Pressure tapping method for throttling devices

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　　There are 5 methods for taking pressure readings from throttling devices; for orifice plates, these include corner connection pressure taking, flange connection pressure taking, radial distance pressure taking, theoretical pressure taking, and pipe connection pressure taking. For nozzles, there are only two types of pressure tapping: corner tapping and radial distance tapping. 　　(l) For corner-type pressure tapping, the distances between the axis of each pressure tap hole on the upstream and downstream sides and the front and rear end faces of the orifice plate (nozzle) are each equal to half the diameter of the pressure tap hole, or equal to half the width of the pressure tap gap; as a result, the point where the pressure tap hole penetrates is exactly at the same level as the end face of the orifice plate. Corner-type pressure tapping includes pressure tapping via annular chambers and pressure tapping through individual drilled holes. 　　(2) For flange pressure tapping, the distance from the center of the pressure tapping holes on the upstream and downstream sides to the front and rear end faces of the orifice plate is (25.4 ± 0.8) mm. 　　(3) The radius is defined as 1D being the distance from the center of the pressure tap on the upstream side to the front surface of the orifice plate (nozzle), and 1/2D being the distance from the center of the pressure tap on the downstream side to the back surface of the orifice plate (nozzle). 　　(4) In the theoretical pressure tapping method, the distance from the center of the pressure tap on the upstream side to the front surface of the orifice plate is 1D ± 0.1D, while the distance from the center line of the pressure tap on the downstream side to the rear surface of the orifice plate varies depending on the value of β = d/D. 　　(5) The centerline of the pressure tapping hole on the upstream side of the pipe is 2.5D from the front surface of the orifice plate, while the centerline of the pressure tapping hole on the downstream side is 8D from the rear surface of the orifice plate. 　　Among the above 5 pressure tapping methods, the corner connection method is the most commonly used, followed by the flange pressure tapping method. The pressure measurement locations for the main media of gases, liquids, and vapors differ fundamentally. If you have any additional comments, feel free to leave them for discussion.