离心通风机的选型对于该风机来说是重要的一环，因为选型的正确与否关系到离心通风机能否发挥出最大效能，产生最大工作效率。那如何对其合理进行选型呢？下面小编就来解答这个问题，给读者一些参考性的指导与建议，分析如下。
The selection of centrifugal fans is an important part of the fan, as the correctness of the selection is related to whether the centrifugal fan can achieve maximum efficiency and produce maximum working efficiency. How to make a reasonable selection for it? Below, the editor will answer this question and provide readers with some reference guidance and suggestions. The analysis is as follows.
选型第一阶段：
The first stage of selection:
离心通风机要选型，首先要确定气体的流量、压力、密度，这是离心通风机选型过程的三要素，具体为：
To select a centrifugal fan, the first step is to determine the gas flow rate, pressure, and density. These are the three elements of the centrifugal fan selection process, specifically:
密度是选型过程中最为关键的第一要素，若未给定密度则需根据风机的工况环境，如海拔、当地大气压、工作温度、气体的标密来计算或换算出工况气体的密度。
Density is the most crucial first element in the selection process. If density is not given, the density of the working gas needs to be calculated or converted based on the operating environment of the fan, such as altitude, local atmospheric pressure, working temperature, and gas density.
压力是风机选型的第二要素，根据给定或计算出的工况密度，将工况压力换算为风机标准状态下压力。如风机带进气箱或消声器，需考虑其压力损失，可经过计算或估算，估算损失一般在100—300Pa之间。
Pressure is the second element in fan selection. Based on the given or calculated operating density, the operating pressure is converted into the pressure under the standard state of the fan. If a fan is equipped with an intake box or muffler, its pressure loss needs to be considered. After calculation or estimation, the estimated loss is generally between 100-300Pa.
流量是选型过程的第三要素，如系统要求气体的质量流量，则需要将气体质量流量换算为风机标准状态下的容积流量。如系统要求气体的容积流量，则风机标准状态下的容积流量与工况下的容积流量相同。
Flow rate is the third element in the selection process. If the system requires a mass flow rate of gas, it is necessary to convert the gas mass flow rate to the volumetric flow rate under the standard state of the fan. If the system requires a volumetric flow rate of gas, the volumetric flow rate of the fan under standard conditions is the same as that under operating conditions.
接下来就是求风机的比转数，因为比转数计算是风机选型过程中的重要步骤，是判断风机选用具体模型的主要依据。将换算到风机标准状态下的性能参数和转速代入比转数的计算公式，根据不同的转速可求出不同的比转数，一阶比转数是单吸风机的依据；二阶比转数是双吸风机的依据。
The next step is to calculate the specific speed of the fan, as the calculation of the specific speed is an important step in the fan selection process and the main basis for determining the specific model of the fan. Substitute the performance parameters and speed converted to the standard state of the fan into the calculation formula for specific speed, and calculate different specific speeds based on different speeds. The first order specific speed is the basis for a single suction fan; The second order specific speed is the basis for the double suction fan.