit a proportional 4-20 mA electrical output signal. The transmitter uses a unique, highly reliable micro-capacitive silicon sensor, combined with state-of-the-art digital signal processing to deliver outstanding performance in terms of accuracy and stability.
Absolute pressure transmitters measure the process pressure of atmospheric air, other gases, vapors and liquids relative to the reference point of absolute zero, i.e. a perfect vacuum. All pressure transmitter takes measurements relative to a reference pressure. These pressure transmitters operate using the pressure of perfect vacuum (absolute zero) as a reference.
A total vacuum corresponds to an absolute pressure of 0 bar, and the average barometric pressure at sea level is 1013.25 mbar. On the other hand, sensors that quantify the difference between process pressures and atmospheric pressure are called gauge pressure transducers. Differential pressure transmitters, on the other hand, measure two opposing pressures.
The intelligent FCX industrialpressure transmitter calculates and measures pressure by changing the deformation of a metal diaphragm.
The low-pressure side of the sensor is subjected to an absolute vacuum, then sealed.
As a result, the measured diaphragm deformation is unaffected by external pressure and serves as a zero point for the closed vacuum envelope.
As these pressure transmitters are not affected by variations in atmospheric pressure, their measurement is more accurate than relative pressure transmitters (for normal applications).
They also have high repeatability and long-term stability.
HIGH REPEATABILITY
LONG-TERM STABILITY
These pressure transmitters are generally more expensive than gauge pressure transmitters. Another disadvantage of this type of sensor is its much lower maximum pressure capacity than that of relative digital pressure transmitters . They require special tools to calibrate, and can often take longer.
You can ask our instrument calibration service team to help you with this task.
The unit of measurement for absolute pressure is indicated by the letter 'a' or the abbreviation 'abs' (i.e. bar (abs), H₂O (abs), psia or kPa (abs)).
They range from vacuum to several bars, with excellent long-term stability.
The maximum operating pressures they can measure vary.
In many cases, they can measure pressures as high as 30 bar (abs) with excellent accuracy and stability.
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 measurements are accurate, and that a fixed vacuum pressure (absolute zero) is used as a reference.
This ensures that your processes are free from fluctuations in atmospheric pressure.
This type of sensor is the only device capable of measuring atmospheric pressure, so it can be used to assess barometric pressure.
Altitude calculation based on atmospheric pressure variation during altitude changes is another example of its use.
Changes in temperature, pressure and humidity all affect atmospheric pressure.
Atmospheric pressure can fluctuate by around 30 mbar due to weather changes, and by around 200 mbar if the sensor altitude changes.
Consequently, for the same measured pressure, a digital pressure gauge may provide a measurement error due to variations in atmospheric pressure.
When measuring low pressure, this error can be significant.
In this case, the use of an absolute pressure transmitter is recommended.
A typical application is measuring the liquid level of water, which can be found using a gauge pressure sensor in open (i.e. non-pressurized) tanks.
Liquid raw materials are stored, and the tank is freely ventilated above the liquid. The hydrostatic pressure of the liquid column is used to calculate the volume.
For low-height tanks, levels can fluctuate significantly over time due to ambient air pressure influencing both sensor readings and tank ventilation, resulting in the calculation of an incorrect liquid level. It is important to choose an absolute pressure transmitter to ensure accurate measurement.
