Closed Loop Pump
- Thread starter Rudy
- Start date
OK now I am getting more confused?
all things being equal I should try to find a pump with the same inlet/outlet size as my PVC, right? So if a pump is different, like the velocity, I should avoid it?
I thought the purpose of a reducer was to accomdate such differences. i did not realize it was to the detriment of the flow?
all things being equal I should try to find a pump with the same inlet/outlet size as my PVC, right? So if a pump is different, like the velocity, I should avoid it?
I thought the purpose of a reducer was to accomdate such differences. i did not realize it was to the detriment of the flow?
Keith:
I have not responded concerning submersible pumps as I have no experience with them but I do know that with these pumps the heat is dissipated into the water and not into the atmosphere.
With respect to head losses the simplest way that I think about it is in terms of equivalent lengths of pipe. (I am assuming that you are aware of the concept of dynamic head loss or else you would not have questioned static head loss in a prior post.)
What many folks are not aware of is that reducers (or "expanders" if you want to use that word) have contraction as well as expansion head losses (ie. you might be "spinning your wheels" by installing a 3/4"x1" "expander" with a short length of 1" pipe).
There is nothing wrong with pumps which have different inflow and outflow sizes. The difference in the expansion head loss from the water flowing into the impeller chamber from a 3/4" inlet and a 1" is virtually negligible.
Please refer to the following for general equivalent lengths:
http://www.copperzone.com/english/tablee.htm
and to the following for detailed explanations:
http://www.cheresources.com/eqlength.shtml
http://utwired.engr.utexas.edu/che354/mom/pfit.ppt#10
TR
BTW: Some of my comments are relative to the home aquarium world but not relative to the public aquarium world due to the associated capacity of pumps and velocities.
With pumps you should normally not be changing pipe sizes anywhere near the pumps suction inlet. You are not even supposed to have any bends within 5 pipe diameters of the suction inlet as you will then have flow irregularities as the water enters the impeller.
That said people do it all the time and get by. They may be pumping less water than they otherwise could be or their pump is considered noisy because there is now cavitation that would otherwise not be present.
So I would not be changing pipe size at the pump unless I had to.
Thanks to Jones and Kcress for the opinions and expertise.
I am fortunate enough to have the space and resources to avoid most of the potential issues both of you outlined.
I will now try to find the quietest pump around with a 1" inlet/outlet.
Thanks again, Keith
I am fortunate enough to have the space and resources to avoid most of the potential issues both of you outlined.
I will now try to find the quietest pump around with a 1" inlet/outlet.
Thanks again, Keith
Given the gradual curves ceated with flexible piping, other than less stability is there any other ereason I should avoid using them? If I were to use flexible at all it would be solely for the clsoed loop whcih would make plumbing beneath the cabinet easier.
The sump line and return will be strictly solid PVC:grinyes:
The sump line and return will be strictly solid PVC:grinyes:
Keith:
No problem with flexible tubing in general. I have flexible tubing on the suction and discharge side of the pump.
Be careful to avoid a kink in the tubing (sounds simple but it can happen).
Keith:
I just thought of one other item. If you go with an external pump (which I recommend) please make the intake of the pump the lowest hydraulic element of the system.
Priming these creatures can be something else but if the suction line is flooded then no problem.
TR
No problem with flexible tubing in general. I have flexible tubing on the suction and discharge side of the pump.
Be careful to avoid a kink in the tubing (sounds simple but it can happen).
Keith:
I just thought of one other item. If you go with an external pump (which I recommend) please make the intake of the pump the lowest hydraulic element of the system.
Priming these creatures can be something else but if the suction line is flooded then no problem.
TR
The purpose of a closed loop system is to provide water movement. Why not invest in a pump that specializes only in water movement? Extra pressure shouldn't be necessary, nor is it desirable under such circumstances. The added velocity really isn't what you want--the ideal situation is a lot of high volume, low velocity (diffused) water movement.
