How to select the suitable centrifugal fan? by Xianrun Blower

Centrifugal fan selection is an important part, because it is related to  whether the centrifugal blower can play the highest efficiency.

xianrun blower direct drive centrifugal blower

The 1st Stage of Selection:

The first thing is to confirm the air flow, air pressure, density of gas, which are the three basic elements in centrifugal fan selection process. 

1. Density is the primary elements in the selection process, if the density is unknown, it needs to calculate or convert the density according to the working environment, such as altitude, the local atmospheric pressure, operating temperature, and so on.

2. Air pressure is the second element in the centrifugal fan selection, according to a given or calculated the density of working condition, then convert the working pressure to the fan pressure of standard condition. If the fan is equipped with inlet box or silencer, 
it needs to consider the pressure loss, estimated losses are generally between 100-300 pa after the estimation.

3. Air flow is the third element in selection process. If the system require the gas mass flow rate, you need to convert the gas mass flow to volume flow rate in standard condition.

xianrun blower coupling drive centrifugal blower

The next step is to circulate centrifugal fan specific speed, which is an important step in the centrifugal fan selection process, as well as the main basis to choose centrifugal blower specific model.

Air volume/air flow		m3/h
Total pressure or static pressure		Pa
Medium temperature		°c
Voltage		V
Frequency		Hz
Altitude of operation place		m

How to adjust centrifugal fan to the best efficiency?

Under different condition, the centrifugal fan efficiency is different. 

1. Full-voltage starting or reduction voltage starting are both OK for centrifugal fan,but the electric current of full-voltage starting is about 5 to 7 times to the rated current. 
When electrical capacity is insufficient, reduction voltage starting is better.

2. Before centrifugal fan commissioning, check whether the wiring methods are consistent with the wiring diagram; whether the working voltage of power supply is conform to the requirements; whether the power supply is lack of phase; whether the capacity of electrical components meet the requirements.

xianrun blower centrifugal fan

3. At least two professional persons check centrifugal fan commissioning, one controls power supply,the other observes the blower working. Stop the centrifugal fan immediately and check for any abnormal phenomena; during the blower running, check the rotation direction firstly; check whether every phase running current is more than rated current.  
Stop running after five minutes, and confirm no abnormal phenomenon, then start operation.

4. Check whether the input current is normal when the fan speed reach normal speed, and centrifugal fan running current should not exceed rated current.If the current exceeds its rated current operation, check whether the supply voltage is normal.

adjust centrifugal fan

5. Centrifugal fan motor power is the biggest power when wind chassis and air inlet open fully. It is better to close the valves of the inlet duct and outlet duct in advance, during the centrifugal blower commission, then open the valves gradually to achieve the required conditions, and and pay attention to whether the working current is more than rated current.