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vitthal
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Join Date: Apr 2014
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Calculation of CFM of a Blower

04/03/2014 3:06 AM

Present Blower Specifications

120 cfm

65 mm of static pressure of water column

3000 rpm

3 phase , 0.5 HP

Required new Blower specification with following data

what is the cfm of the new blower with this specification ?

single phase 0.2 HP and 1350 rpm

If posssible please give the formula for the calculation.

Thanks
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IdeaSmith
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#1

Re: Calculation of cfm of a blower

04/03/2014 3:50 AM

This is home work! We no do homework here!

If it was a requirement then the replacement blower would have the same capacity as the outoging one!

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Codemaster
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#2
In reply to #1

Re: Calculation of cfm of a blower

04/03/2014 7:17 AM

Whether it's homework or not, it's a ridiculous question. He gives us no clue what he's trying to achieve.

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IdeaSmith
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#3
In reply to #2

Re: Calculation of cfm of a blower

04/03/2014 8:43 AM

Because it is a question from a book and not for an achievement!

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Codemaster
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#9
In reply to #3

Re: Calculation of cfm of a blower

04/03/2014 4:12 PM

If it is homework, it's rubbish whoever set it, as it's not at all clear what the question is.

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ozzb
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#4

Re: Calculation of CFM of a Blower

04/03/2014 9:22 AM

Whether it's home work or not. It's best you educate yourself. Instead of us asking for all the information needed to make the calculations for you.

http://www.cincinnatifan.com/catalogs/EngData-203-internet.pdf

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Kilowatt0
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#5
In reply to #4

Re: Calculation of CFM of a Blower

04/03/2014 9:54 AM

I love the links and info I get here on CR4! Thanks for that link. But I'm gonna need a bigger hard drive!

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Wal
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#12
In reply to #5

Re: Calculation of CFM of a Blower

04/03/2014 11:45 PM

I gave up downloading information and saving links a while back. Let it be stored on the cloud and refer to it as required....if I forget where on the cloud to look and searching draws a blank I refer back to the CR4 blitherfest.

But yeh...just because one isn't adding constructively to a commentary doesn't mean that one isn't learning, even if it's learning what you don't know that you don't know...the "unknown unknowns".

Have a good weekend.

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lyn
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#6

Re: Calculation of CFM of a Blower

04/03/2014 10:01 AM

45
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IdeaSmith
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#7
In reply to #6

Re: Calculation of CFM of a Blower

04/03/2014 10:33 AM

42?

Just to be correct with the meaning!

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lyn
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#8
In reply to #7

Re: Calculation of CFM of a Blower

04/03/2014 10:43 AM

No. 42 has an actual meaning. I chose a meaningless number as the answer to a meaningless question.
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phoenix911
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#14
In reply to #8

Re: Calculation of CFM of a Blower

04/04/2014 11:21 AM

Meaningless, how about dimensionless number....... 4532 Re

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PWSlack
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#10

Re: Calculation of CFM of a Blower

04/03/2014 4:33 PM

Well, if the static pressure on the delivery side of the compressor is the same, then given that the motor power is 40% of the original one then the achievable flowrate will be around 40% of the original one, or 48 cfm. Does that help?

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#11

Re: Calculation of CFM of a Blower

04/03/2014 4:36 PM

Power consumed is proportional to Q ΔP / η. There is a trade-off between the first two terms.

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dhayanandhan
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#13

Re: Calculation of CFM of a Blower

04/04/2014 1:19 AM

Dear Mr.Vitthal,

Your question should have more data. You have asked "

what is the cfm of the new blower with this specification ?

single phase 0.2 HP and 1350 rpm"

You have not confirmed what is the static Pressure for the new blower. The CFM depends upon the Static Pressure and Efficiency of the Blower.

There is one thumb rule, (when speed is 1440 rpm) which is approximate value

H.P = (V x d)/600, where V = cfm at NTP, d = draught in inches of water. In this formula variation of efficiency is not considered.

Beat thing is go by Design aspect, by engaging an expert in this field.

DHAYANANDHAN.S
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Codemaster (2); dhayanandhan (1); IdeaSmith (3); Kilowatt0 (1); lyn (2); ozzb (1); phoenix911 (1); PWSlack (1); Tornado (1); Wal (1)

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