Why are the pressure guiding lines at a 45-degree angle below the pipe when measuring steam with a constant velocity tube?
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As shown in the figure, why is pressure taken in this way when using a pitot tube to measure steam?
Allow the gas in the liquid pressure tapping tube to overflow automatically
The liquid is like this; what about steam? The steam pressure measurement using a orifice plate is taken at an angle of 45 degrees above
I’m a layperson, so let me share my understanding. No matter where the pressure sampling point is located, it’s essential to obtain representative data. When measuring gases, any presence of liquid will inevitably affect the measurement results. Similarly, when measuring liquids, we certainly don’t want any gas to be present. Therefore, the upper and lower points are selected to reduce the impact of interference factors. However, steam is in a gas-liquid mixed state; therefore, it is more appropriate for the sampling point to be within 45 degrees below the horizontal plane. As shown in the red area in the figure below:
The uniform velocity tube flow meter belongs to the differential pressure type of flow meters. When measuring gases flowing upward, it prevents liquid from being present in the pressure guiding tubes; when measuring steam or liquids flowing downward, it ensures that the pressure guiding tubes are filled with liquid rather than gas, thereby enabling more accurate measurements.
Personally, I believe the advantage of this installation method is that condensate can fill the pressure tapping pipe; firstly, this prevents high-temperature steam from directly contacting the measuring element and causing damage； Second, prevent a mixture of steam and water from forming inside the pressure tap, as this can cause measurement errors
The orifice plates are installed upward, but balance tanks are added in all cases. I guess he didn’t install a surge tank for this downward installation
Steam measurement. The transmitter is required to measure steam condensate. Following this requirement is fine.