fan increases the amperage. I just tried this with an amp gauge in the circuit and I know the statement to be true but if reducing the amount of fluid moved works in the pump why not the fan?
2007-05-09 15:05:53 · 6 answers · asked by Anonymous in Science & Mathematics ➔ Engineering
fan increases the amperage. I know the rducing the amount of fluid moved in the pump reduces the power required and even checked it with a meter. Close the discharge on the pump, amperage goes down. I tried it on a fan and the oppisite happens. Why?
2007-05-09 15:11:25 · update #1
compression, or lack there of in the case of the pump is the answer. and the problem delt only with closing the discharge of the fan or pump. I tried to pick the best answer but it hasnt been 4 hours. Thanks all
2007-05-09 17:28:58 · update #2
Compression! AIr is compressable and liquid is not (my guess is water). When you throttle down on the fan outlet your compressing air - still moving the same amount with a resistance to flow. When you throttle down on the pump discharge you're moving less water. Less work = less power used.
2007-05-09 15:39:33 · answer #1 · answered by onparadisebeach 5 · 1⤊ 1⤋
Centrifugal fans like centrifugal pumps have generally rising horsepower characteristics. That is, as the system resistance decreases and the volume increases, the horsepower likewise increases.
But not all fans are centrifugal. Axial flow (propeller) fans have an overall decreasing horsepower characteristic. Those horsepower curves are somewhat lazy "S" shaped and are maximum at no flow.
One exception within the centrifugal category is the backward inclined bladed fan which has a horsepower that peaks about in the middle of the volume range and then starts back down.
2007-05-09 15:53:35 · answer #2 · answered by Bomba 7 · 0⤊ 0⤋
While you were using a centrifugal pump, I'd say there was a 99.999% chance that you weren't using a centrifugal fan. If both had been of that nature, the physics of both would agree in terms of power required if their respective "fluid" flows were restricted, and you should have seen similar changes in current in both cases.
Fans of different construction have very different responses to restricted flow. A blade style (axial flow) fan will increase in speed when flow restricted, and current will rise. I'm guessing that's what you saw.
Find yourself a centrifugal (squirrel cage) fan and try the same experiment by cutting off its intake. You'll be surprised.
Blade style fans only work well at low static pressures. Centrifugal fans can develop a great deal of static pressure.
2007-05-09 15:32:24 · answer #3 · answered by C Anderson 5 · 1⤊ 1⤋
Not sure what's going on with the fan. But the power is a function of the pressure difference and the lbs of material being moved.
In your case it is possible that as you restricted the flow the pressure difference increased more than the flow was reduced.
2007-05-09 15:59:48 · answer #4 · answered by Roadkill 6 · 0⤊ 0⤋
With the air, reduce the intake of the fan. when you are moving air and you reduce the out put of the fan at the outlet the air is being compressed. this is why the load is increased. The fluid can not be compressed it just stops moving.
2007-05-09 15:29:14 · answer #5 · answered by unpop5 3 · 2⤊ 0⤋
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2016-12-17 08:46:46 · answer #6 · answered by hergenroeder 4 · 0⤊ 0⤋