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1. What is the correct location for installing pressure sensors on liquid, gas, and steam pressure measuring instruments? a. When measuring gas: To allow any small amount of condensate present in the gas to flow back smoothly into the process pipeline, without entering the measurement pipeline or the instruments, the pressure tapping point should be located in the upper half of the pipeline ； b. When measuring liquids: To allow the small amount of gas that forms within the liquid to return smoothly to the process pipeline, without entering the measurement pipeline or the instruments, it is best for the pressure tapping point to be at an angle of 0–45° below the horizontal centerline of the pipeline. c. When measuring steam: It is necessary to maintain a steady level of condensate within the measurement pipeline, while also preventing solid particles from the bottom of the process pipeline from entering the measurement pipeline or the instruments; in this case, it is best for the pressure tapping point to be at an angle of 0–45° above the horizontal centerline of the pipeline. 2. The meanings and interrelationships of absolute pressure, atmospheric pressure, gauge pressure, and vacuum: The pressure in a state of absolute vacuum is called absolute zero pressure, and the pressure expressed relative to this absolute zero pressure is known as absolute pressure. Gauge pressure is a pressure expressed relative to atmospheric pressure; therefore, it differs from absolute pressure by exactly one atmosphere, which is 0.1 MPa. If the absolute pressure of the fluid being measured is lower than atmospheric pressure, the pressure indicated by the gauge is negative, and this value is referred to as vacuum level. Absolute pressure = atmospheric pressure + gauge pressure. 3. What are the characteristics of intelligent transmitters? 1) Temperature characteristics and static pressure characteristics have been significantly improved ； 2) High precision ； 3) Large adjustable range ratio ； 4) Has remote control setting function ； 5) It has a self-diagnosis function. 4. What is the HART communication protocol? What is the DE communication protocol? HART protocol: A protocol in which digital signals are superimposed on analog signals, allowing both to be transmitted simultaneously. DE protocol: A protocol in which digital signals and analog signals are transmitted separately, with the analog signal needing to be interrupted when digital signals are being transmitted. 5. What is the damping of a transmitter? That is, the speed at which the transmitter’s output changes in response to variations in the parameter being measured. 6. Why is the accuracy of flange transmitters lower than that of ordinary transmitters? This is because flange transmitters have an additional remote flange diaphragm box, which introduces an extra conversion step; as a result, the error is increased by the conversion error associated with the flange diaphragm box, on top of the original error.