time：2020-08-05

A: What is pneumatic technology? What is pneumatic in English?
Q: Pneumatic technology uses an air compressor as a power source and compressed air as a working medium to carry out energy transmission or signal transmission. It is one of the important means to realize various production control and automatic control. Pneumatic is the abbreviation of "pneumatic technology" or "pneumatic transmission and control", the English of pneumatic is: PNEUMATIC.

A: What is the current status of the application of pneumatic technology? Which industries and equipment are applied to pneumatics?
Q: At present, the application of pneumatic technology is very extensive, but all automated equipment can be applied to pneumatics, such as: welding production lines in the automobile manufacturing industry; assembly lines for color TVs, refrigerators and other household appliances in the electronics and semiconductor manufacturing industries. Assembly lines for various electronic products such as printed circuits; automatic air jet looms, automatic cleaning machines, metallurgical machinery, printing machinery, construction machinery, agricultural machinery, shoe-making machinery, plastic product production lines, artificial leather production lines, glass product processing lines, etc. ; Automatic measurement and packaging lines for fertilizers, chemicals, grains, food, medicines, etc.

A: What are the characteristics of pneumatic technology?
Q: The advantages of pneumatic technology: simple structure, low pressure level, safe use, convenient maintenance, simple installation; it can achieve fire, explosion, and moisture resistance.
The disadvantage of pneumatic technology is that the positioning accuracy is not high and the speed characteristics are greatly affected by the load. The output force is much lower than hydraulic pressure.

A: What is pressure? What is gauge pressure? What is vacuum? What is vacuum pressure? What is the relationship between them?
Q: Pressure is the pressure value with vacuum as the starting point. Generally, it is necessary to mark "ABS" in the lower right corner of the symbol indicating pressure, namely Pabs.
Gauge pressure refers to the pressure value higher than the local atmospheric pressure. Generally, it is not marked. If necessary, it can be marked with "e", that is, Pe.
Vacuum degree refers to the pressure value (positive value) lower than the local atmospheric pressure.
Vacuum pressure refers to the difference (negative value) between pressure and atmospheric pressure. The vacuum pressure is the same as the vacuum degree in value, but a minus sign should be added before its value.
The relationship between pressure, gauge pressure and vacuum pressure is: pressure = gauge pressure (vacuum pressure) + local atmospheric pressure

A: What are standard status and reference status?
Q: The standard state refers to the state of air at a temperature of 20°C, a relative humidity of 65%, and a pressure of 0.1MPa. In the standard state, the density of air is 1.185kg/m^3. According to ISO8778, the unit in the standard state can be marked with "(ANR)", such as 30m^3/h (ANR).
The reference state refers to the state of dry air with a temperature of 0°C and a pressure of 101.3 kPa. The air density in the reference state is 1.293kg/m^3.

A: What is perfect gas? What is the equation of state for perfect gas?
Q: Perfect gas is an imaginary gas. Its molecules are elastic particles that do not occupy volume. In addition to colliding with each other, there is no interaction between the molecules. It is completely different from the ideal gas. The equation of state for complete gas: pv=RT or written as p=ρRT=(m/V)RT

A: What is humidity? What is relative humidity?
Q: The mass of water vapor contained in each cubic meter of humid air is called humidity, which is the water vapor density of humid air. The content of water vapor in humid air has a limit. Under temperature and pressure, when the water vapor in the air reaches the possible content, the air at this time is called saturated air. The state of saturated air is called saturation. Below 2 MPa pressure, it can be approximated that the density of water vapor in saturated air has nothing to do with pressure, but only depends on temperature.
In each cubic meter of humid air, the ratio of the actual content of water vapor (ie, the water vapor density of unsaturated air) to the possible water vapor content (ie, saturated water vapor density) at the same temperature is called relative humidity.

A: What is dew point? What is the pressure dew point?
Q: For unsaturated air, the temperature at which the partial pressure of water vapor remains unchanged and the temperature is reduced to reach saturation is called the dew point. When the temperature drops below the dew point temperature, water droplets will precipitate in the humid air.
The temperature at which the wet air begins to precipitate water droplets after being compressed is called the pressure dew point. The higher the pressure, the higher the temperature at which water drops begin to precipitate.

A: What are the flow characteristics of pneumatic components? How to express the flow characteristics of pneumatic components?
Q: The flow characteristics of a pneumatic component refers to the relationship between the pressure drop at the inlet and outlet of the pneumatic component and the flow rate through the component. Cv value, Kv value, effective cross-sectional area A value under incompressible flow state, effective cross-sectional area S value, flow coefficient Cd, sonic conductance C value to street pressure ratio b value, and effective cross-sectional area A under choke flow can be used Value and the street pressure ratio b value. In addition, it can also be expressed by a flow-pressure drop characteristic curve.

A: If you know the effective cross-sectional area S, inlet pressure p1 and p2, is there a simple formula for flow calculation?
Q: q=0.248S(p2(p1-p2))^0.5(273/T1)^0.5————when 1≥(p2/p1)>0.528
q=0.124Sp1(273/T1)^0.5————when (p2/p1)≤0.528
Note: q is the volumetric flow under standard conditions, L/min; p1 and p2 are the pressures of the upstream and downstream of the pipeline, kPa; T1 is the temperature of the upstream of the pipeline, K; S is the effective cross-sectional area in the choked state, mm ^2.