|
Posted by RJAG on June 7, 2005, 6:27 am
Please log in for more thread options
I take it then that its not a good idea to have a largish pump and run it
flat out, for I was planning such a thing on my 42 Gallon tank.
Robin
|
|
Posted by CheezWiz on June 7, 2005, 6:05 pm
Please log in for more thread options
You also have to add in additional head length for elbows, bends and T's....
Each elbow adds enough flow resistance to equal a significant amount of head
length.
I would have to do a search to find some specifics....
(Anyone here WELL versed in fluid dynamics?)
Unless a person is really worried about energy consumption or heat, then
just buy one plenty big and use a valve AFTER the pump to control flow
rate...
> BigMike wrote:
>> Where do you measure from to get the distance for the head above a sump
>> pump? Do you measure from the pump in the sump to the water level in show
>> tank or do you measure from the top water level in the sump to the water
>> level in the show tank? I'm trying to figure out which pump I need, or
>> is
>> it better to just get an over sized pump and use a ball valve to get the
>> flow to the right rate. Thanks.
>>
>>
> You measure from the water level in the sump to the water level in the
> tank. Of course then you have to add in the frictional head loss also.
>
> I would always suggest going oversized and use a valve to controll the
> flow since you never know when you might want to add something new to your
> tank, like a CA reactor feed off of your return pump, or a fuge or surge
> device etc.
>
> Kim
|
|
Posted by kim gross on June 8, 2005, 12:01 am
Please log in for more thread options
CheezWiz wrote:
> You also have to add in additional head length for elbows, bends and T's....
> Each elbow adds enough flow resistance to equal a significant amount of head
> length.
> I would have to do a search to find some specifics....
>
> (Anyone here WELL versed in fluid dynamics?)
>
> Unless a person is really worried about energy consumption or heat, then
> just buy one plenty big and use a valve AFTER the pump to control flow
> rate...
>
>
The amount of frictional losses are determined by the velocity of the
water in the pipe, so if you increase the size of the pipe even with
lots of elbows bends T's etc, there will be very little flow loss. This
is why I always say go at least one pipe size larger, and even better 2
pipe sizes larger. You can use the head loss calculater on reefcentral
to give you an idea of the head losses you will have. It is not perfect
since the type of pipe you use (ie schedule 40/80 or the thin wall) will
effect the flow rate quite a bit plus different manufactures have
different coeffectiants of friction, but it is a very good aproximation.
Kim
|
|
Posted by Frank on June 13, 2005, 10:06 pm
Please log in for more thread options
Question, instead of 90 degree elbows what about long-radius elbows. That
should reduce head pressure, Right?
Frank
> CheezWiz wrote:
> > You also have to add in additional head length for elbows, bends and
T's....
> > Each elbow adds enough flow resistance to equal a significant amount of
head
> > length.
> > I would have to do a search to find some specifics....
> >
> > (Anyone here WELL versed in fluid dynamics?)
> >
> > Unless a person is really worried about energy consumption or heat, then
> > just buy one plenty big and use a valve AFTER the pump to control flow
> > rate...
> >
> >
>
>
> The amount of frictional losses are determined by the velocity of the
> water in the pipe, so if you increase the size of the pipe even with
> lots of elbows bends T's etc, there will be very little flow loss. This
> is why I always say go at least one pipe size larger, and even better 2
> pipe sizes larger. You can use the head loss calculater on reefcentral
> to give you an idea of the head losses you will have. It is not perfect
> since the type of pipe you use (ie schedule 40/80 or the thin wall) will
> effect the flow rate quite a bit plus different manufactures have
> different coeffectiants of friction, but it is a very good aproximation.
>
> Kim
|
|
Posted by kim gross on June 14, 2005, 12:56 am
Please log in for more thread options
Yes a long radius elbow will reduce the head pressure over a normal
elbow, but what will reduce it the most is going to a large diameter
pipe. If you increase your pipe from from 1 to 2 sizes larger than you
think you need, the friction of elbows and other fittings is pretty
close to zero so you do not need to worry about any fittings to put on
the pipe even if you have the pipe doing figure 8s. Since with the
larger diameter the velocity is lower, it is easier for the water to
change directions.
Kim
Frank wrote:
> Question, instead of 90 degree elbows what about long-radius elbows. That
> should reduce head pressure, Right?
>
> Frank
>
>
|
| Similar Threads | Posted | | Plumbing question - RO delivery pump pulses | May 19, 2005, 11:46 pm |
| Sump/refugium question. | May 28, 2005, 4:28 pm |
| Noisey Red Sea Pump | July 9, 2005, 9:24 am |
| 12v pump - power head | March 14, 2005, 8:53 pm |
| Pump Life Expectancy | March 29, 2005, 7:41 pm |
| Pressure pump recommendations? | April 5, 2005, 12:43 am |
| Peltier pump cooler.... | June 1, 2005, 9:04 am |
| dosing pump with ESV B-Ionic 2 part | June 4, 2009, 7:45 pm |
| Any impressions on the new Ecotech Marine Vortech Pump | June 12, 2006, 10:33 pm |
| Sump | March 10, 2005, 10:12 pm |
|
|
Yahoo! 
Google 
Windows Live 
del.icio.us 
digg 
Netscape 
XML Sitemap