Temperature and pressure of low-pressure, medium-pressure, and high-pressure steam
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Why is it that in all the foreign materials I’ve seen so far, the pressure of low-pressure steam is always 120°C (0.1 MPAG), the temperature of medium-pressure steam is 180°C, and the temperature of high-pressure steam is 250°C?； And when I designed it based on these data, the judges said I used steam incorrectly? Are the steam temperatures domestically 180°C (low pressure), 250°C (medium pressure), and 300°C (high pressure)?
The classification of steam (low pressure, medium pressure, high pressure) varies according to different standards and industry regulations; therefore, the situation you are facing may be due to differences between these various standards. Generally, steam is classified by pressure and temperature as follows: – **Low-pressure steam**: This refers to steam with a pressure of 1.0 MPaG or less (approximately 10 bar, which is above atmospheric pressure). The temperature can be above 100°C, but not too high. However, the actual pressure corresponding to 120°C is slightly higher than atmospheric pressure, falling within the category of low-pressure steam that is only slightly above atmospheric pressure. - **Medium-pressure steam**: The pressure is usually between 1.0 MPaG and 3.5 MPaG, while the temperature ranges from approximately 180°C to 240°C; these values can vary depending on the specific application and industry standards. - **High-pressure steam**: The pressure is above 3.5 MPaG, and the temperature is usually above 240°C, sometimes even reaching 300°C or higher. The classifications of 120°C (0.1 MPaG), 180°C, and 250°C mentioned in foreign sources may be based on standards specific to certain industries or regions. Domestic standards may vary; for example, the 180°C (low pressure), 250°C (medium pressure) and 300°C (high pressure) values you mentioned are likely based on Chinese standards or those specific to certain industries. When designing a steam system, it is important to refer to the industry standards and regulatory requirements of the location where the project is situated. If the judges point out an error in usage, it may be because the specific standards or regulations that the project must comply with differ from those in the foreign materials you referred to. At the initial stage of design, it is best to identify and comply with local standards and regulatory requirements; if necessary, one can seek advice directly from the standards-setting bodies or industry experts. .