Optimizing pressure transmitters calibration interval involves adjusting them according to the accuracy required, the Total Probable Error (TPE) and the sensor's stability. By calculating these elements, calibrations can be spaced out without compromising compliance or performance, thus reducing maintenance costs.
Determining the pressure transmitters calibration period is a complex decision influenced by many factors. Each industrial site must define its own calibration frequencies, based on historical performance and specific process requirements.
This article focuses on determining the optimum calibration intervals for pressure transmitters in order to save time and money.
It presents a five-step process for calculating an estimated calibration interval, taking into account factors such as required in-service performance, operating conditions,Total Probable Error (TPE ) and stabilitydatasheet .
High-performance transmitters enable these calibration cycles to be extended, reducing maintenance costs and offsetting the initial purchase price.
The ultimate aim is toalign pressure transmitters calibration practices with the actual stability and performance of modern pressure measurement technologies.
We offer a 5-step process for estimating the calibration interval from available publisheddatasheet and application data:
This is the expected instrument accuracy, typically ±0.5% to ±2% of the calibrated range.
This accuracy takes into account the effect of ambient temperature, the effect of static pressure and all the factors that influence the accuracy of pressure measurement.
It varies according to the level of criticality:
Variations in ambient temperature and static pressure at the point of measurement must be taken into account.
It combines the uncertainties associated with :
The calculation uses the quadratic method:
TPE = ± √((E1)² + (E2)² + (E3)²)
Our article How to calculate the accuracy of a pressure transmitter and what is Total Probable Error? enables you to calculate the Total Probable Error (TPE) needed to determine the optimum calibration frequency for pressure transmitters.
Expressed as a percentage of maximum scale (URL) over several years.
Sensor stability varies according to performance class.
Example: Fuji Electric Series AIX-V6 FKC = ±0.1% of the URL over 10 years.
Formula: Interval = (Required performance - TPE) / Stability
All units must be consistent.
If the result exceeds the maximum range defined by stability, this limit prevails.
Here's an example of how to calculate the calibration frequency of a Fuji Electric pressure transmitter using the 5-step approach described above.
Let's start by determining the installed performance required for the application
Industrial application requirement: The pressure transmitter must provide an installed performance of ± 0.5% of the set measuring range.
Operating conditions: The device will read a differential pressure of 100 mbar under normal operating conditions.
Conversion: The required maximum permissible tolerance (TMA) of ± 0.5% of the 100 mbar range results in a required installed performance of ± 0.5 mbar.
Now let's define the operating conditions
Let's calculate theTotal Probable Error (TPE) using the Fuji Electric FKC high-performance FCX AIV-6 series differential pressure transmitter as an example.
A sensor with an upper scale limit (URL) of 320 mbar offers sufficient flexibility to handle variations in measured differential pressure in many industrial applications. The necessary performance datasheet are available in the Fuji FKC data sheet.
By combining these uncertainties using the quadratic method, we obtain a :
Applied to a measurement range of 100 mbar, this gives :
Identify the Fuji Electric FKCstability datasheet - FCX-AIV-6 series
The stability datasheet for this high-performance transmitter is ± 0.1% of the URL over 10 years (equivalent to the best market standards, by way of example).
Let's now calculate thecalibration frequencyof the Fuji Electric FCX pressure transmitter using the following formula:
Interval = (0.5 mbar-0.179 mbar) / 0.00267 mbar/month = 120 months
The estimated calibration period for the Fuji Electric FKC - FCX-AIV-6 transmitter, in this application (100 mbar range, accuracy required ± 0.5%), is approximately: 120 months, or 10 years without loss of accuracy and without zero adjustment.
The aim is to define a calibration interval that meets the needs of the industrial installation, while complying with current regulations.
Comparing estimated intervals with calibration results under real conditions provides a solid basis for adjusting frequencies and taking advantage of the stability and performance of modern transducers such as Fuji Electric's new AIV-V6 series pressure transmitters .
High-performance FCX AIV-6 series pressure transmitters can operate reliably for a decade without recalibration, under stable conditions.
Making the right choices when it comes to pressure transmitters and calibration intervals, with the help of an expert, is essential for optimizing your processes and obtaining the best results.
Improve the reliability of your measurements, reduce maintenance costs and control your risks by entrusting the calibration of your pressure transmitters to our specialists.
Fuji Electric's calibration services offer calibration on site or in our calibration laboratory.
Our reference standards are verified by an accredited organization, guaranteeing you reliable results and the measurement accuracy of your instruments.
Our technicians are equipped with test equipment, pressure sources and HART communicators for regular maintenance of your sensors.
At Fuji Electric France, our experts use proven scientific methods that take into account drift data, your maximum permissible tolerances (MPT) and the criticality of each measuring point to dynamically adapt calibration intervals to your real needs.
Our services cover all types of instruments, Fuji Electric or third-party, and enable you to :
