Calibration using portable digital pressure indicators

摘要

What is an inch of water? The correct answer to this question has taken on increased importance with the demand for better accuracy and the introduction of digital pressure indicators. For example, lets assume that you have just received your new digital pressure indicator and you decide to verify its accuracy. The manufacturer claims 0.1percent accuracy at 100 inches of water. You set up a test using a deadweight tester and a water manometer. After placing a 100 inches of water weight on the deadweight tester, you record a reading of 99.8 inches of water on the digital pressure indicator and 100.2 inches of water on the manometer. Which is right? The answer to this question will be evident after the following discussion of manometers and deadweight testers and their relationship to digital pressure indicators. I will also include a discussion of accuracy and resolution as it applies to digital pressure indicators.