Classification of medium states
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As the title suggests: Classification of medium states: gas, solid, liquid. Today, I heard from an experienced instrument technician that there is actually another state: steam. I wonder if anyone has heard of this claim. I searched extensively online, but there’s no clear answer. I hereby seek advice from all the experts. Feel free to share your thoughts! Daxie.
Physically, there are three states of matter. In practical applications of instruments, gas-liquid mixtures come into play, as do mixtures with different proportions of liquids; there are also situations involving solids and liquids at their critical points, such as ice-water mixtures. However, these should not override the physical definitions. If steam is considered a separate type of substance, then shouldn’t saturated steam and superheated steam be classified separately as well?
This post was last edited by zxb1990 on 2015-6-4 17:21. So do you think steam (whether high-pressure, low-pressure, saturated, or superheated) should be classified as a gas or a liquid?
By steam, you mean water vapor, right? There are two states of water vapor: superheated steam and saturated steam. Superheated steam is in a gaseous state, while saturated steam is in a mixed gas-liquid state.
‘Just like with LNG, for example inside a spherical tank, the interface of LNG is actually in a boiling state, with a \"gray zone\" between the gas and the liquid. It is highly dependent on the environment in which the medium is located (temperature, pressure).
Speaking of water, there is ice, water, saturated steam, superheated steam, and supercritical water； Water in a supercritical state is neither a liquid nor a gas; it is a supercritical fluid.
For instrument selection, the medium state should be one of 4 types: gas, liquid, solid, and water vapor.
I think it’s still a gas; in a saturated state, without cooling, that is, in the absence of liquid droplets, it remains in gaseous form
This post was last edited by waaabc on 2015-6-5 at 11:57. There is indeed such a statement; the definition of pressure pipelines includes steam as a separate category, and many standards treat steam as a special type of medium. There’s no need for the original poster to worry about this; it’s simply because steam is a high-temperature gas, and a two-phase state of gas and liquid can also occur. Such substances are essential in most enterprises, so listing them separately shows an emphasis on steam as a medium.
Medium: When one substance exists within another, the latter serves as the medium for the former. Therefore, in a chemical plant, anything that exists within towers, reactors, tanks, vats, pipelines, pumps, and other equipment is considered a medium. Think about how many types of process media we usually talk about…………
There are two words, ‘steam’ and ‘vapor’; the former refers specifically to water vapor, while the latter denotes the gaseous state of certain substances at high temperatures.