A known volume gas is compressed to a smaller volume whose final value provides an indication of the applied pressure. The gas used must obey Boyleâs law given by;
Where, P1 = Pressure of gas at initial condition (applied pressure). P2 = Pressure of gas at final condition. V1 = Volume of gas at initial Condition. V2 = Volume of gas at final Condition.
Initial Condition == Before Compression. Final Condition == After Compression.
A known volume gas (with low pressure) is compressed to a smaller volume (with high pressure), and using the resulting volume and pressure, the initial pressure can be calculated. This is the principle behind the McLeod gauge operation.