centrifugal fan flow and presure

[pardal]

Please if this is not the proper Forum , redirect me to it.

I got a centrifugal blower or fan that is broken.
To be more clear it have the same shape of those used at window airconditionig appliance at the evaporator side.
It is 230 mm diameter , 85 blade wide , simple end (only one side open) , it have 45 foward blades.
Original it run at 1400 to 1500 RPM. Paired with other similar, but mirrored
Motor is 2 HP.

My concern is what other data I need to know the flow and pressure drop that this fan can develop, and after it how it can be stimated or calculated.

A drawing is aviable .
Ask for it at

k281969@hotmail.com




Pardal


Pardal

 

[psychro]

Try by contacting the fan manufacturer to obtain test data matching your fan specifications or
just check the airflow requirements for the load and the pressure drop of the system to estimate the fan original requirements. This is not exact because the conditions of the system may have changed with time. Good Luck.

 

[lilliput1]

If this is for work or comercial application, my recommendation is to replace it with new. If for personal use, it is up to you. I did fixed the blower on my Lennox unit by using superglue to reattach the scroll to the hub. The scroll was lock crimped to the hub. eventually this worked loose. Trick is making sure the scroll is aligned back per the original by noting the original blade marks on the hub. If not properly aligned you will end up with an unbalanced fan. The superglue, being light would not affect balance considerably provided you have indexed the scroll to its proper position. Also clean out all dirt that may have stuck to the fan over time, prior to gluing. They would interfere with the balance. My unit run well after that. I did eventually have to replace it even though it was still working, because it's compressor draws a lot of power. The replacement Rudd unit cut power about in half but it's indoor fan was noisier than the Lennox.

 

[pardal]

This fan is broken , I need to replace it , but no any local vendor can say me the data I want , or if he can, it want to sell what he sell.

The simple task I want to know, is if there is any method or formula to know 2 or 3 particular point that this fan could meet, the fluid is air.

The only constraint is speed about 1300 to 1500 RPM .

I'm not worry about hp, I can fix any needed motor.

What I need to know is what flow and head pressure could it deliver.

Other fact is that I need to suit this array with a filter , and as I can not know the flow I can not size the filter.












Pardal

 

[mdonner]

I hope you have the blower housing too, cause what you describe is the impeller. Without the housing you do not have a blower.
What is broken in your blower?
Sorry, no formulas or other calculation info.
Window AC units will deliver about 300 cfm per TR (12,000 btu/hr), and from the dimention you supplied I'd gess it is 500-600 cfm. Usually static pressure is very low (0.1" W.G.).
Filter sizing is mostly about noise and filtration efficiency. For such a small unit price difference is neglectable, and you may calculate it for 300 fpm air speed, so you need surface area of 2 sq. ft. at worst case.
(Filter area is limited by unit housing, and you usually get lower air speed through filter, which is better).

 

[pardal]

Hi Mdonner:

Of course I have the housing.

The impeller is all broken , it only have 15 of 45 blades.
It was damaged because the oil mud disbalanced it , and it ran until was destroyed.

I can not believe tha there is no formula or empiric way to get the flow and head pressure aviable.

Thanks againg.






Pardal