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ReefBones 
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 Topic: Flow restrictions
Posted: February 13 2007 at 11:49pm |
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Ok .. I heard somewhere a while ago that a 90 degree elbow on your return line can take away up to 10% of your water pressure is this true? ... so is it true that if I have a Mag 2400 .. that has a total of 4 90 degree elbows that is taking away 40% of the water flow back to my tank? ...
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140 gallon Reef
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www.thesalttank.com
801-865-6074
"encourage other divers and sea enthusiasts to take nothing but pictures and leave nothing but bubbles"
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jfinch
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Posted: February 14 2007 at 9:15am |
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It's actually a little complicated (it depends on the pump discharge curve, flow rate and pipe size), but ~10% for that size pump and plumbing is certainly in the right ballpark.
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Mike Savage
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Posted: February 14 2007 at 9:35am |
 thebutler4 wrote:
Ok .. I heard somewhere a while ago that a 90 degree elbow on your return line can take away up to 10% of your water pressure is this true? ... so is it true that if I have a Mag 2400 .. that has a total of 4 90 degree elbows that is taking away 40% of the water flow back to my tank? ... |
A 90 degree elbow takes away 10% of your water PRESSURE?
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jfinch
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Posted: February 14 2007 at 10:00am |
No, flow.
Actually, as you add elbows to piping system, you'll see the pump discharge pressure increase (which means the flow is decreasing).
But it's not the same percentage for each added elbow. As the flow decreased, the flow restricting effect of another elbow is diminished.
I should make up a spreadsheet for pumped piping systems...
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Mike Savage
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Posted: February 14 2007 at 10:28am |
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Ok, not too much off topic. How is pump head distance measured? From the top surface of the sump to the top surface of the tank?
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jfinch
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Posted: February 14 2007 at 10:37am |
How is pump head distance measured? From the top surface of the sump to the top surface of the tank?
Yes, surface level to surface level will give flow loss due to elevation change.
The other big factor is frictional losses. This is where pipe diameter, number/type of fittings and flow rate comes into play.
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Mike Savage
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Posted: February 14 2007 at 12:01pm |
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Excellent. Thanks.
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Gahlenfr
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Posted: February 14 2007 at 3:40pm |
Jon, help me understand this in laymans terms. If I start out at 10 gpm what flow do I have at the end assuming this data?
Example of Friction Head Loss in Plastic Pipes
A flow of 10 GPM in a 2" pipe gives a head loss of 0.2 feet water column per 100 feet of pipe
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jfinch
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Posted: February 14 2007 at 3:50pm |
Jon, help me understand this in laymans terms. If I start out at 10 gpm what flow do I have at the end assuming this data?
A flow of 10 GPM in a 2" pipe gives a head loss of 0.2 feet water column per 100 feet of pipe
Well... you still have 10 gpm, since that is what you assumed to start with. What that statement means is that water flowing at 10 gpm through a 2" pipe will lose 0.2 ft of pressure after traveling 100 ft.
This would be much easier to explain/show if we were sitting around a table. It's easy to show graphically how your system curve (piping characteristics) interacts with the pump curve. Let me mark up a pump curve, post it and try to explain it from that...
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jfinch
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Posted: February 14 2007 at 5:03pm |
Here's a couple charts I've posted before for figuring frictional pressure losses.
And
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ReefBones
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Posted: February 15 2007 at 1:39am |
WOW jon .. that was a lot more than I expected! thank you much but I am a total idiot when it comes to this stuff .. lol ... so .. to simplify my question .. on my mag24 ... with just 1 "T" (barbed fitting) going threw 3/4" tubing ... and pushing 8' how much do you think I am really pushing ... pump says 2400 GPH at 0 feet ... and 1400gph at 9 feet (according to the tell tell manufacture specs) .... how much flow am I loosing with just the 1 barbed "T" fitting running threw 3/4" tubing ?
Edited by thebutler4 - February 15 2007 at 1:40am
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140 gallon Reef
65 gallon Reef
55 gallon Aggressive
www.thesalttank.com
801-865-6074
"encourage other divers and sea enthusiasts to take nothing but pictures and leave nothing but bubbles"
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Corey Price
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Posted: February 15 2007 at 8:42am |
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There's a calculator on Reefcentral. It used to be an excel spreadsheet, but it's now just a calculator. I still have the excel spreadsheet. It accounts for bernouli's eq, Hazen-williams, losses due to elbows, tees, etc. It even has pump curves built in.
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jfinch
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Posted: February 15 2007 at 9:22am |
to simplify my question...
Probably around 1100 - 1200 gph.
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Mike Savage
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Posted: February 15 2007 at 9:55am |
Cool stuff. Thanks for the chart.
Mike
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ReefBones
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Posted: February 15 2007 at 12:15pm |
Man .. I need to find a MAg36!!!!! .. lol
I worry that may not be enough for SPS ...
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140 gallon Reef
65 gallon Reef
55 gallon Aggressive
www.thesalttank.com
801-865-6074
"encourage other divers and sea enthusiasts to take nothing but pictures and leave nothing but bubbles"
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ReefBones
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Posted: February 15 2007 at 2:59pm |
ok I just removed the last 2 90* elbows on my return lines ... and I would be willing to bet that doubled + the flow back into the tank .. even the return pump sounds better .. (not as loud) ... so .. that should help ..
Please see my second question about SPS in the corals forum ..
Thanks again guys!!! .. I love this board!
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140 gallon Reef
65 gallon Reef
55 gallon Aggressive
www.thesalttank.com
801-865-6074
"encourage other divers and sea enthusiasts to take nothing but pictures and leave nothing but bubbles"
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jfinch
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Posted: February 15 2007 at 4:05pm |
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You'll see even better results if you switch to 1" tubing rather then the 3/4".
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