How to install orifice flow meters for low-temperature and ultra-low-temperature liquids
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How should a orifice flow meter for low-temperature and ultra-low-temperature liquids be installed? Should the differential pressure transmitter be installed below or above the orifice plate? My idea is to install it below the orifice plate, so that the low-temperature liquid will flow along the pressure guide tube to the measuring end of the transmitter. However, the transmitter cannot withstand such low temperatures, and this will cause the low-temperature gas in the pressure guide tube to keep vaporizing. Therefore, the transmitter should be installed above the orifice plate, so that the low-temperature liquid does not reach the measuring end of the transmitter. Moreover, once the liquid vaporizes initially, it will fill the pressure guide tube, preventing continuous vaporization of the liquid. I’m not sure if my understanding is correct
1. If the transmitter diaphragm cannot withstand such low temperatures and there is no isolation mechanism, then there is a problem with the design. 2. Consider other instruments during the design phase, or adjust the measurement method. 3. If vaporization occurs, either upper or lower installation is inappropriate.
Bro, am I right? You’ve probably been working with instruments for no more than three years
I’ve never worked with instruments. Please provide a detailed explanation.
I realized I typed a wrong character, haha. “How does one install orifice flow meters for measuring low-temperature and ultra-low-temperature liquids?” Should the differential pressure transmitter be installed below or above the orifice plate? My idea is to install it below the orifice plate, so that the low-temperature liquid will flow along the pressure tap tube to the measuring end of the transmitter. However, the transmitter cannot withstand such low temperatures, and this would cause the low-temperature liquid in the pressure tap tube to keep vaporizing. Therefore, the transmitter should be installed above the orifice plate, so that the low-temperature liquid does not reach the measuring end of the transmitter; moreover, once the liquid vaporizes initially, it will fill the pressure tap tube, preventing continuous vaporization of the low-temperature liquid. I’m not sure if my understanding is correct?” Thank you all for your answers
There is another question I would like to ask everyone. Regarding the installation of orifice plates, I checked the \"HGT 21581-2012 Automation Installation Manual,\" which describes the installation methods for gases, liquids, and steam, but it doesn’t cover the installation method for ultra-low temperature liquids. Therefore, the installation methods mentioned there are just my guesses. Is there any specific standard that can be referred to? Or is it because ultra-cold liquids vaporize, so they are measured as gases?
How low do you mean by low temperature? So how do you measure the pressure in your pipeline? If you are afraid of vaporization, you can keep it cold. .
For example, when measuring liquid nitrogen at -196°C, the main pipeline is definitely insulated. For pressure measurement, flange drilling is used to take pressure readings, but the pressure lead pipes are not insulated. Because the measurement end of the transmitter can withstand a temperature of up to -40°C.
I checked, and the diaphragm has a lower temperature tolerance. . . . Could considering adding a protective isolation container for the transmitter be an option? . I’m offering this as a suggestion for your reference; please share the results if you get any
Who still uses orifice plates? The measurements are inaccurate, and external factors have too great an impact