The calculation method is as follows:
A pressure of 1 kg means that a force of 1 kg acts on a pressure of 1 cm2.
1 kg pressure = 9.8 ÷ 10 (-4) Pascal ≈ 100000 Pascal.
2Pa pressure = 2 ÷10000×1= 0.00002 (kg pressure)
Extended data:
1 kg pressure means that 1 kg force acts on 1 cm2, and 1 standard atmospheric pressure is approximately equal to 1 kg pressure.
The pressure of 1 kg is approximately equal to 1× 10 5 Pascal, and the standard atmospheric pressure 1.0 13× 10 5 Pascal.
Vacuum degree refers to the degree of gas rarefaction in vacuum state. If the pressure in the device under test is lower than the atmospheric pressure, a vacuum gauge is needed for pressure measurement. The value read from the vacuum gauge is called vacuum degree. Vacuum value indicates that the actual value of system pressure is lower than atmospheric pressure, that is, vacuum = atmospheric pressure-absolute pressure, absolute pressure = atmospheric pressure+gauge pressure (-vacuum).
The degree of gas rarefaction is usually expressed by "high vacuum" and "low vacuum". High vacuum degree means "good" vacuum degree, and low vacuum degree means "poor" vacuum degree.
The so-called vacuum degree means that the density of gas molecules in a space is less than that in a standard state (one atmospheric pressure 10 1325pa). Humidity usually refers to the number of gaseous water molecules. Besides nitrogen and oxygen, there are many other gases in the air, and moisture is one of them. So generally speaking, the greater the humidity, the smaller the vacuum, so it is not easy to vacuum when the humidity is relatively high.
There are two factors that determine the vacuum degree: one is the ultimate vacuum degree and pumping speed that the vacuum pump itself can achieve, and the other is the leakage of the whole system. Because any substance needs energy to change from solid or liquid to gas, the higher the temperature, the more active the molecular movement and the easier it is to extract.
Because it is the gas inside the vacuum-pumping element, it has a great relationship with the temperature and humidity inside the element, but it has little relationship with the temperature and humidity of the atmosphere. However, if the temperature of the atmosphere is higher and the humidity is lower, the vacuum-pumping effect will be better.
Generally speaking, water is an important factor affecting vacuum, and the most important thing to extract water is temperature. If there is not enough heat energy, the air pressure will drop due to vacuum, and some liquid water will volatilize, so that the temperature of the remaining water will drop and even become ice.
Atmospheric pressure is not fixed. In order to compare atmospheric pressure, at the 10th International Metrology Conference in 1954, scientists stipulated a "standard" for atmospheric pressure: at the sea level of latitude 45 and the temperature of 0℃, the pressure generated by a mercury column with a height of 760mm is called the standard atmospheric pressure.
Since it is a "standard", we should pay attention to the accuracy of each physical quantity according to the formula of liquid pressure. According to relevant data, the density of mercury at 0℃ is13.595×10.3 kg/m? The g value of sea level at latitude 45 is 9.80672 N/kg. Therefore, it can be concluded that the pressure generated by a 760mm high mercury column is:
P mercury = ρ mercury GH =13.595×10.3 kg/m? ×9.80672N/kg×0.76m = 1.0 1325× 10 5pa。
This is the value of 1 standard atmospheric pressure.
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