Why does the pressure tube need to have a certain slope? !

Are you talking about the pressure-taking point of the orifice flowmeter? Otherwise, I really didn’t pay attention to whether it is slanted. I think it is because the slant reduces the resistance and saves space.

The pressure-taking direction of the pressure guiding tube is determined based on the characteristics of the measuring medium. For example, when measuring liquid, the pressure is measured within a range of 45° horizontally downward to ensure that the liquid can fill the pressure-guiding tube and eliminate the gas in the pressure-guiding tube.

It's not a flow meter, it's a differential pressure gauge. When I was working on a project for a foreign company, the Germans required a certain slope. Later I checked and found that a certain slope was indeed required, but I don’t know why.

We are measuring gas. But even for measuring liquids, the level can ensure that the liquid fills the pipe.

Won't. Is it necessary to install it diagonally to reach the theoretical centerline of the pipeline?

GB 50093-2013 Specifications for Construction and Quality Acceptance of Automated Instrument Engineering has relevant statements on this issue. Please refer to the provisions of the following standard markings.: When measuring liquid, it is required to draw it out horizontally to 45 degrees downward. The purpose is to ensure that the inside of the pressure tube is filled with liquid. When gas is generated for any reason, the gas will move upward along the pressure tube until it reaches the main pipe, thus ensuring that the pressure tube is filled with liquid and ensuring measurement accuracy. When measuring gas, it is required to lead it out from the upper part of the pipeline to ensure that the inside of the pressure tube is filled with gas. No matter what the reason is, when liquid is generated, the liquid will move downward along the pressure tube until it reaches the main pipeline to prevent a liquid column from being generated in the pressure tube and affecting the measurement accuracy.

When measuring gas, the differential pressure gauge should be higher than the pressure-taking point, and the pressure-taking point should be above the horizontal center line of the cross-section of the pipeline to prevent liquid accumulation in the pressure pipe.

There is no problem with horizontal installation, and it also complies with the installation requirements in the installation manual.

Please see the attached picture. The tilt is to avoid gas-liquid entrainment and sample gas as much as possible.