Calibration of pressure balancesPressure balances are the most stable and linear devices used for the measurement of pressure. They are widely used, for example, by users for inspection and calibration of their own equipment. Calibration of pressure balances requires a laboratory capable of working to the highest accuracy.
A pressure balance derives directly from the definition of pressure as pressure = force/area. This is done by loading a piston of known area with weights to apply the force.
High repeatability and stability
The advantage of pressure balances is that they are very accurate and, when correctly used, can deliver very high repeatability of measurement. A further benefit is that of stability, which means that calibration intervals can be long, with external calibration being required less frequently.
We calibrate pressure balances over the following ranges:
- With gas as the medium, from 3,5 kPa (35 mbar) up to 40 MPa (400 bar)
- With oil as the pressure medium, from 500 kPa (5 bar) up to 500 MPa (5000 bar)
Depending on how they are used, there are two ways of calibrating pressure balances:
- Method A is the commonest, and involves measuring the pressure applied by selected weights. This is done for different pressure levels (usually five).
- Method B is the most accurate method, presenting its results in the form of the piston area and the mass of the weights. From this, and knowing the local value of g, the pressure for each given combination of weights can be calculated.