From http://www.geocities.com/gletiecq/theory3.htmlThe total head losses is a system are the sum of the hydraulic head losses, and the dynamic head losses, which include the "major" losses due to pipe friction, and the "minor losses" due to fittings, valves, and obstructions.
River tank manifold
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crazy loaches
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Graeme - I thinks its just the difference in terminology used... head loss usually refers to loss to due moving water up a certain height, given in units of feet, meters, etc. But Jones is just trying to account for all losses, even if some a relatively insignificant. Take a look at this description of head loss:
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Graeme McKellar
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Hi all, This thread has got way off track by talking about "head-loss" when there is virtually no head loss in Martin's design. It is a non-positive diplacement centrifical pump with flooded suction with NO outlet piping.
When talking of flow in piping it is "laminar" in straight piping which means the velocity in the centre of the pipe is greater than at the wall due to the "friction" of the water against the pipe wall.When an elbow is encountered the flow becomes "turbulent" and this reduces flow slightly but when it travels into straight pipe again the flow will become "laminar" again due to friction. Long-bends do reduce this "disturbance" in flow.
Maybe we can start another thead in Freshwater to discuss Hydraulics and Pumps and Filtration further. Cheers Graeme.
When talking of flow in piping it is "laminar" in straight piping which means the velocity in the centre of the pipe is greater than at the wall due to the "friction" of the water against the pipe wall.When an elbow is encountered the flow becomes "turbulent" and this reduces flow slightly but when it travels into straight pipe again the flow will become "laminar" again due to friction. Long-bends do reduce this "disturbance" in flow.
Maybe we can start another thead in Freshwater to discuss Hydraulics and Pumps and Filtration further. Cheers Graeme.
"I want to speak with many things and I will not leave this planet without knowing what I came to find, without solving this affair, and people are not enough. I have to go much farther and I have to go much closer." - Pablo Neruda.
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jones57742
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Folks
I have really "been hammered down through the years" for being "too technical".
Therefore I did not want to get "any deeper" into the basics but I believe that this in now appropriate due to a previous post.
The first portion comes from the Engineering World and the second portion comes from the Physics World.
In the Engineering World
Our aquariums are substantially closed systems.
Total head loss is the sum of Static Head (potential energy) and Dynamic Head (kinetic energy).
Dynamic head loss is the sum of suction head losses and discharge head losses.
Static head loss is not measured from the center of the pump.
Static head loss is measured from the lower water surface from which the pump is intaking flow to the higher water surface to which the pump is discharging flow.
Identical head losses are applicable to suction head losses as to discharge head losses (but typically the suction head losses are minimal.
I did "not get into it" in my previous post as suction head losses are typically minimal and occur at bulkheads, reducers/enlargers, in the tubing and in bends in the tubing, etc.
The moral of the story is that to properly utilize a pump curve the Static Head Loss, the Suction Dynamic Head Loss and the Discharge Dynamic Head Loss must be summed in order to yield the Total Head Loss.
In the Physics World
Hydraulics is very, very simple as it only consists of the conservation of energy concept.
Energy exists in two forms: potential and kinetic.
potential energy:
http://en.wikipedia.org/wiki/Potential_energy
"The more formal definition is that potential energy is the energy of position, that is, the energy an object is considered to have due to its position in space."
kinetic energy:
http://en.wikipedia.org/wiki/Kinetic_energy
The kinetic energy of an object is the extra energy which it possesses due to its motion.
This concept is expressed in a very simplistic form via the question
"what is the velocity of a non viscous substance with no specific gravity exiting one 1 meter of frictionless tubing placed in an infinitesimal hole in a "perfect" graduated cylinder in which 1 meter of water is present".
The solution is expressed as (and this is Torchell's Equation)
mgh = 1/2mv^2
where mgh is the potential energy in the graduated cylinder due to the head of the water surface and
1/2mv^2 is the kinetic energy of the water exiting the hole.
m=mass
g=gravitational acceleration
h=height of water in the cylinder (ie. head)
v=velocity
http://en.wikipedia.org/wiki/Conservation_of_energy
In physics, the conservation of energy states that the total amount of energy in any isolated system remains constant but can't be recreated, although it may change forms, e.g. friction turns kinetic energy into thermal energy
Unfortunately on the earth the above example is a very simplistic but incorrect approximation and hence Bernoulli's equation which accounts for "real world conditions".
I have really "been hammered down through the years" for being "too technical".
Therefore I did not want to get "any deeper" into the basics but I believe that this in now appropriate due to a previous post.
The first portion comes from the Engineering World and the second portion comes from the Physics World.
In the Engineering World
Our aquariums are substantially closed systems.
Total head loss is the sum of Static Head (potential energy) and Dynamic Head (kinetic energy).
Dynamic head loss is the sum of suction head losses and discharge head losses.
Static head loss is not measured from the center of the pump.
Static head loss is measured from the lower water surface from which the pump is intaking flow to the higher water surface to which the pump is discharging flow.
Identical head losses are applicable to suction head losses as to discharge head losses (but typically the suction head losses are minimal.
I did "not get into it" in my previous post as suction head losses are typically minimal and occur at bulkheads, reducers/enlargers, in the tubing and in bends in the tubing, etc.
The moral of the story is that to properly utilize a pump curve the Static Head Loss, the Suction Dynamic Head Loss and the Discharge Dynamic Head Loss must be summed in order to yield the Total Head Loss.
In the Physics World
Hydraulics is very, very simple as it only consists of the conservation of energy concept.
Energy exists in two forms: potential and kinetic.
potential energy:
http://en.wikipedia.org/wiki/Potential_energy
"The more formal definition is that potential energy is the energy of position, that is, the energy an object is considered to have due to its position in space."
kinetic energy:
http://en.wikipedia.org/wiki/Kinetic_energy
The kinetic energy of an object is the extra energy which it possesses due to its motion.
This concept is expressed in a very simplistic form via the question
"what is the velocity of a non viscous substance with no specific gravity exiting one 1 meter of frictionless tubing placed in an infinitesimal hole in a "perfect" graduated cylinder in which 1 meter of water is present".
The solution is expressed as (and this is Torchell's Equation)
mgh = 1/2mv^2
where mgh is the potential energy in the graduated cylinder due to the head of the water surface and
1/2mv^2 is the kinetic energy of the water exiting the hole.
m=mass
g=gravitational acceleration
h=height of water in the cylinder (ie. head)
v=velocity
http://en.wikipedia.org/wiki/Conservation_of_energy
In physics, the conservation of energy states that the total amount of energy in any isolated system remains constant but can't be recreated, although it may change forms, e.g. friction turns kinetic energy into thermal energy
Unfortunately on the earth the above example is a very simplistic but incorrect approximation and hence Bernoulli's equation which accounts for "real world conditions".
Hookem Horns and Keep Austin Weird
In the short run the good guys never win:
In the long run they win some of the times!
In the short run the good guys never win:
In the long run they win some of the times!
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