Re: Centrifugal Fan Performace Curve
There's no information whatsoever from the manufacturer..
That's one crap fan manufacturer if he won't supply you with the power, speed, pressure, volume characteristic graphs for his fan!!
I need to obtain it in a practical way.
A long time since I did this. As I remember blank off the inlet and measure the pressure drop across the fan (with no flow). Then progressively open the inlet measuring the pressure drop and airflow, check the motor power (not current) as well. Eventually you will reach a point where your motor is on full power (unless your fan has a 'non-overloading' characteristic). By then you will have been able to get the pressure/volume/power characteristics.
..but the fan cannot operate over a 50% valve opening at suction because the fan motor amperage rises over its stablished limit..
Your fan/motor combination is not 'non-overloading'. To prevent overloading the motor you need a certain minimum resistance to limit the airflow and hence power.
Hope this helps, as I said it's been a while since I had much to do with fans. Someone else may give some better information.
PS, your company website brings a smile to this engineers face ..... ■
Re: Centrifugal Fan Performace Curve
thanks for your interest designer, but I didn't get the last part about the not "non-overloading" system, as I said it's not possible to operate over a 50% opening of the gate valve at suction because of the amperage rise on the fan's motor and the system shuts off at this condition. Also here's a simple drawing that shows the system configuration and the two measssuring points I have, if necessary I can make new ones but I need to be clear where the meassuring is gonna take place for each value, as in flow and pressure...
Attachments
fan configuration and messuring points (ZIP)
■
Re: Centrifugal Fan Performace Curve
A non-overloading motor/fan system is one where with the fan running with negligible system resistance you do not overload the motor driving it. (You don't have that!).
I might be tempted to pull the fan out of the system with just one length of ducting on the inlet and outlet.
Have the inlet pressure tapping between the valve and the fan inlet. Measure the outlet velocity averaged across the free end of the duct on the discharge side with some type of anemometer. The results will be somewhere handy without going through a full pitot static traverse. ■
Re: Centrifugal Fan Performace Curve
hello.
the power required for driving a shaft is proportional to fans cfm.then it is natural that when you open the fan valve motors amper increes.so i suggest you to by a strronger motor. ■
Re: Centrifugal Fan Performace Curve
Originally posted by sadeghsms
i suggest you to by a strronger motor.
The power requirement is a function of flow and pressure. The question is, how much flow and pressure does the system need? Why fit a larger motor if the system flow and pressure does not need it?? It will just result in capital expenditure and ongoing higher running costs. ■
Centrifugal Fan Performace Curve
Would anyone please explain to me how can I obtain a centrifual fan performance curve by in site tests? There's no information whatsoever from the manufacturer so I need to obtain it in a practical way... The fan is working to create vacuum in a conveying system...
Also there's something I want to know, the fan has a gate valve on the suction side and no valve restriction at discharge, but the fan cannot operate over a 50% valve opening at suction because the fan motor amperage rises over its stablished limit and the system shuts off. Could anyone explain why that happens? and what needs to be done to fix it? ■