slowing down a mag drive 2400...if possible

[awk]

 

[rallysman]

He added a bypass tee so he wont be burning it up and quicker than normal.

From the sound of it the overflows are not large enough or there is a restriction somewhere.

 

[Tongue33]

If your pump is draining your sump it is the drain to the sump that is too small YOUR overflows are not pulling enough water into the sump to facilitate the mag 24 Your drains in my opinion are constricted

Exactly

 

[wright4lfe]

i think i'm just going to hang on to the 2400 (even though its on the for sale/trade forum, if no bites in the next day or two i'm going to pull it off) and get a lower output pump. i don't have the time/energy to make bigger overflows on this tank after work i've already done. i'll probably just go with a smaller pump and and XP5 or two.

but i'lm still going to post pics of the setup...

 

[Volenti]

If you restrict the pump it will try and stop the rotor because of the back pressure and it will take more amperage to run the motor and since energy has to change into other forms you will get heat and power.


I was reading the instructions that came with my linear piston air pump and it says that the more resticted the output is the more amps the motor will draw and the hotter the motor will get so it is better to let it move the air then to build pressure.

When talking about water pumps this only matters in positive displacement pumps,(like your piston air pump) there it is a big issue and can easily break things/bust pipes, however with centrifugal pumps the only thing the pump is actively doing is spinning the water in the impeller chamber, it's the centrifugal force of the water pressing against the impeller chamber walls and eventually escaping via the outlet that cause water to flow. If you block the outlet completely the pump will happily spin the water in the impeller chamber untill the cows come home, and it will draw less current doing so, I've tested it.

 

[repair]

When talking about water pumps this only matters in positive displacement pumps,(like your piston air pump) there it is a big issue and can easily break things/bust pipes, however with centrifugal pumps the only thing the pump is actively doing is spinning the water in the impeller chamber, it's the centrifugal force of the water pressing against the impeller chamber walls and eventually escaping via the outlet that cause water to flow. If you block the outlet completely the pump will happily spin the water in the impeller chamber untill the cows come home, and it will draw less current doing so, I've tested it.

Interesting.... I will have to test it.... Thanks

 

[johnptc]

When talking about water pumps this only matters in positive displacement pumps,(like your piston air pump) there it is a big issue and can easily break things/bust pipes, however with centrifugal pumps the only thing the pump is actively doing is spinning the water in the impeller chamber, it's the centrifugal force of the water pressing against the impeller chamber walls and eventually escaping via the outlet that cause water to flow. If you block the outlet completely the pump will happily spin the water in the impeller chamber untill the cows come home, and it will draw less current doing so, I've tested it.

except if its choked to far the water will heat up from friction...

 

[johnptc]

You are confusing Work and Energy. Work is dependent on displacement but energy is not. You can't use the Principle of Work and Energy on a restricted pump. It violates one of the laws of thermodynamics (can't quote it off hand). (In other words, the math will fail.)

the work done is the energy input ( no friction)


I can see the engineer or physicist in there trying to get out.

A compressed spring is a good analogy. Compressing the spring requires both work and energy. ( ENERGY=FORCE*DISTANCE= WORK DONE = (1/2kX*X)To keep it compressed by hand, you are not doing anymore work (not laymans definition) but you are still consuming energy. ( not if you sit on the spring to keep it in place)

except water does not compress and we can take the piping as rigid...this is why hydraulic systems are so common in heavy machinery

The pressure created by the pump exerts force on the walls of a pipe. Energy is required to maintain that force. (except if you close the valves the pressure remains high with no work being done or energy being used....like sitting on the spring)The seemingly easy way to find the energy is to use Statics principles since it can be viewed as no motion as the flow approaches zero. In Statics applications, the sum of all forces equals zero. Unfortunately, if used in the wrong applications false zeros will result as your conclusion. You can't use Statics principles for Thermodynamics problems.

 

[Bud8Fan]

johnptc is 100% correct. They use the most energy when running wide open at zero head. Centrifugal pumps that is.

At the chemical plant I used to work at each centrifugal pump had an amp meter at each station. Throttle back the discharge and the amperage goes down. Open it up to get more flow and watch the amperage climb.

Not to be confused with "positive displacement" or "reciprocating" pumps which should NEVER be throttled back on the discharge. These are the types of pumps that pump gases like your air pumps.

Throttle back one of these pumps and watch the amperage skyrocket then listen for the relief valve to blow.

And I just saw Volenti's post. Also 100% correct.

 

[CHOMPERS]

You make a good arguement I can't counter it. I am almost convinced I am going to have to play with a pump and ampmeter now