𝗙𝗮𝗻 𝗦𝗲𝗹𝗲𝗰𝘁𝗶𝗼𝗻 𝗮𝗻𝗱 𝗦𝗶𝘇𝗶𝗻𝗴. 𝗪𝗵𝗲𝗿𝗲 𝗠𝗼𝘀𝘁 𝗛𝗩𝗔𝗖 𝗗𝗲𝘀𝗶𝗴𝗻𝘀 𝗚𝗼 𝗪𝗿𝗼𝗻𝗴
Fans are often treated as simple equipment.
In reality, fan selection decides airflow stability, noise levels, energy consumption, and motor life.
If you do not understand fan laws and fan c
𝗙𝗮𝗻 𝗦𝗲𝗹𝗲𝗰𝘁𝗶𝗼𝗻 𝗮𝗻𝗱 𝗦𝗶𝘇𝗶𝗻𝗴. 𝗪𝗵𝗲𝗿𝗲 𝗠𝗼𝘀𝘁 𝗛𝗩𝗔𝗖 𝗗𝗲𝘀𝗶𝗴𝗻𝘀 𝗚𝗼 𝗪𝗿𝗼𝗻𝗴
Fans are often treated as simple equipment.
In reality, fan selection decides airflow stability, noise levels, energy consumption, and motor life.
If you do not understand fan laws and fan curves, you are designing blind.
𝟭. 𝗧𝗵𝗲 𝗧𝗵𝗿𝗲𝗲 𝗙𝗮𝗻 𝗟𝗮𝘄𝘀 𝗘𝘃𝗲𝗿𝘆 𝗘𝗻𝗴𝗶𝗻𝗲𝗲𝗿 𝗠𝘂𝘀𝘁 𝗞𝗻𝗼𝘄
Flow vs Speed
Flow is directly proportional to RPM.
Increase speed by 20 percent and airflow increases by 20 percent.
Pressure vs Speed
Static pressure varies with the square of speed.
A 20 percent speed increase raises pressure by 44 percent.
Power vs Speed
Power varies with the cube of speed.
That same 20 percent speed increase raises power by nearly 73 percent.
This is why overspeeding a fan can instantly overload motors.
𝟮. 𝗕𝗿𝗮𝗸𝗲 𝗛𝗼𝗿𝘀𝗲𝗽𝗼𝘄𝗲𝗿 𝗖𝗮𝗹𝗰𝘂𝗹𝗮𝘁𝗶𝗼𝗻
BHP = (CFM × Static Pressure) ÷ (6356 × Efficiency)
Fan efficiency is not optional.
Forward curved fans typically operate at 60 to 70 percent.
Backward inclined fans operate at 70 to 85 percent and are far more energy stable.
𝟯. 𝗦𝗲𝗹𝗲𝗰𝘁𝗶𝗻𝗴 𝘁𝗵𝗲 𝗥𝗶𝗴𝗵𝘁 𝗙𝗮𝗻 𝗧𝘆𝗽𝗲
Forward Curved Centrifugal Fans
Best for low to medium pressure HVAC systems.
Compact and quiet but less efficient.
Backward Inclined Centrifugal Fans
Best for medium to high pressure systems.
Most efficient option with non-overloading power characteristics.
Preferred choice for commercial HVAC.
Axial Fans
Vane axial for medium pressure and high flow.
Propeller fans for low pressure exhaust and makeup air systems.
Excellent where space is limited but pressure capability is lower.
𝟰. 𝗥𝗲𝗮𝗹 𝗦𝗶𝘇𝗶𝗻𝗴 𝗘𝘅𝗮𝗺𝗽𝗹𝗲 𝗘𝗻𝗴𝗶𝗻𝗲𝗲𝗿𝘀 𝗙𝗮𝗰𝗲 𝗗𝗮𝗶𝗹𝘆
System requirement:
Airflow 10,000 CFM
Static pressure 3.0 in.w.g
Fan efficiency 75 percent
Calculated brake horsepower comes to approximately 6.3 HP.
With safety margin, the correct motor selection is 10 HP.
Now increase fan speed from 1000 to 1200 RPM.
Airflow increases to 12,000 CFM.
Pressure rises to 4.32 in.w.g.
Power demand jumps to nearly 11 HP.
This is how motors fail when fan laws are ignored.
Fan selection is not about choosing what fits on the drawing.
It is about respecting physics, efficiency, and long-term reliability.
Source: LinkedIn Page of Deepak Jha
There are many variations of passages of Lorem Ipsum available, but the majority have suffered alteration in some form, by injected humour.
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