1. ## plumbing, head, gravity flow, system curve, etc..

an attempt to place varying diagrams and explanations into one thread. 2. difference between gravity flow of water and pressurized flow of water.

GRAVITY FLOW OF WATER
• when water flows between 2 bodes of water. that are connected by a common channel / stream / pipe. and simply the difference between the heights of water level between the 2 bodes of water, causes the water to move from one body of water to the other body of water. this would be known as gravity flowing of water
• Or in another thought to above comment "water seeks its own water level".
• another way to identify gravity flow. is when ever water flows from one body of water to another body of water. and both bodies of water are open to the air. aka not sealed tighted containers.
• water in a stream does NOT flow UP HILL, but it flows down hill. hence gravity flow of water.
• when water falls off a waterfall weir. the water doesn't go up towards the sun. the water falls down. hence water falling down, or rather gravity flow of water.
• when you have a sink full of water and you pull the drain. the water flows out the drain by gravity.

PRESSURIZED FLOW OF WATER
• when ever water is flowing up hill. the water is in a pipe or encased in a filter, that is not open to the atmostphere. normally a water pump or perhaps an air lift pump or some other device provides HEAD (( pressure )). to move the water up the hill
• the pipe, fittings, and filters, between water pump inlet side (( suction side )) to the first body of water that is open to the atmosphere.
• the pipe, fittings, and filters, between water pump outlet side (( pressurse side )) to the first body of water that is open to the atmosphere.
PICTURES / DIAGRAMS
the animated diagram is simply showing a pond and 3 gravity flow filters. it would act something like #2, #3, #9, #11 in diagrams below the animated diagram.
1. water pump is off
2. water pump gets turn on
3. water pump starts draw water from filter 3
4. fitler 3 water level lowers.
5. water gravity flows from filter 2 into filter 3
6. filter 2 water level lowers
7. water gravity flows from filter 1 into filter 2
8. filter 1 water level lowers
9. water gravity flows from pond into filter 1
10. water gravity flows into pond, from waterfall
11. as water fills up pond, pond water level rises a little bit.
12. eventally, all water levels will find a running water level.

the misc diagrams 1 through 12, are a bad attempt by me to show pressuized flow of water in a pipe or filter, and gravity flow of water in pipes and filters. 3. animated diagrams show gravity flow of water, with debrie flowing pond and a couple filters.

FIRST ANIMATED PICTURE BELOW
( top or left hand side diagram )
1. water pump is off
2. water pump gets turn on
3. water pump starts draw water from filter 3
4. fitler 3 water level lowers.
5. water gravity flows from filter 2 into filter 3
6. filter 2 water level lowers
7. water gravity flows from filter 1 into filter 2
8. filter 1 water level lowers
9. water gravity flows from pond into filter 1
10. water gravity flows into pond, from waterfall
11. as water fills up pond, pond water level rises a little bit.
12. eventally, all water levels will find a running water level.
13. at this time i toss a peice of debriee (( brown chunk in diagram )) into pond, and show the debrie slowly moving through pond and filters. and slowly getting broken down and removed from the water.

SECOND ANIMATED PICTURE BELOW
( bottom or right hand side diagram )
this is my bad attempt to show water flow through pond and the 3 gravity flow fitlers. by using the brown color as flow direction. 4. differrent types of head losses, and/or friction losses.

• head is a form of measurement of pressure. example PSI (( pressure per square inch )). Head is a measurment of depth of water. normally measured in, feet, inches, meters, or centi-meters.
• for other forms of pressure and ways to convert pressure from one pressure to another pressure check out below site. once at site. scroll down and click on pressure.
• http://www.onlineconversion.com
FRICTION LOSS
• friction is friction. have you ever gotten a rug burn? if ya did, your skin and the rug caused friction. the result was you getting burned.
• when folks refer to friction loss. they are normally refering to water flowing through a... ( pipe, fitting, fliter, filter media, or other ) were due to friction. there is a loss of head ( pressure ) of the flow of water.
• friction loss, could be known as back pressure by some folks.
• friction loss, could be known as head loss by some folks.
• pretty easy and straight forward head measurement.
• the vertical ( up down ) distance between pond surface water level. and the highest point water exits above the pond surface water level.
• NOTE. this does not include pipeing, fittings, filters, etc... this is only the vertical measurent. not lengths or amounts of anything. just the vertical measurement.
• not everyone will have static head loss. example if you don't have a waterfall you may not have any static head.
• normally measured in feet of head.
• dynamic meaning it changes, never constant.
• there are 2 types of dynamic head.
• Major
• deals with length of straight pipe. in a pipe run.
• Minor
• deals with fittings, valves in a pipe run.
• some things to keep in mind, when dealing with dynamic head loss.
• the fast the flow rate, the more head loss you will have.
• a smaller sized diamter pipe vs a larger sized diamter pipe. the smaller pipe will have more dynamic major head loss vs the larger pipe that will have less dynamic major head loss.
• a smaller sized diamter fittings vs a larger sized diamter fittings. the smaller pipe will have more dynamic major head loss vs the larger pipe that will have less dynamic major head loss.
• longer the length of straight pipe you have. the more head loss you will have.

• Dynamic MAJOR head deals with straight length of pipe.
• there are many varities to caculate the head loss. 3 of the more common ways to caculated dynamic major head loss are...
1. darcy weisbach head loss equation
• this seems to be the more favored equation out there, for caculating dynamic major head loss. namely, the equation can work with alot of other liquids, such as salt water and gas (air) in calculating the dynamic major head loss.
• the equation itself is best used in a spread sheet or some program. were a computer can perform the multi calulations in only a matter of a second. compared to hand writing it out could take a good sum of time.
• the equation relies on 2 other numbers that can be derived from a set of other eqations. one of which is reynolds number. this number will determind what the other equation gets used for the 2nd number.
• this 2nd number is the friction factor. pending on what renoylds number equals, there could be a easy list of 10 plus equations you could then use to obtain the best closet caculated estimated dynamic major head loss.
• if ya more intrested in what is what. do a search on your favorite search engine. for "head loss" or "darcy weisbach head loss" or "cole-broke equation" or "moody diagram" or swain jain friction factor, or... and the list goes on.
• a good source of information can be found at...
2. hazen and williams head loss equation
• this equation is only good for fresh water, attempt to use it for salt water or gas ( air ) and you be out of luck. this equation is handy for out in the field and you want to quick way to calculate the dynamic head loss, without going through a bunch of math. the numbers that are returned from the equation are more off than what darcy weisbach equation would be.
3. mannings equation.
• this equation is more favored for gravity flow of water. such as streams and channels.

• all 3 give almost the same dynamic head loss. but there can be enough of a difference to have another 2 or 4 feet more loss than another equation.
• dynamic minor head loss is for calculateing the loss of fittings and valves.
• there are a couple sets of equations.
• one equation will give you the equvilent straight length of pipe.
• while another will give you a dynamic minor head loss.
• both of the equations rely on a K value, or rather K coefficent for the fitting or valve. some times instead of a K coefficent, there will be a CV coeffiecent in which there is an equation to convert a CV coefficent to a K coefficent. ya getting lost yet? i know i have multipule times!
• this is only going to be getting used for gravity flow filters.
• what below equations will tell us. is that a given inside diameter of pipe. with a given flow rate. will require this much difference in elevation difference between 2 bodies of water, surface water level (( say that 10 times fast ))
• . the below equation does not take into account dynamic head loss, or filter head loss.
• there 2 reasons for obtaining suction head.
• the first is to include the head loss when figuring total head.
• the 2nd reason of suction head. is to calculate the cavitation point of a water pump.
• in lamen terms. the cavtation point of a water pump. is the point were the pump creates so much suction. that the water pump litterly pulls the air out of the water.
• normally water pumps can push (outlet side) a great deal more pressure. vs pulling pressure. (inlet side) and this is due to cavitation. and reason why you rarly ever see a pressurized filter on the inlet side of a water pump. or less the given person knows there stuff more or less.
• another reason why you see water pumps with a bigger inlet vs outlet. is due to larger diameter pipes and fittings create less dynamic head loss. vs smaller sized diameter pipes and fittings.
• gravity flow filters can have draw down issues. meaning.
• folks improperly selected a water pump. and the water pump is litterly to big / sucking the gravity filter nearest to the pump inlet. competely dry of water.
• or they improperly sized the diameter of there pipes and fittings. for there gravity flows, and are having problems with water level needing to be 2 low. to flow the given flow rate they want to flow. through there filter setups.
• draw down head losses = the sum of...
• ya can't have a total head without a filter head losses.
• most of the time manufactors will state a range of flow rates for a filter. most likely ya prolly want to stay within those flow rates for any given filter. and ya prolly be wanting to stay within those flow rates. there be limits for a reason some were in there.
• but the more tricker part than finding flow rates. are the friction losses, or the head losses at given flow rates. for the filter or device.
• you will most likely find the losses for pressurized filters, more so for bead filters and sand filters (( think of a type pool type pressurized filter ))
• on gravity flow filters, it may be slim pickings, mainly due to gravity flow filters if they have any sort of head loss, it will have a dramatic effect on draw down head. and if there has to be 12 inches of draw down head to flow water. ya talking about 12 inches of a filter chamber that is not getting used. filter chambers are costly always have and prolly always will be.

• total head or rather total head loss. is a sum of the follwoing...
• sum of each pressuized flow of water head losses
• sum of draw downs
• sum of pressurized filter losses
• sum of any additional losses incured in the setup.
• total head is mostly used to create a profile system curve chart for there setup. with a system curve. folks can then find out what pump would best fit there setup.
• because folks ((including myself)) end up changing something here or there during the planning stages and building stages, and selecting different things. if folks buy a water pump right off the get go. they could easly have bought a pump that does not produce enough flow or to much flow for there setup. and because of this we have, heads, and system curves. 5. diagrams showing different heads with explanations

(( will fill in data later upon diagrams )) 6. dyname major head loss charts were calculated using.
• darcy weisbach head loss equation in feet = ( FF * ( LEN / DIA ) * ( ( VEL^2 ) / (2 * 32.174 ) ) )
• FF = swain jain friction factor equation = 0.25/(LOG(( COE / DIA /3.7)+ (5.74/ REN^0.9))^2)
• REN = reynolds number" = VEL * DIA / KEN
• KEN = kinematic viscosity in feet squard per second = 0.0000121
• COE = darcy weisbach roughness coefficent = 0.000005
• LEN = length of straight pipe in feet = 10 feet
• DIA = inside pipe diameter in feet
• VEL = velocity in feet per second 7. dynamic minor head loss charts

currently no charts

until then. check out...
scroll about half way down the page. and they give information of how to calculate fittings and valves. 8. ELEVATION DIFFERENCE head loss was calulated with...
• ELE = ( ( CFS * CFS ) / ( AF * AF ) ) ) / ( 2 * G)
• ELE = elevation difference head in feet.
• GPH = gallons per hour
• CFS = cubic feet per second = GPH / ( 7.48 * 60 * 60 )
• AF = area of a circle in feet = ( diameter in inches * diameter in inches * PIE ) / 576
• PIE = 3.14
• G = 32.174 in feet per second squared = acceleration of gravity 9. 1st example of calculating total head loss

who has known lengths of pipes and amount of fittings and inside diameter of all of them.

something easy 10. 2nd example of calculating total head loss

something abit difficult, couple bottom drains, a few sets of filters, a couple waters pumps, etc... who has there info of...

length of straight pipe and there inside pipe diameter
amount of fittings and there inside pipe diameter 11. creating a system curve

will edit fill in data later. 12. another system curve example

will fill in data later 13. sizing pipes and fittings (( aka estimating before ya start building and install your filters and plumbing. ))

will fill in later.
a remind for myself.

general rule of thumb flow rates, for gravity flow pipe runs.
(( note to myself make a big deal of general rules in that they can be a bad doing))

3600 gallons per hour for 4" pipe with a 1 inch draw down head
2000 gallons per hour for 3" pipe with a 1 inch draw down head
700 gallons per hour for a 2" pipe with a 1 inch draw down head

will fill in more data later with some charts and basic examples. including pressurized flows of water. 14. nothing but equations / formulas / and lots and lots of math

general post, to hold varying equations.

• area formulas.
• square = length * length
• rectangle = length * width
• circle = diameter * diameter * pie / 4
• parralllelogram = base * height
• trapezoid = height / 2 * ( base A + base B )
• right triangle = width * height / 2
• volumn formulas
• pyramid = area of base * height * ( 1 / 3 )
• cone = radius * radius * pie * ( 1 / 3 )
• half of a sphere = radius * radius * radius * pie * ( 4 / 3 ) / 2
• cube = length * width * height
• prisim = area of triangle * height
• bottom drain gap height
• to set gap height for dome
• gap height = radius of pipe connected to drain* radius of pipe connected to drain / diameter of dome
• above formula works for most manufactor drains, diy drains or domes on the other hand may be different story.
• ELEVATION DIFFERENCE head loss in feet
• ELE = ( ( CFS * CFS ) / ( AF * AF ) ) ) / ( 2 * G)
• ELE = elevation difference head in feet.
• GPH = gallons per hour
• CFS = cubic feet per second = GPH / ( 7.48 * 60 * 60 )
• AF = area of a circle in feet = ( diameter in inches * diameter in inches * PIE ) / 576
• PIE = 3.14
• G = 32.174 in feet per second squared = acceleration of gravity #### Posting Permissions

• You may not post new threads
• You may not post replies
• You may not post attachments
• You may not edit your posts
•