How do you make a siphon faster?
- Thread starter Kreper3
- Start date
Excellent idea Amphiprion!
Here I hacked it into here:
Ok! For those of you willing to learn new things, and overturn past mistaken beliefs, I took a few hours and set up a demonstration to show the principal I have been explaining. Yes, I know it goes against the common understanding but that makes no difference against the actual facts. Let me remind you that for centuries we thought the Sun rotated around the Earth. We also thought the earth was flat...
To restate it: Throttling down a centrifugal pump does not harm it. Nor does it wear out its impeller. Nor does it over heat it. Nor does it damage its bearings, chemically or otherwise. This is absolutely true as long as the flow is not completely blocked.
Onward to the demo.
Here is the simple straight forward setup. It's a magnetic drive pump. An 1100gal/hr Little Giant pump made specifically for aquarium service.
A standard schedule 80 bulkhead was used and all piping and the ball valve are 1 inch which is the same as the pump inlet and outlet.
Close up of the pump.
A close up of the excellent wattmeter that was used.
The unrestricted bulkhead fitting.
Here we go. The system running with the ball valve wide open.
The pump is consuming about 100W of power doing maximum work, which is
moving about 1100gals/hr of water. Note the solid column of water returning to the tank. 103.8W
Now for some throttling. The ball valve is about half closed.
Notice the flow has dropped substantially. Notice also the power has not risen. The pump is not working harder.. It is working LESS. The power has decreased. 72.7W
Now the valve has been closed about 25%. Power has dropped still further.
57.9W
Here I have closed completely, blocked, the flow. Notice the power has dropped further yet! Of course it is not zero as there is a fan being run, bearing friction is present. Windage is occurring in the motor. There is resistance in the windings and there is some recirculation occurring in the pump head. Over time - minutes - the pump head would get warm. If there was the slightest trickle of water allowed thru the pump there would be no measurable heating as water can carry a great deal of heat away.
47.7W
I hope this helps you shed a very common misconception.
Get the closest sized pump you can.
If it over runs your return system, you can put in a valve and throttle the flow a little. Pay less to the power company and put less carbon into our atmosphere.
Or, divert to your sump which marginally adds a little more heat to your aquarium's water and stirs your water a little more.
It's your choice, but now you can make it based on facts.
Here I hacked it into here:
Ok! For those of you willing to learn new things, and overturn past mistaken beliefs, I took a few hours and set up a demonstration to show the principal I have been explaining. Yes, I know it goes against the common understanding but that makes no difference against the actual facts. Let me remind you that for centuries we thought the Sun rotated around the Earth. We also thought the earth was flat...
To restate it: Throttling down a centrifugal pump does not harm it. Nor does it wear out its impeller. Nor does it over heat it. Nor does it damage its bearings, chemically or otherwise. This is absolutely true as long as the flow is not completely blocked.
Onward to the demo.
Here is the simple straight forward setup. It's a magnetic drive pump. An 1100gal/hr Little Giant pump made specifically for aquarium service.
A standard schedule 80 bulkhead was used and all piping and the ball valve are 1 inch which is the same as the pump inlet and outlet.
Close up of the pump.
A close up of the excellent wattmeter that was used.
The unrestricted bulkhead fitting.
Here we go. The system running with the ball valve wide open.
The pump is consuming about 100W of power doing maximum work, which is
moving about 1100gals/hr of water. Note the solid column of water returning to the tank. 103.8W
Now for some throttling. The ball valve is about half closed.
Notice the flow has dropped substantially. Notice also the power has not risen. The pump is not working harder.. It is working LESS. The power has decreased. 72.7W
Now the valve has been closed about 25%. Power has dropped still further.
57.9W
Here I have closed completely, blocked, the flow. Notice the power has dropped further yet! Of course it is not zero as there is a fan being run, bearing friction is present. Windage is occurring in the motor. There is resistance in the windings and there is some recirculation occurring in the pump head. Over time - minutes - the pump head would get warm. If there was the slightest trickle of water allowed thru the pump there would be no measurable heating as water can carry a great deal of heat away.
47.7W
I hope this helps you shed a very common misconception.
Get the closest sized pump you can.
If it over runs your return system, you can put in a valve and throttle the flow a little. Pay less to the power company and put less carbon into our atmosphere.
Or, divert to your sump which marginally adds a little more heat to your aquarium's water and stirs your water a little more.
It's your choice, but now you can make it based on facts.
thanks for the demonstration, it's greatly appreciated, and overturns the notion of more power useage via less flow. I'm used to hydraulic and hydrostatic pumps; for which the opposite is true.
However, have you done any longevity tests with this method? I'd assume that in the case of the average centrifugal pump with less-than-maximum flow as it pertains to heat generated/energy used it should last longer.
However, have you done any longevity tests with this method? I'd assume that in the case of the average centrifugal pump with less-than-maximum flow as it pertains to heat generated/energy used it should last longer.
Hi mattmartindrift.
It's my understanding that the pumps do last longer but not greatly so. Not enough for there to be any kind of an economic aspect. You're absolutely correct that positive displacement pumps would definitely see more load with restrictions. Thankfully I don't think there are any in aquariums with the exception of peristaltic metering pumps.
In industry many, many pumps are throttled in the normal course of things. Often they are throttled to control downstream pressure. Agriculture throttles a ton because those large field irrigators often need a specific pressure to cover the desired area and as the wells rise or drop the outputs need to be throttled to keep the spraying constant and uniform. They need a bigger pump to draw from deeper wells but at other times of the season the wells have higher water. Hence the need to throttle the bigger pumps back. It also saves serious amounts of electricity on things like 300HP pumps.
It's my understanding that the pumps do last longer but not greatly so. Not enough for there to be any kind of an economic aspect. You're absolutely correct that positive displacement pumps would definitely see more load with restrictions. Thankfully I don't think there are any in aquariums with the exception of peristaltic metering pumps.
In industry many, many pumps are throttled in the normal course of things. Often they are throttled to control downstream pressure. Agriculture throttles a ton because those large field irrigators often need a specific pressure to cover the desired area and as the wells rise or drop the outputs need to be throttled to keep the spraying constant and uniform. They need a bigger pump to draw from deeper wells but at other times of the season the wells have higher water. Hence the need to throttle the bigger pumps back. It also saves serious amounts of electricity on things like 300HP pumps.
Wow, you learn something new everyday, and today this was it!...Thanks, ill stand corrected! Now i feel alot better about having to put those 90's in my closed loop system...it might flow less, but at least i have piece of mind that im not tearing that new reeflow pump up...
Yeah, I'm helping with a project at work where we need to buy/design the most efficient centrifugal pumps possible to pump Titanium Dioxide/Water slurries from treatment tanks to other parts of our plant. However, these slurries vary in treatments; viscosity, SG, and other things are varied. I'm now researching variable-vane/geometry pumps.
So, believe it or not, this post might have just helped a ton!
I'll have to do some testing to see if the same power-drop results will happen using liquid-suspended solids.
Oh I see, you're talking about the U-tubes in a HOB overflow box? Add a second U-tube or replace the existing one with a larger diameter. You can make one fairly easily out of some hose and barb fittings, or PVC, or if you wander the toilet repair section at home depot there is some stuff there that I have used before as well.
