Process Engineering Division – Instrumentation and Automation Section – Daily Topics – Topic No. 2020-12-13
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Process Engineering Division – Instrumentation and Automation Section – Daily Topics – Topic No. 2020-12-13: Discussion topic: 325. There is a pressure with a range of 320–360 KPa. If measurements are taken using the two pressure transmitters A and B listed below, which one will provide more accurate readings under normal conditions? Pressure transmitter A: Class 1, 0-600KPa ； Pressure transmitter B: Class 1, 250-500 KPa (5 points for the correct answer only; additional points for a correct calculation process or detailed explanation)
When using transmitter A, the maximum error in the measurement value is: δmax = ±1% × (500 – 0) = ±5 Kp. When using transmitter B, the maximum error in the measurement value is: δmax = ±1% × (500 – 250) = ±3 Kpa. Therefore, transmitter B provides higher measurement accuracy.
Pressure transmitter B has a range of only 250 Kpa – how can it be used to measure pressures above 320 Kpa? ? So, only pressure transmitter A can be selected here for measurement.
Pressure transmitter B: Class 1, 250-500KPa
Pressure transmitter A: Class 1, 0–600 KPa, with an allowable error of ±6 kPa; Pressure transmitter B: Class 1, 250–500 KPa, with an allowable error of ±2.5 kPa； Therefore, pressure transmitter B provides more accurate measurements.
Pressure transmitter A: Class 1, 0–600 KPa, with a measurement error range of ±6 kPa; Pressure transmitter B: Class 1, 250–500 KPa, with a measurement error range of ±2.5 kPa； Therefore, pressure transmitter B provides more accurate measurements.
Pressure transmitter B: Class 1, 250-500KPa
B also has a precision error of 1%; the error of the B transmitter is 2.5 kPa, which is a small error
When using transmitter A, the maximum error in the measurement value is: δmax = ±1% × (500 – 0) = ±5 Kp. When using transmitter B, the maximum error in the measurement value is: δmax = ±1% × (500 – 250) = ±3 Kpa. Therefore, transmitter B provides higher measurement accuracy.