Regarding the insertion depth of the gauge

How is the insertion depth of tanks and storage tanks calculated? Newcomer

What instruments are you talking about? Thermal resistor?

If the diameter of the thermal resistance tube is less than DN80, an expansion tube is used; the tank and reservoir need only be inserted 150 mm into the inner wall of the equipment.

If the diameter of the thermal resistance tube is less than DN80, an expansion tube is used; the tank and storage vessel are inserted 150 mm into the inner wall of the equipment, at a distance of approximately 500 mm from the bottom of the tank

Newcomers want to know if there are any unified standards for thermal resistors and thermocouples?

The previous version of the selection specifications required that the thermometer be inserted to a depth of 1/3 to 2/3 of the pipe length; generally, 1/2 of that length was used as the insertion depth. However, according to the \"Specifications for the Selection and Design of Automated Instruments\" (HG/T20507-2014): For pipe thermometers (applicable only to process pipes; when devices such as heating furnaces have no impact on the strength of the sleeves, the insertion depth is determined based on actual requirements): there are common problems in calculating the vibration frequency when the pipe diameter is too large. Specification: The end of the temperature sensing element should be immersed in the inner wall of the pipe for a length of not less than 50 mm, and not more than 125 mm (it is no longer required to be inserted to the center of the pipe). This requirement is mainly aimed at the calculation of the strength of thermometer casings. In many applications involving high pressure, high temperature, and high flow rates, if the insertion depth is too great, the calculated strength of the casing often fails to meet the required standards; hence this length limit was established. The regulations state that it is \"not advisable\" to use such long depths, but it is not mandatory. When the strength calculations meet the requirements, I believe it is still better to insert the casing to the center of the pipe. However, for pipes larger than DN400, such a requirement does not apply; otherwise the thermometer would have to be very long, which is unnecessary. For the temperature sensing element, the length of its tip immersed in the inner wall of the pipe should be no less than 50 mm and no more than 125 mm (it is no longer required to be inserted to the center of the pipe). ”Understanding of this sentence: According to fluid mechanics, and based on the flow pattern of the fluid within the pipe, it is believed that at a distance of 50 mm from the inner wall of the pipe, the flow velocity of the medium is roughly the same as that at the center of the pipe; therefore, it is considered that the temperature at this point can accurately reflect the actual temperature of the medium.

All these calculations are carried out by the process engineering team. In the case of thermocouples, the calculations are done by the manufacturer, who requires you to provide them with the flow rate. Manufacturers usually have a specified value; if the flow rate exceeds this value, it becomes necessary to reinforce the pipe using additional elements. I’m not entirely sure about the details. When reinforcing the pipe, it’s important to note that if the wall thickness is very high, it might be impossible to fit the reinforced components after the reinforcement is done, especially in pipes with a wall thickness of SCH160 or higher. Generally, the flanges for thermocouples are DN40 in size, and there’s no problem with that