Tolerance of calibration gas
To be a calibration gas, the gas must be traceable to a national or international standard. Traceability is an unbroken chain of traces that can be compared to an internationally accepted standard. The standard calibration gas is an established concentration of a known chemical component to be analyzed. In calibration gases, preparation tolerance (PT) and certification/analytical accuracy (CA) are extremely important.
Tolerance is the concentration range of one or more minor components in a mixture. PT is measured over a concentration range. It can also be called blend tolerance. For example, a calibration gas of 500 ppm CO balanced in nitrogen, has a PT of +/- 10%. This calibration gas will contain between 450 ppm and 550 ppm CO in Nitrogen. Standard tolerances can be minimized by using the latest technologies in the production of such gases. Standard tolerances are determined based on the manufacturer’s experience and customer requirements.
Tiêu chuẩn khí hiệu chuẩn là gì
Calibration gas standards must be expressed by mass. And confirmed by the supplier using a laboratory chromatograph. The calibration gas composition must approximate the normal composition field.
The calibration gas must be heated for at least 24 hours to 140°F. To ensure that the gas is single phase and homogeneous. To ensure proper sample mixing, the temperature difference between the top and bottom of the cylinder is limited to 10°F. Calibration gas should be replaced annually. Or replace when cylinder pressure drops below 50% of original pressure value. Or cylinder pressure drops below 50 psig. Whichever is lower.
What is calibration?
Calibration is the activity of determining and establishing the relationship between a measurement standard and a measuring instrument. To evaluate errors and its other technical and measurement characteristics. Calibration is not mandatory. Based on the calibration results, customers decide whether to use the device again or not.
The role of calibration
+ Maintain the values of the standard system as well as the system of measuring instruments being used. Their alignment with measurement standards ensures consistency and accuracy of measurement.
+ Determine the error of the measuring instrument. From there, adjust the measuring device to suit the measurements.
+ Ensure the reliability of measuring equipment for measurement results.
+ Determine the measurement uncertainty of the measuring instrument.
+ Helps detect failures or predict failures. From there, there is a plan to repair the measuring devices.
+ Conforms to industry, national and international quality standards.
What is the application of calibration gas?
Any measuring device needs to be recalibrated after a period of time. Due to many reasons such as: Changes in components, changes in the usage environment, contamination from the measurement environment… Particularly for gas meters and gas analysis instruments, calibration is even more necessary than for most sensors. The transformer operates according to electrochemical principles, the chemical composition will change after each measurement, or change itself due to natural chemical reactions.
- Standard gas is used to calibrate gas analyzers, gas meters or calibrate fixed gas detectors.
- Special calibration gases calibrate gas meters and cylinders in the marine, hygiene and health sectors.
