Relative/absolute pressure testing allows for a compact setup, the benefits of which are high reliability and a broad range of measurements. By using this method, the specimen is subjected to pressure and the differential is measured over a set period of time.
Relative pressure testing measures the ambient pressure differential, which is why it is known as overpressure testing when the testing pressure is greater and vacuum testing when it is lower.
Absolute pressure testing uses the point of absolute zero (perfect vacuum) as the reference point to determine the testing pressure. The resolution is contingent upon the testing volume and pressure. This testing method enables a 1 Pa resolution.