slowing down a mag drive 2400...if possible

[repair]

why would it use more energy if its doing less work ???

centrifugal pumps use the most current when running wide open and moving lots of water and very little when pumping near their max head height and doing very little work.....

there is some wasted energy as heat from viscous friction but i don't believe it will compare to the energy needed to move the water...........

2 cents.

That's not true..... moving water is easy building pressure requires a lot more energy.

It's just like a 10 speed bike..... you can be in 10th gear on a level surface= (moving water) it's not too bad but if you have to go up a hill= (build pressure) it takes more effort=(energy)


This can be confusing.

 

[dr_sudz]

That's not true..... moving water is easy building pressure requires a lot more energy.

It's just like a 10 speed bike..... you can be in 10th gear on a level surface= (moving water) it's not too bad but if you have to go up a hill= (build pressure) it takes more effort=(energy)


This can be confusing.

This sounds like a squabble, but the easiest way to ensure long life of a pump is just to T the return back to the sump and have a flow valve there to allow for bleed off. That way the pump is running full tilt but with out putting any unnessissary strain on your pumps.

 

[repair]

This sounds like a squabble

It's all good, were aren't upset we are just having a discussion.

I'm all about learning.... if I'm wrong I want to know.

 

[wright4lfe]

like i said, thats why i love this site. we've got guys with experience in just about every aspect of this hobby more than willing to help. it doesn't get much better.

 

[repair]

like i said, thats why i love this site. we've got guys with experience in just about every aspect of this hobby more than willing to help. it doesn't get much better.

If I can help someone else avoid some of my mistakes then I'm happy.

I have a lot of experience with pumps and hydraulics and if I'm wrong I want to know.

I learn new things everyday..... alot of times from this forum.

 

[dr_sudz]

so what is the verdict then? whether you sinch down before the pump or after is that not both putting a strain on your pump or no?

 

[johnptc]

That's not true..... moving water is easy building pressure requires a lot more energy.

It's just like a 10 speed bike..... you can be in 10th gear on a level surface= (moving water) it's not too bad but if you have to go up a hill= (build pressure) it takes more effort=(energy)


This can be confusing.

since water in not compressible it takes no energy to build pressure

to move water you have to add energy to the water to get it moving ( kinetic energy ) like 1/2 m v*v at zero head no
change in height

the pump that pumps 100 gpm a zero head does a lot more work the same pump pumping water at 20 feet head at 5 gpm

lifting water requires some energy ( mass*gravity*change in height) to lift and a tiny amount of energy for kinetic as the flow is very low and KE is proportional to v*v

it does seem confusing

but this is my understanding but like repair i love to learn and certainly can be wrong in my beliefs

 

[johnptc]

so what is the verdict then? whether you cinch down before the pump or after is that not both putting a strain on your pump or no?

never ever restrict the flow to a centrifugal pump !!!

it can create cavitation and ruin the pump.....

THIS I AM SURE OF !!!!!

 

[repair]

since water in not compressible it takes no energy to build pressure

to move water you have to add energy to the water to get it moving ( kinetic energy ) like 1/2 m v*v at zero head no
change in height

the pump that pumps 100 gpm a zero head does a lot more work the same pump pumping water at 20 feet head at 5 gpm

lifting water requires some energy ( mass*gravity*change in height) to lift and a tiny amount of energy for kinetic as the flow is very low and KE is proportional to v*v

it does seem confusing

but this is my understanding but like repair i love to learn and certainly can be wrong in my beliefs

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.

 

[repair]

In a transmission pump you have a pressure regulator valve and it's job is to keep the pressure constant..... if you increase the pressure that the pump builds the engine will have produce more torque to produce the aditional pressure so they keep the pressure as low as they can to help improve gas milage.

The way that a pressure regulaor valve works is that when the pressure reaches the desired pressure it vents the additional volume and pressure back into the sump.

That is how 99% of all pumps worked untill they came up with a variable diplacement pump using a rotor and vanes and a variable pump slide, in this new design the pump will only produce the amount of pressure that it needs and then the slide will move and in effect make the pump smaller so it produces less volume at the pressure it needs and has less back pressure so it needs to vent less excess volume into the sump.

This is the most efficent pump design but I have never seen it used in aquarium pumps.