What Is a Pressure Calibrator?
A pressure calibrator is an instrument used in the maintenance of pressure gauges.
Also called a pressure standard, it is used to calibrate pressure gauges. The reason why pressure gauges need to be calibrated is to ensure conformity to standards and laws, and to ensure traceability. If calibration is not performed at a certain cycle, reliability is lost and the measurement data cannot be trusted.
Also, if the calibration range is significantly out of range, large measurement errors will occur. In addition, there is a possibility of accidents such as damage to the pressure vessel. Therefore, it is necessary to consider whether calibration should be performed within the general calibration range and to determine the calibration cycle of the pressure gauge.
Calibration documents for calibrating a pressure calibrator include an inspection certificate, inspection report, traceability system chart, and a copy of the calibration certificate of the standard instrument, etc.
Uses of Pressure Calibrators
Pressure calibrators are mainly used in industrial applications. The following are examples of applications of pressure calibrators.
- Maintenance of pressure gauges and pressure sensors
- Maintenance of pollution control equipment
- Quality assurance for product development and product manufacturing lines
As shown above, they are mainly used for maintenance of pressure gauges and other instruments. In addition, when pressure gauges are manufactured, their functions are checked using pressure calibrators.
Principle of Pressure Calibrators
Deadweight pressure gauges, often used as pressure calibrators, are based on the most basic pressure principles and have long been highly reliable pressure calibrators. Pressure is defined as the vertical downward force multiplied by the cross-sectional area.
Deadweight pressure gauges are measured by a cylinder, a piston, and a weight of known weight on the piston. The cylinder is fitted with a piston that moves without friction. There is pressurized fluid in the cylinder, which is held back by the gravity of the deadweight through the piston.
Since a balance of forces is generated there, the pressure is calculated and measured using the gravity of the deadweight and the cross-sectional area. In order to improve the accuracy of deadweight pressure gauges for gases, the fit of the piston and cylinder and the surrounding environment may also be taken into consideration.
For this reason, the piston and cylinder are carefully cleaned, but the effect may be small if the inside diameter is large. However, more stable performance can be expected from deadweight pressure gauges for liquids than from deadweight pressure gauges for gases.
Types of Pressure Calibrators
The most commonly used pressure calibrators are deadweight testers. Deadweight testers are available for hydraulic and pneumatic pressure, and the model is selected according to the pressure gauge to be calibrated and the application. Another selection criterion is whether the pressure gauge is portable or stationary.
Deadweight testers can measure mechanical and electrical pressure, but cannot calibrate equipment that measures high vacuum conditions, such as ionization vacuum gauges. Other electronic pressure calibrators are also available.
Electronic pressure calibrators have the ability to record various types of data in memory, and are sometimes used to calibrate pressure transmitters, pressure switches, and electro-pneumatic/air-electric transducers. There are two types of pressure gauges mainly used in pressure calibrators: digital pressure gauges and mechanical pressure gauges.
Other Information on Pressure Calibrators
Calibration Method of Pressure Gauges
The calibration method uses a gas or liquid as the pressure medium, repeatedly raises and lowers the pressure, and calculates the calibration value from the average value. Calibrators generally used for calibration are dead-weight pressure balances and digital pressure gauges.