head loss
- Thread starter speedstar
- Start date
heyfredyourhat
Premium Member
yes
wooden_reefer
New member
"head loss" vs head loss
Head loss is to overcome gravity, but friction is summarized as if it is due to gravity, even though it is due to friction.
In stead of saying head loss plus friction loss we say "head loss" for all. Friction increases with velocity, flow, real head loss does not.
Head loss is to overcome gravity, but friction is summarized as if it is due to gravity, even though it is due to friction.
In stead of saying head loss plus friction loss we say "head loss" for all. Friction increases with velocity, flow, real head loss does not.
dots
Premium Member
I have always hated this term due to its ambiquity.
1. Pressure/Specific weight of the fluid is called "pressure head"
2. Gravity creates the "elevation head" with change in height.
3. The velocity of the fluid squared/2 times gravity is th velocity head.
The sum of these three equations is what is called the "Total Head", which is used to create Bernoulli's Equation.
The two main ones we deal with in somewhat more specific jargon:
1. Minor losses due to friction, ie: effected by pipes bends and fittings
1. Losses/Gains due to gravity: Self explanatory.......
In most tanks, the inlet and outlet of the CL is at the same level and not very deep under water, so the pressure is minimal and can be counted as zero. Using the Energy Equation,
found here as well as all the concepts in a very well written article for those not famillar with fluid mechanics:
http://www.advancedaquarist.com/issues/jan2003/featurejp.htm
(I find the minor losses for PVC information located here gold!!),
-z1+(+z2) equal zero or no head loss (or gain) due to gravity if the entrance and exit is at the same height. (If there was, the water would flow through the pipe without the aid of a pump)
However, there will be loss due to friction based on the pipe size, length and fittings which as has an effect on exit velocity and efficency of the CL.
I know, I know a little wordy and in line with the above......but hey.....its the Advanced Topics forum........I think the answers should be a little more technical........stays off the Alzhiemers........now what was I doing?
located in that article is an Excel file, play with your design and optimize your flow. Better yet, for some real fun.....do it by hand.
1. Pressure/Specific weight of the fluid is called "pressure head"
2. Gravity creates the "elevation head" with change in height.
3. The velocity of the fluid squared/2 times gravity is th velocity head.
The sum of these three equations is what is called the "Total Head", which is used to create Bernoulli's Equation.
The two main ones we deal with in somewhat more specific jargon:
1. Minor losses due to friction, ie: effected by pipes bends and fittings
1. Losses/Gains due to gravity: Self explanatory.......
In most tanks, the inlet and outlet of the CL is at the same level and not very deep under water, so the pressure is minimal and can be counted as zero. Using the Energy Equation,
found here as well as all the concepts in a very well written article for those not famillar with fluid mechanics:
http://www.advancedaquarist.com/issues/jan2003/featurejp.htm
(I find the minor losses for PVC information located here gold!!),
-z1+(+z2) equal zero or no head loss (or gain) due to gravity if the entrance and exit is at the same height. (If there was, the water would flow through the pipe without the aid of a pump)
However, there will be loss due to friction based on the pipe size, length and fittings which as has an effect on exit velocity and efficency of the CL.
I know, I know a little wordy and in line with the above......but hey.....its the Advanced Topics forum........I think the answers should be a little more technical........stays off the Alzhiemers........now what was I doing?
located in that article is an Excel file, play with your design and optimize your flow. Better yet, for some real fun.....do it by hand.
Last edited:
I studied a these things in aquarium sysem design. Basically we used to calculate TDH( total dynamic head) Frictional losses due to fittings and pipe diameter and length. The calculations require alot of steps. If you need to know the TDH of your system this site can calculate it for you.
RichConley
New member
Precula, for a closed loop, using that calculator the person essentially has to put "0" for the vertical height, and ALL of the pipe as "horizontal"
Essentially, head loss will approach zero as you go to larger pipe.
Essentially, head loss will approach zero as you go to larger pipe.
BeanAnimal
Premium Member
Okay.... gotta point something out
In most tanks, the inlet and outlet of the CL is at the same level and not very deep under water, so the pressure is minimal and can be counted as zero.
As long as they are in the same body of water, they ARE at the same "level" and therefore ARE counted as 0.
So a 200 mile tall tank with the intake at the bottom and the return at the top still has a 0 pressure and gravity head.
.... Just because we ARE being picky in the advanced forum
In most tanks, the inlet and outlet of the CL is at the same level and not very deep under water, so the pressure is minimal and can be counted as zero.
As long as they are in the same body of water, they ARE at the same "level" and therefore ARE counted as 0.
So a 200 mile tall tank with the intake at the bottom and the return at the top still has a 0 pressure and gravity head.
.... Just because we ARE being picky in the advanced forum
