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(US), vapor
1. particles of moisture or other substance suspended in air and visible as clouds, smoke, etc.
2. a gaseous substance at a temperature below its critical temperature
3. a substance that is in a gaseous state at a temperature below its boiling point



the gaseous state of matter that arises when the gas phase of a substance is in equilibrium with the liquid or solid phase of the same material. As a rule, the term “vapor” is used when a phase equilibrium is achieved at temperatures and pressures that are characteristic of natural occurring conditions. For example, one speaks of the vapors of alcohol, benzene, iodine, and naphthalene. However, the term “vapor” is also used to refer to the gaseous state of water above the critical values of temperature and pressure, even though such values are not obtained under spontaneous, natural conditions. Conversely, CO2 is referred to as a gas below the critical temperature of 31.04°C, even though by strict usage gaseous CO2 is a vapor, since it is found in the gaseous state under spontaneous, natural conditions (seeCRITICAL STATE). The terms “gas” and “vapor” are interchangeable in the terminology of the thermodynamics of phase transformations.

The vapor of a chemically pure substance is saturated at the saturation temperature and pressure and unsaturated at temperatures above the saturation temperature when the value of pressure is fixed. Unsaturated vapor, which in industrial terminology is called superheated steam or, simply, gas, is less dense than saturated vapor. A vapor is supersaturated when the pressure is raised above the saturation pressure while the temperature is kept constant.



A gas at a temperature below the critical temperature, so that it can be liquefied by compression, without lowering the temperature.
References in periodicals archive ?
Multiple Vapor Chambers or Vapor Edge Modules, spaced 10 Km to 20 Km apart
Slessman stated, We are pleased to be working with Vapor IO.
The attorney general's lawsuit said the tanks reportedly contain more than 1,500 volatile chemicals, many or all of which "can pose a threat to human health in vapor form.
A study on Marangoni condensation (measurement and observation for steam and ethanol vapor mixture) Proc.
Although we do carry both e-cigarettes and vapor, our primary business is still [traditional] tobacco products as we are located in a rural location," she said.
Studies that show the difference between vapor and smoke
According to the company, it recently received its SuperStar Vapor Pen prototype, which went through testing and quality control.
For the record, it makes no sense to have a vapor barrier on both sides of an assembly.
Vapor intrusion refers to the potential for contaminants in the soil or groundwater beneath a building to enter the structure due to air movement that flows through cracks or crevices in the basement or lower floors.
In a temperature-driven vapor phase machine, it is very easy to program a variety of soak profiles, and programming time is minimal.
The gas stations have also installed new vapor controls that prevent harmful vapors from being released.
The overall philosophy of electronic cigarette manufacturer Vapor Corp.