What is the blow-out method for measuring pressure and liquid level?
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What is the blow-out method for measuring pressure and liquid level? Is it to use the blown-in compressed air to isolate the corrosive medium under test from the transmitter? Am I right in saying this?
It is to isolate the medium from the transmitter; several questions related to blowout measurement can be found at the beginning of Section 4 on level measurement in the \"Instrument Technician Question Bank\"
Look at the schematic diagram of the level measurement using the blowing method, and you should understand it. If the low-pressure side of the differential pressure transmitter is connected to the atmosphere, it is possible to measure the pressure at the outlet of the purge pipe inside the tank.
It can be considered a form of pressure sealing – the higher the liquid level, the greater the pressure that can be sealed off. Assuming the medium is water and the maximum liquid level is 3 meters, the pressure setting for the air supply must be higher than 30 KPa. When the liquid level is at its maximum, 30 KPa of pressure can be sealed off within the pressure guiding tube; when the liquid level is 1.5 meters, 15 KPa of pressure can be sealed off. The excess pressure escapes in the form of bubbles, thereby allowing the actual liquid level to be determined. With this type of level gauge, care must be taken to ensure that the tubes are not blocked