Frequently Asked Questions
What to learn more about fans? What is a motor? What is system impedance?
The answers to these and more can be found below.
What is the life expectancy of a fan?
What is airflow?
What is static pressure?
What are air performance curves?
Air performance curves are graphs showing air flow characteristics: airflow (cfm) versus static pressure (in. wc) and airflow (cfm) versus blower speed (rpm).
Are your fans dynamically balanced?
What is the system operating point?
What is system impedance?
What are fan laws?
What is motor insulation?
Do plug and cord sets work in 115 and 230 volts?
Can the motor position on the crossflow blower be rotated?
Do the blower motors have agency approval for the US and Canada?
What is the minimum recommended starting voltage for AC blower motors?
Example: Minimum starting voltage: 111 x .75 = 86V
Are the blowers date coded?
029 = week 2, 1999
4999 = week 49, 1999
0500 = week 5, 2000
Can all 60 Hz blower motors operate on a frequency of 50 Hz?
Are the blowers available with European voltages and approvals?
What is a motor?
What is an AC induction motor?
There are two types of single phase AC induction motors commonly used for direct fan applications: shaded-pole and permanent split capacitor.
What is a shaded-pole motor?
What is a permanent split capacitor motor?
What are the differences in motor speeds?
How do you change speed motor control?
How can you change the voltage?
How do you change the frequency?
What is a brushless DC motor?
What is a backward curved impeller?
Does Sofasco build fans, blowers, or motors with moisture or corrosion protection?
How is fan life defined?
Do you have a thermostatically controlled fan?
How do you read an air performance curve?
What are some general guidelines on mounting fans and blowers?
What is an IP rating?
Can I repair the blower/fan myself?
Does Sofasco sell replacement parts?
How do I tell the air flow direction?
What is the difference between air intake over discharge over struts?
What is an external motor?
What’s the maximum voltage you can apply to a blower?
What is the definition of voltage range?
How does fan and blower performance change at 1,000 and 2,000 meters altitude?
What about shipping and delivery?
How to choose a suitable fan for our equipment?
How to measure noise level ?
What's the difference between noise level and abnormal noise?
How to test abnormal noise?
How to reduce noise?
- System Impedance - Higher airflow will create higher noise level. Likewise, the higher system impedance created by the system, the higher airflow is required in order to achieve the cooling effect. That is, users need to reduce the system impedance as low as possible in order to achieve the least noise of airflow.
- Flow Disturbance - The turbulent air generated by the obstructions along the path of airflow will raise the system noise. Therefore, users have to avoid any obstructions in the critical inlet and outlet area as much as possible.
- Fan Speed - As you know, a higher speed fan will generate greater noise compared to a low speed fan. Users have to try their best to choose a lower speed fan as much as possible.
- Fan Size - A larger size fan will generate a much lower noise level then a smaller size fan does while creating the same airflow. Users shall try to use larger fan with lower speed if space is allowed.
- Temperature Rise - Airflow is inversely proportional related to the allowable temperature increase in a system. A little change in the allowable temperature rise will lead to a significant change in the airflow requirement. If there is a little compromise to the limit imposed on allowable temperature rise, there will be a considerably less amount of airflow required. It will lead to remarkably reduction in the noise level.
- Vibration and Resonance - We recommend using some soft and flexible isolator to avoid vibration transmission.
- Voltage - The higher voltage applied to the fan; the higher vibration it will generate as will as rpm, Correspondingly, it will create a higher noise level.
- Fan Design - Users have to choose reliable fans to avoid higher acoustic noise caused by improper mechanical and electrical design of the fan.
Do fan blade shape and number of blades matter?
What is a sleeve bearing fan?
What is a ball bearing fan?
What is a 3-wire fan?
What is a hydro bearing?