Motor is the heart of fan. Its design relates to the fan’s performance. If the motor got smaller, the impeller area could be larger in same frame size. Consequently, the airflow increases. Under the same dissipation performance, Zaward’s fans need less RPM than the other manufacturers’ fans.
Thus, they work more quietly.
Bearing and Life
Life expectancy is one of the most important factors of fan’s performance. Bearing system and the working environment decide the main concern of fan’s life expectancy. Zaward has four bearing systems. The following table [Table 1] lists the bearing types and their life expectancy under normal working environment.
1. Acoustic measurement
The sound pressure level is measured in an anechoic chamber with very quiet background. All sound pressure test conditions should follow ISO7779 standard. For normal situation, the microphone is positioned one meter from the air intake of the testing fan. It shall be hanged in clean air. Refer to [Diagram 1].
2. Noise level [Table 2]
3. Super low noise
Low noise is one of Zaward’s fan characteristics, especially the Golf fan series. Its low flow turbulence of perfect 3-dimension impeller shapes and low flow resistance dimples surface design make more quiet rotating and more effective heat dissipation.
4. How to reduce the noise level
Refer to the heat dissipation of electronic and electric equipments, list below the causes made the noise and the way to reduce it.
4.1 System impedance The airflow resistance from the computer systems or equipments is called system impedance. For blow-in system, the total area measure of the air outlet needs to be 20% ~ 40% larger than that of the air intake. As for the blowout system, the total area measure of air intake needs to be 20% ~ 40% larger than that of the air outlet. If the air outlet of blow-in system or the air intake of blow-out system is too small, it brings more system impedance, and consequently poorer heat dissipation. If increasing the fan speed to enlarge the airflow, the noise level will be higher. System impedance can be reduced and the noise level will be lowered at the same time from proper adjustment of the area measure of air intake and air outlet, and also do proper arrangement of the system’s components. But, if the air outlet of blow-in system is too big, or the air intake of blow-out system is too big, the airflow speed will be too low. Thus, it is unable to bring out the heat of part components, nor to work effective dissipation. The bigger space inside the system makes the smaller flow impedance. The heat dissipation is better if the heat source components located on the way of airflow.
4.2 Flow turbulence The vertical barrier and sharp angle shapes in the passage of airflow will cause noise. Therefore, we need to prevent from vertical obstacle or angle shape, particularly on the crucial air intake and outlet areas where having higher air speed. Zaward’s fans got curve-edged design on the air intake and outlet to minimize the flow turbulence enabling to accelerate the airflow blowing in and out
4.3 Fan speed and size The fan with high speed makes higher noise level than that with low speed. Thus, it is recommended to use the fan with low speed if possible. With the same airflow, the fan in bigger size and lower speed is quieter than that in smaller size and higher speed.
4.4 Temperature rise Within a system, the airflow required from cooling is with inverse ratio against allowable temperature rise. Slight temperature rise reduces airflow tremendously. Thus, if lower slightly the limit of allowable temperature rise, the airflow is lowered and the noise level is reduced significantly
4.5Fan fixing components Components design of fan fixing relates to the system noise level. Thus, it’s essential to selects anti-vibration materials while fix the fan or assembly the fan on your chassis. If special low noise design is required, please contact our sales department.
1. Flow rate and static pressure
The measurement of flow rate and static pressure is easily affected with various factors. So, we need to use precise measurement instruments. Zaward’s instrument of automatic pneumatic tunnel apparatus is made in accordance with the international standard of AMCA210. Its measuring range covers flow rate 3 ~ 250 CFM, static pressure 0 ~ 60 mmAq. See [diagram 2]
2. Test theory: Law of Continuity
The continuity of flow equation is one of the major tools of fluid mechanics, providing a means of calculating velocities at different points in a system. For steady flow in a stream tube, having changeless cross-sectional area over any given cross-section, the mass of flow per unit time will be equivalent. Then: ρνS=Constant. Suppose there are two different sections A and B in the stream tube. At section A the cross-sectional area is S1, the velocity of flow is ν1 and its density is ρ1 At section B the cross-sectional area is S2, the velocity of flow is ν2and its density is ρ2. Then: ρ1ν1S1=ρ2ν2S2=Constant Since the flow can be considered as incompressible, so that ρ1=ρ2, then: ν1S1=ν2S2
2.1 Adjust the auxiliary blower makes static pressure come to zero. It gets the maximum flow rate point Qmax.
2.2 Shut down the auxiliary blower makes the flow rate come to zero. It gets the maximum static pressure point Pmax.
2.3 Adjust different flow rate points of blower to get PQ curve. To measure different flow rate points needs to adjust the nozzle’s diameter. The pressure difference caused between the front and rear chambers of nozzle. Its pressure difference measured from the instrument needs to transfer from the computer. Use the law of continuity, the variety of pressure difference can achieve equivalent air speed and flow rate (flow rate = air speed x nozzle’s section area).
2.4 Flow rate conversion table [table 3]
1. The less electric current, the lower power consumption and consequently the less temperature rise.
2. Operating current refers to the current value when the fan starts operating around one minute and the fan speed stays stable.
1. Rated voltage refers to the normal specific voltage written on the fan approval sheet
2. Operating voltage refers to the voltage allowable on the fan approval sheet. Use the fan within the operating voltage.
3. Starting voltage refers to the lowest running voltage required for the fan.
1. Input power is measured under the rated voltage. P = IV =I x IR
2. Actual current used times voltage supplied equals to the power consumption. Its unit is W.
There are many ways to measure speed, such as using oscilloscope, stroboscope, infrared, or fan’s open collector output as shown on diagram 4 using a third lead wire to output a square wave.