Can We Calculate the Air-Flow?

Huh???

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

Sir:

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

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.

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)?

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

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.

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.

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,

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.