The pumping rate of the vacuum pump means, but in practical applications, the meaning of the pumping speed of our contact actually contains a variety of, below the Shenyang North really small series to bring you to understand these kinds of pumping speed!

The pumping speed of a vacuum pump is called the pumping rate, also called the volumetric flow rate. By definition, when the pump is equipped with a standard test hood and operates according to the specified conditions, the flow rate of the gas flowing through the test hood and the specified position on the test hood are measured. The ratio of equilibrium pressure obtained. More generally speaking, the pumping speed of a vacuum pump refers to the volume of gas flowing through the pump inlet per unit time. The common unit is liters per second (L/S).
However, in practical applications, the meaning of the pumping speed we contacted actually contains a variety of kinds. Let’s take a look at these kinds of pumping speeds together!

First is the nominal pumping speed
The nominal pumping speed, that is, the pumping speed of the vacuum pump, is one of the equipment parameters given by the vacuum pump manufacturer when the equipment is shipped. The pumping speed we usually touch is actually the nominal pumping speed of the vacuum pump.

The second is the geometric pumping speed, which is the theoretical pumping speed.
The geometric pumping speed is the geometric volume of the gas that can be discharged per unit time by the vacuum pump at a certain speed. It is related to the suction chamber volume of the vacuum pump, the rotor speed, and the number of suction and exhaust times of the rotor rotation. When the geometry and number of revolutions of the vacuum pump are constant, its geometric pumping speed is also determined.

However, in practice, the vacuum pump has backflow, leakage, and resistance to the intake passage during use, which may result in loss of efficiency. The geometric pumping speed of a vacuum pump product is only a theoretical pumping speed, which is actually difficult to achieve. Therefore, it is greater than the nominal pumping speed of the product.

Third, the actual pumping speed

The actual pumping speed is the effective pumping speed actually measured by the vacuum pump, or the volume of gas that the vacuum system can draw from the pumped vessel per unit time at the pressure at the outlet of the vessel. The pumping efficiency of the vacuum pump varies within different pressure ranges: when the inlet pressure of the pump exceeds a certain pressure, the actual pumping speed will start to decrease; when the working pressure of the vacuum pump is close to its ultimate pressure, the actual pumping The speed is close to zero. Therefore, the actual pumping speed is definitely less than the theoretical pumping speed, but it should be noted that in general, we will choose to work within the optimal pumping speed range of the vacuum pump. In the stable pumping speed section, the actual pumping speed is greater than the nominal pumping speed. of.
At the same time, the flow conductance of the vacuum system piping also limits the pumping speed of the vacuum pump.

The nominal pumping speed, geometric pumping speed and actual pumping speed can be simply understood as: geometric pumping speed > actual pumping speed > nominal pumping speed.

In addition, the pumping speed of the vacuum pump is also related to the type of gas. The given pumping rate only represents the pumping rate for a certain gas. If there is no special indication, it means more than air.

Shenyang North vacuum is a professional vacuum furnace manufacturer in China.