Pressure Gauge Calibration
Basically, there are two types of pressure calibration standards: primary and secondary standards. A primary pressure standard is an instrument that measures or generates pressure which can reduce those pressure measurements into measurements of mass, length, temperature, and gravity. Examples are dead weight testers and mercury manometers. A secondary standard is an instrument, which must be calibrated to relate the output to pressure. Both standards have advantages and disadvantages discussed below.
To respond to the need for accurate, fast, easy-to-use instrument calibration, a complete pressure gauge calibration system has been developed to work as the secondary standard. The system can calibrate both analog gauges and manual gauges using either absolute pressure reference or differential pressure reference.
The working medium can be either liquid or gas. For the pneumatic system, the working range is from a vacuum up to 6,000 psi. For the hydraulic system, the working range is from 0 to 60,000 psi.
To increase accuracy and efficiency, this system is capable of using up to three different master gauges and up to eight testing gauges of the same or different ranges. Using a complete pressure gauge calibration system, gauge testing and calibration procedures can be performed fully automatically or manually with a user-friendly interface. The system's pressure control is stable and reproducible. The system is designed to test gauges, but it can also be used to test the linearity of analog-reading pressure hysteresis, repeatability, and the effect of multi-cycle. The design of the system allows it to be extended as a general precise pressure control system.
MS Windows TM based software controls the calibration procedure and provides calibration data management in this newly developed system. The software features include a flexible text and graphic report form as well as several types of error display. All the testing data can also be manipulated by Excel and other spreadsheet programs. The system controls are user-friendly and the computer screen provides a real-time display of all important information.
The calibration procedures are as following:
- Read in the data file to specify the target pressure and holding time.
- Provide a stable pressure supply at the given value and hold it for the amount of time given at the first step.
- Get the pressure reading from both the high precision gauges (master gauges) and the testing gauges (slave gauges)
- Go back to the first step, repeat step 2 and step 3 until completion.
- Collate the testing data and generate a calibration report.