Why is the entry \"Design vacuum level: Full vacuum\" included in the tower’s data table (as shown below)? Thank you!
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Why is the entry \"Design vacuum level: Full vacuum\" included in the tower’s data table (as shown below)? Wouldn’t the design pressure be sufficient? Thank you! Tower’s data table: Operating pressure (absolute pressure): 90–145 mmHg; Operating temperature: 150°C; Design pressure (gauge pressure): 0.18 MPa; Design vacuum level: Full vacuum; Design temperature: 180°C
As can be seen from the data table extracted by the poster, this is a vacuum tower. The design pressure ranging from full vacuum to 0.18 MPa (g) is correct. The original poster also needs to tell us what kind of materials this tower is used to process This pressure range is very important for equipment design, but the extent to which it has an impact requires the assistance of experts in equipment design to explain.
As can be seen from the data table extracted by the poster, this is a vacuum tower. The design pressure ranging from full vacuum to 0.18 MPa (g) is correct. The original poster also needs to tell us what kind of materials this tower is used to process This pressure range is very important for equipment design, but the extent to which it has an impact requires the assistance of experts in equipment design to explain.
Design pressure (gauge pressure): 0.18 MPa. Design vacuum level: full vacuum. Design temperature: 180°C. These are the design parameters; generally, the design space for equipment is larger than the working space, with some designs having a space that is 1.5 times larger. Full vacuum means that it truly operates under absolute vacuum conditions, and the tower works fine! ! ! ! The designed operating pressure is 0.18 MPa; the actual operating pressure must not exceed this value, as doing so poses a risk. The design temperature is 180 degrees; similarly, the temperature allowed during operation must not exceed 180 degrees, as exceeding this limit may cause problems with the equipment. The manufacturer is not liable for any accidents or losses resulting from operating the equipment beyond the specified design conditions.
The design parameter requirements stem from the manufacturing process; a full vacuum may be required for the operation of the process, or it may be necessary in maintenance/accident situations. At 180 degrees, the requirement for full vacuum can be met, which is considered from the perspective of external pressure equipment. And 0. 18MPA is based on internal pressure, and the strength design formulas for the two are different; therefore, calculations must be done separately for each. Especially when the internal pressure is not very high, it is necessary to calculate the tower based on the external pressure according to the degree of vacuum. There must be a range for pressure design. It is incomplete if there is only an upper pressure limit and no lower one. If the temperature difference is too large, full vacuum operation may be risky.
Although the design pressure of this tower is 0.18 MPa gauge, based on the specified process parameters, the tower operates under negative pressure. For equipment that operates under negative pressure, it is generally required in the design phase that the equipment be capable of operating under full vacuum conditions, so that in the event of a failure in the vacuum system during actual production, the tower will not be damaged.
It can be said that any tower operated under negative pressure must be designed to function at full vacuum, and its pressure tests must comply with negative-pressure testing, that is, full-vacuum testing. At least all the negative-pressure towers I have come across are designed this way. I’m not sure if there are any relevant regulations regarding this; I hope professionals can also provide the relevant standards in this area.
The design temperature and design pressure of a device serve as the basis for its strength calculation. For devices that operate under negative pressure, in addition to considering the device’s strength, it is also necessary to take into account the risk of instability, especially in devices with large diameters.