Process Engineering Division – Instrumentation and Automation Section – Daily Topics – Topic No. 2020-12-16
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This post was last edited by It will be better tomorrow on 2020-12-17 08:03 in the Process Engineering Section – Instrumentation and Automation Forum – Daily Topics – Topic No. 2020-12-16. Discussion topic: 328. Using the blowing method to measure the liquid level in an open container; given that the vertical distance from the lowest to the highest liquid level is H = 2540 mm, and the density of the liquid being measured is ρ = 1.1 g/cm3, determine the pressure measurement range of the transmitter. (5 points are given only to those who provide the correct answer; additional points are awarded for a correct calculation process or detailed explanation.)
Measurement range: pgH~2pgH, that is, 1.1*9.8064*2.54~1.1*9.8064*2.54 27.38KPa~54.76KPa
1 mmH2O = 9.8064 Pa. P1 = ρgH = 1.1*9.8064*2540 = 27399 Pa = 27.399 KPa. P2 = ρgH = 1.1*9.8064*1 = 10.787 Pa
Hrg=2.541.1×103×9.8064=27400Pa; therefore, the pressure measurement range is 0～27400Pa
The liquid level in an open container is measured using the blowing method. It is known that the vertical distance from the lowest to the highest liquid level being measured is H = 2540 mm, the density of the liquid in question is ρ = 1.1 g/cm3, and the atmospheric pressure can be taken as 9.8064. Solution: When a small amount of air bubbles escape from the bottom end of the tube, the air pressure inside the tube is almost equal to the hydrostatic pressure. P=ρgH=1.1×1000×9.8064×2540/1000=27399Pa. Answer: The pressure measurement range of the transmitter is 0-27399 Pa.
The pressure from the lowest liquid level to the highest liquid level is Hρg=2540×1.1×9.8064=27550 Pa, with a measurement range of 0~27.55 kPa
P=ρgH=1.1*9.8064*2540=27399 Pa=27.399 KPa; thus, the measurement range is 0~27.399 kPa
The pressure from the lowest liquid level to the highest liquid level is Hρg=2540×1.1×9.8064=27550 Pa, with a measurement range of 0~27.55 kPa