Blower
Converts shaft rotation into a pressurised airflow, exchanging some volumetric flow for static pressure compared to a flat axial fan, so it can blow air through long ducts, dense heat-sink fins, or HEPA filters that would stall an axial.
A brushless DC or induction motor spins a many-bladed cylindrical impeller at 2 000–20 000 rpm. Air enters axially through the inlet, gets accelerated radially by the blade tips, then is collected by the volute (scroll) and decelerated to recover dynamic pressure as static pressure. Forward-curved blades give high flow at modest pressure; backward-curved give higher pressure and efficiency.
In plain terms
Like a hamster-wheel inside a snail shell — the cage flings air outward by centrifugal force, and the spiral housing redirects that radial flow out a single tangential nozzle.
Why designers use it
- Moving air against a system pressure drop where the selected blower's operating curve fits the requirement.
- Arranging inlet and outlet airflow to suit the enclosure.
- Controlling speed when the chosen model provides a compatible control input.
Best for
- Server cooling
- CPAP machines
- HEPA ducts
Key specifications
- Operating limits: Check the exact manufacturer's datasheet (A family name does not establish voltage, current, temperature or timing limits.)
- Pin assignment: Match the complete part and package code (A similar name or function does not guarantee the same wiring.)
- Mechanical fit: Use the exact package drawing (Check pad layout, dimensions and viewing direction before building.)
When not to use it
- When the required airflow and system pressure do not intersect the product's usable operating curve.
- When its measured noise, power, temperature or mounting requirements do not fit the design.
Common mistakes
- Choosing from free-air flow alone while ignoring the filter, duct and heatsink pressure losses.
- Assuming a model's maximum static pressure and maximum airflow occur at the same operating point.
- Blocking the inlet or changing the mounting arrangement without checking the manufacturer's requirements.
- Assuming every blower includes PWM control, a tachometer or the same lifetime rating.
Where you will find it
- Sanyo Denki's San Ace C175 report compares airflow, pressure, power and sound under stated operating conditions.
- The report's PWM-control and life-expectancy data belong to the documented fan model and conditions. They do not establish the performance or safety of a medical ventilator or CPAP system.
A short history
A centrifugal blower turns the airflow from its inlet and directs it through an outlet, rather than moving it straight along the axis like an axial fan. Blowers are useful where the cooling path needs higher static pressure. The enclosure's flow resistance and available space help determine which arrangement fits.