How to determine the pressure calibration equipment you need

There are thousands of different pressure measuring devices. How can you decide which instruments to invest in to calibrate them? When you are considering the purchase of pressure calibration equipment, start by taking these two steps:

• Compare specifications of the device under test (DUT) and the pressure calibrator. Gauges, transmitters, transducers, and similar pressure measurement devices have specifications that describe how well they measure pressure. Pressure calibrators also have specifications. To make sure that your calibrator is accurate enough to calibrate a pressure measuring device, you’ll want to compare the specifications of the measurement device and the calibrator using a test accuracy ratio (TAR). A TAR is the ratio between the stated accuracy of the DUT and the accuracy of the calibrator. A good TAR is typically 4:1. By keeping a 4:1 ratio you are less likely to falsely accept or reject a pressure gauge based on the outcome of your calibration, especially when the error is near the established tolerance. 
• Determine rangeability. Rangeability is the ratio of the maximum to the minimum specified measured value at which an instrument has an acceptable performance. It depends on the DUT’s specification, the calibrator’s specification, and the full scale of both devices. The bottom line is that you can calibrate twice as many DUTs with one calibrator if it has twice the rangeability.