Vacuum system is widely used in chemical production, but there is little information about the basic concept of vacuum system, and it lacks certain systematicness. This paper will summarize the importance of its basic concepts, and what elements should be paid attention to when choosing water ring vacuum pump.
As for the basic concept of vacuum system, EVP vacuum pump manufacturers sort out the following contents.
1. Vacuum degree
Vacuum degree refers to the degree that the gas pressure in a closed space is less than the external atmospheric pressure, and its value is also between zero and atmospheric pressure, but its meaning is opposite to the absolute pressure. When the true vacuum is zero, it indicates that the closed space is in the state of atmospheric pressure; when the vacuum is equal to the atmospheric pressure, it indicates that there is no matter in the closed space in the state of full vacuum.
2. Maximum vacuum
The maximum vacuum degree, some called ultimate vacuum degree, also called ultimate vacuum, refers to the lowest absolute pressure value that can be achieved when vacuum pump is pumping, which is the basic process performance parameter of water ring vacuum pump. Each sample of its unit is different. Pay attention to unit conversion when selecting.
3. Extraction rate
It mainly includes ration, flow rate and pumping rate. The volume of space occupied by a given quantity of gas molecules at a given temperature is related to the gas pressure. Flow refers to the air flow through a certain section of the vacuum system in unit time. Pumping rate refers to the volume of gas pumped out of the closed space by the vacuum pump in unit time. The volume of gas in a closed space is related to its absolute pressure.
4. Extraction rate of closed space
The pumping rate of a closed space refers to the pumping rate needed to create a certain vacuum in a closed space, which is the rate at which the extracted gas leaves the closed space. The main influencing factors are:
(1) The amount of outside air leaking into the enclosed space. Although some closed spaces can achieve very low air leakage, almost none can achieve complete airtightness. It has been proved that air leakage must be considered.
(2) The amount of condensable vapor saturated in the leaking air. For a closed space with gas-liquid two-phase, the condensable vapor on the liquid surface will also be pumped out when vacuumizing, so the amount of condensable vapor must be considered.
(3) The amount of air and non condensable gas released in the production process.
5. water ring vacuum pump pumping rate
The pumping rate of water ring vacuum pump refers to the pumping rate of water ring vacuum pump itself, which is the rate of the pumped gas at the inlet of vacuum pump. It is another basic process performance parameter of vacuum pump.
Finally, I will summarize the elements that need to be paid attention to when selecting water ring vacuum pump. During the selection, it is necessary to preliminarily design the vacuum system to determine the specification and quantity of pipes, valves, pipe fittings and instruments, recheck the air leakage of the system, determine the fluid pressure loss and fluid conductivity in the vacuum pipeline, combine it with the calculated pressure and pumping rate of the vacuum closed space, and determine the ultimate vacuum and water ring vacuum pump of the water ring vacuum pump Pumping rate of. After comprehensive consideration, select the appropriate water ring vacuum pump.