Previous in Forum: Current   Next in Forum: Induction Motor
Close
Close
Close
9 comments
Rate Comments: Nested
Member

Join Date: Jul 2006
Posts: 5

Can We Calculate the Air-Flow?

02/22/2008 4:45 AM

Hi all, In case that we just know only the capacity of a machine like the powder-coating one (baking process) for e.g it's 7.5KW, and other basic info for e.g votalge 380V-3phases, 60Hz. How can we calculate the air-flow for this machine?

Register to Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

"Almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, vote them!
Guru
United Kingdom - Member - Olde Member!! Engineering Fields - Instrumentation Engineering - New Member

Join Date: Jul 2006
Location: Dunstable, England
Posts: 2821
Good Answers: 45
#1

Re: Can We Calculate the Air-Flow?

02/22/2008 8:32 AM

Huh???

Could you re-phrase that... it is a question isn't it?

__________________
A little knowledge is a dangerous thing - Googling is far worse!
Register to Reply
Active Contributor

Join Date: Jun 2007
Location: Los Angeles, Ca.
Posts: 15
#2

Re: Can We Calculate the Air-Flow?

02/22/2008 12:28 PM

Sir:

Given enough information, we can calculate almost anything. Whether it's true or not is a matter of the quality of the information.

Register to Reply
Power-User
Engineering Fields - Electrical Engineering - New Member

Join Date: Aug 2007
Location: Toronto
Posts: 239
Good Answers: 9
#3

Re: Can We Calculate the Air-Flow?

02/23/2008 1:26 AM

Insufficient information. With what you presented, we can just as easily calculate the weight, colour and physical dimensions. If I told you I was a 50 year old man, how would you calculate my annual salary?

Please be more specific. Does this machine have a fan? What type, what size blades, at what speed, etc.

Register to Reply
Guru

Join Date: Jun 2006
Posts: 501
Good Answers: 8
#4

Re: Can We Calculate the Air-Flow?

02/23/2008 6:59 AM

Does the 7.5 KW include the power to the heater elements?

The blower - does it have a high volume rotor? high pressure rotor?

The blower should have the CFM on the name plate. This is the maximum flow at the rated pressure.

How large are your exhaust ports? Do you use the blower to only provide circulating air? Is there an exhaust.

Is your heat electric or fuel fired?

How large is this furnace (cubic feet)?

Register to Reply Score 1 for Good Answer
Member

Join Date: Jul 2006
Posts: 5
#6
In reply to #4

Re: Can We Calculate the Air-Flow?

02/24/2008 2:50 AM

Thanks for your all comments.Yes there is a lack of info given to my raised question, this machine is heat by electric and the exhaust port is by 2*150mm Dia.The reason i asked this,it's because in fact this machine is custom-made one and there is nothing else that i could have except : there is not enough exhaust ducting from the machine to out side that caused the room to be more hot and dust

Hope that i could come back and give you all more info within the next coming days

RGDS

Tommy

Register to Reply
Guru
Engineering Fields - Piping Design Engineering - New Member Egypt - Member - Member since 02/18/2007

Join Date: Feb 2007
Location: Cairo, Egypt
Posts: 1733
Good Answers: 248
#5

Re: Can We Calculate the Air-Flow?

02/23/2008 10:07 AM

By knowing the type and model of the machine, please refer to the catalogues and/or specifications of the manufacturer or contact directly to the supplier.

In a lot of cases, the machine made by a such manufacturer may be differs in its output if compared with a similar machine produced by another manufacturer which consumes the same power.

__________________
It is better to be defeated on principles, than to win on lies!
Register to Reply
Guru
United States - Member - New Member Engineering Fields - Power Engineering - New Member

Join Date: Sep 2006
Location: California, USA, where the Godless live next door to God.
Posts: 4665
Good Answers: 804
#7

Re: Can We Calculate the Air-Flow?

02/24/2008 8:51 PM

You COULD theoretically determine air flow by monitoring the motor power, but you would need the fan curves. If you can extract a manufacturers name and model number from the fan they should have that information available. Their chart will show air delivery at a given HP or kW input on a curve, so if you have a kW meter on the motor, you can extrapolate how much air the fan is delivering. It will not be exact because restrictions in the ducting etc. will decrease that, but it could give you a general idea.

By the ay, your kw metering would need to be only on the motor circuit, not the entire machine.

__________________
** All I every really wanted to be, was... A LUMBERJACK!.**
Register to Reply
Power-User

Join Date: Aug 2007
Location: Bhopal India
Posts: 234
Good Answers: 5
#8

Re: Can We Calculate the Air-Flow?

02/25/2008 9:20 AM

It all depends upon the type of Fan....but a good design should give 13000 cubic feet per minute per eKw.

So in your case it would be 97500 cfm.

Now this assumes 7.5kw is the motor rating of fan.

It may have heaters and other load, just check the motor KW of the fan.

Cheers,

__________________
He must be very ignorant as he answers all the questions he is asked. Voltaire
Register to Reply
Power-User

Join Date: Dec 2006
Location: Boston, MA
Posts: 265
Good Answers: 4
#9

Re: Can We Calculate the Air-Flow?

02/25/2008 11:13 AM

My powder coating oven has "no" air flow. It has a small vent to allow the gasses to vent outside through natural convention. I keep it closed until cool down.

I'd imagine that a vent fan or forced convection would be a bad thing in a powder coating oven. The powder is not fixed well and will blow everywhere. The powder can ignite too. I'd imagine you'd have an explosion (in grain silo fashion) if the powder became airborne confined within the oven.

On the other hand the room you do your powder coating in should be ventilated as the fumes are mildly toxic. Venting your room should cure your temp issue. See the rated CFM on the fan and use it in conjunction with your room dimensions to calculate your air exchanges per hour. My garage vents at 4 air exchanges per hour.

Register to Reply
Register to Reply 9 comments

"Almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, vote them!
Copy to Clipboard

Users who posted comments:

Abdel Halim Galala (1); chaterpilar (1); Electroman (1); Graebeard (1); Heath (1); jmart23 (1); JRaef (1); Pretendgineer (1); TommyofVN (1)

Previous in Forum: Current   Next in Forum: Induction Motor

Advertisement