Mass, volume, specific volume
Mass is the weight of gas, which is usually expressed in milligram (mg), gram (g), kilogram (kg) and ton (t. Volume refers to the volume of the container in which the gas is located. Usually cubic millimeters (mm3), Cubic centimeter (cm3), Cubic meters (m3) Indicates. Specific capacity is the volume occupied by substance per unit weight, expressed by symbol V, the unit of gas specific capacity is m3/Kg, liquid specific capacity l/kg.
Pressure, pressure, atmospheric pressure, absolute pressure, relative pressure
The force generated by the impact of gas molecules on the vessel wall when they move is called pressure. The pressure on the unit area of the container is called pressure. The unit of pressure is used to use millimeter mercury (mmHg)/square centimeter (cm2), International (statutory measurement) Pa, kPa, MPa ). After conversion, 1 mmHg = 133.3 Pa = 0.1333kPa, 1MPa = 1000kPa = 1000000Pao1ATA = 0.1 MPao.
The pressure caused by a very thick layer of atmosphere surrounding the Earth's surface to the Earth's surface or objects on the surface is called "atmospheric pressure", and the symbol is B; the pressure directly acting on the container or the object's surface, called "absolute pressure", absolute pressure value to absolute vacuum as a starting point, symbol for pabs. for pressure gauge, vacuum gauge, U-TUBE etc. instrument measured pressure called "table Pressure" (also called relative pressure), Table pressure "the atmospheric pressure as the starting point, symbol for Pg. three is the relationship between: pabs = = B + Pg.
Temperature, absolute temperature, relative temperature, critical temperature, critical pressure
Temperature is material molecular thermal motion of the statistical average values. Gas temperature is gas molecular thermal motion generated. Gas the temperature unit commonly used Celsius (℃) expressed that water frozen temperature is 0 ℃. Physics often use absolute temperature, for "K" said. Absolute temperature to-273 ℃ as zero. Celsius and absolute temperature is the relationship T = t + 273. In addition British scientists also often use "Fahrenheit temperature", symbol.
Because any gas in a temperature and pressure can liquefaction, the higher the temperature, required to liquefy pressure higher, but when the temperature exceeds a certain value, even in increase how much pressure can't liquefaction, this temperature call critical temperature, at this temperature the minimum pressure called critical pressure.
Dew point, vaporization, condensation
Is the gas water moisture in the never saturated water vapor became saturated water vapor temperature, when not saturated water vapor became saturated vapour, has the extremely thin Dew appear, appear Dew temperature called "dew point ". Dew point and stress-related, therefore also with atmospheric pressure dew point (atmospheric dew point) and pressure lower dew point points. Atmospheric pressure dew point is the finger at atmospheric pressure water condensation temperature, and pressure lower dew point refers to the pressure lower moisture condensation temperature, both with conversion relationship (available conversion table ), such as pressure 0.7Mpa when pressure dew point for 5 ℃, the corresponding atmospheric pressure (0.101Mpa) dew point is-20 ℃. In gas in the industry, if no special instructions, under dew point are atmospheric pressure dew point.
Carburetion is material by liquid state into gas process, its includes evaporation and boiling. Condensation is finger gas into a liquid process.
Purity
Purity is gas an important technical parameters. For nitrogen as an example, by National Standard nitrogen purity of divided into industrial nitrogen, pure nitrogen and high purity nitrogen three-level, their purity were 99.5% (O2 less than or equal to 0.5%), 99.99% (O2 less than or equal to 0.01%) and 99.99% (O2 less than or equal to 0.001% ).
Flow, volume flow, quality flow
Flow is the gas flow in the process, in unit time through any section of gases in the atmosphere. Flow There are two ways to said that volume flow and quality traffic. The former refers to the pass pipe line any cross section of gas volume, the latter for pass mass of gas in gas industry in general are used volume flow to m3/H (or L/H) for measurement units. Gas volume and temperature, pressure and humidity about, for comparison usually said volume flow refer to standard status (temperature for 20 ℃, pressure for 0.101Mpa, relative humidity is 65%, the traffic to Nm3/H unit, "N" indicates that standard state.
Compressed air
Air has compressibility, by air compressor do mechanical work make itself reduce volume, pressure, improve air after call compressed air. Compressed air contains many impurities: 1. water, including water mist, water vapor, condensate; 2. oil: including oil, oil steam; 3. various solid state substances such as: Rust mud, metal powder, rubber powder, tar, particle and filter material and sealing material of finely divided etc.; in addition to a variety of harmful chemical odor substances. Compressed air can pass pressurized, cooling, adsorption method to remove one of the water vapor. By heating, filtering, mechanical separation etc. method to remove liquid water.
Adsorption, membrane permeation
Adsorption is gas one or more components in porous solid surface selective concentrated, the adsorbed components called adsorption Media, porous solid called adsorbent. Adsorbent and adsorption media connection force a bond is, and adsorption media analytical by warming or lower the components in air pressure isolated pressure. Another situation is adsorption components and solid adsorbent to chemical reaction, called chemical adsorption, chemical adsorption in general cannot regenerate.
Membrane permeation finger in gas purification process in polymer separation gas is based on one or more gas components from membrane side of the selective permeability to the other side. The components dissolved in polymer film surface, and along the film transfer form a concentration difference, keep this concentration difference by Film side components of partial pressure higher than film other side the components of partial pressure.
