What Happens If You Block a Fan with a Drag Tube?

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Discussion Overview

The discussion revolves around the effects of blocking a fan with a drag tube, specifically focusing on the implications for motor load, heating, and airflow dynamics. Participants explore theoretical scenarios related to fan operation and motor performance.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions the effects of trapping a drag tube before a fan, asking whether the motor would heat up or experience a decrease in load.
  • Another participant emphasizes the need for more information regarding the size and orientation of the drag tube and fan to provide a reasonable response.
  • A subsequent post clarifies that if the fan is enclosed in a tube that prevents new air from being drawn, it raises questions about whether the motor load would increase or decrease, and why there are claims that the motor could break.
  • Another participant shares an observation from a different context, noting that blocking the intake of a vacuum cleaner leads to an increase in motor speed but a decrease in current draw, while cautioning against prolonged operation in this state due to potential overheating.

Areas of Agreement / Disagreement

Participants express differing views on the mechanics of fan operation when blocked, with no consensus reached regarding the specific outcomes of blocking the fan with a drag tube.

Contextual Notes

Participants highlight the importance of specific conditions such as the size of the drag tube and fan, as well as the implications of airflow on motor cooling, which remain unresolved.

EngineerAhmad
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Hi every body..
Say you trapped the drag tube before a fan, what would happen then?
Will the Amber decrease?
Will the motor be heated ?
Why?

Please I need reasonable replies ..
 
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EngineerAhmad said:
Hi every body..
Say you trapped the drag tube before a fan, what would happen then?
Will the Amber decrease?
Will the motor be heated ?
Why?

Please I need reasonable replies ..
It is not possible to give a reasonable reply without knowing more about the size of the drag tube, its orientation, the size of the fan.

What does one mean by trapping the tube before the fan?

What amber?

A motor would heat if there was more mechanical resistance to it. Most motors are designed for a particular speed.
 
Say the fan is put in a tube which have the same size of it, then we trapped the tube before this fan, that no new air can be drawn.
Would the motor have less load (then the Amber of the fan motor will decrease) or the motor would be heated?
I.e: Would the load increase or decrease and why do everybody say the motor would break up?
 
Oh, I get it.

You can't really do this with an ordinary fan, since the enclosure which keeps you from accidentally contacting the blades allows enough space for air to circulate past. But, you can do this with a vacuum cleaner; if you put your hand over the intake, you can actually hear the result: the motor speed increases, since there is less drag on the impeller. In the meantime, however, the current draw (the word you want here is not "amber" it's "amperage) actually decreases. You don't want to run the motor for very long in this condition, though, because it is designed to be cooled by the airflow. Eventually the windings would overheat and fuse and the motor quits.
 

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