Fan total pressure enough or not?

In summary, the conversation discussed designing an exhaust system for a wood working facility. They determined the necessary airflow and total pressure drop, but realized their current fan may not be suitable due to the pressure loss caused by the added air cleaning device. They also asked for advice on how to increase the fan's total pressure and how to calculate the necessary extra filter area.
  • #1
supernova1387
31
0
Dear all

I'm designing an exhaust system for a wood working facility. Please correct me if I'm wrong as I'm new to this industry:

The system needs about 4.8 m^3/s airflow (with main duct velocity of 20m/s and branch velocity of 23 m/s). The total pressure drop due to the ducts and fittings up to fan inlet is about 1500 Pa. For some reasons, the air cleaning device (bag house) has to be installed on the outlet side of the fan . I already have a fan which can handle this flow rate but the total pressure of the fan at this flow rate is about 1800 Pa according to its fan curve. I obtained the fan curve myself based on the AMCA 210-07 standard and pitot traverse method. I believe if I add the pressure loss due to the bag filter, the fan is not suitable. If I assume the bag filter has the pressure drop of about 1500 Pa after the dust cake has been created, I need a fan which can handle total pressure loss of 3000 Pa @ 4.8 m^3/s which means the fan I have is not suitable. (correct me if I'm wrong)

Also please help me with these 2 questions:

1- Given that the flow rate is enough for the job, how can I increase the fan total pressure ? (is it only through increasing rpm?)

2- If I increase the filter area, does it decrease the pressure loss? If yes, how do I calculate the amount of extra filter area?

Any hint or advice is appreciated. I'm absolutely stuck :confused:

Thanks in advance
 
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  • #2
1- Given that the flow rate is enough for the job, how can I increase the fan total pressure ? (is it only through increasing rpm?)
For a given fan, yes. What else could you change?
2- If I increase the filter area, does it decrease the pressure loss? If yes, how do I calculate the amount of extra filter area?
Probably, as the flow rate per area would go down. How much? That depends on the geometry. Is more frequent cleaning an alternative?
 

1. What is fan total pressure?

Fan total pressure is the measure of the total energy added to a fluid by a fan. It includes both the static pressure and the velocity pressure.

2. How is fan total pressure calculated?

Fan total pressure is calculated by adding the static pressure (the pressure exerted by a fluid at rest) to the velocity pressure (the pressure exerted by a fluid in motion).

3. Why is fan total pressure important?

Fan total pressure is important because it indicates the amount of energy added to a fluid by a fan. This can affect the performance and efficiency of a fan system.

4. What factors affect fan total pressure?

The factors that affect fan total pressure include fan speed, fan blade design, air density, and the resistance of the system being ventilated.

5. How can I determine if the fan total pressure is enough?

The fan total pressure should be enough to overcome the resistance of the system being ventilated and provide adequate air flow. This can be determined by calculating the required fan total pressure based on the system's resistance and comparing it to the actual fan total pressure. If the actual fan total pressure is greater than the required fan total pressure, then it is enough.

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