need help determining height for elevated tank
need help determining height for elevated tank
(OP)
i plan to install an above-ground, lube oil storage tank. the client wants this tank to be elevated high enough to tie into an existing oil header line without using a pump (i.e. gravity-fed).
The setup is: tank will be located outside; approximately 40 feet of 1" diameter piping will be used to connect to the existing oil line; tie-in to the existing 1" diameter oil line is ~2 feet above grade; Current oil consumption (flow rate) is a maximumn of 8 gallons per day; the oil used has a density is 7.3 lbs/gallon; assume coldest temp will be ~50-60°F;
I tried sizing the minimum elevation for gravity fed flow using bernoulli's equation and came up with an elevation which does not seem right to me - ~3 feet.
can someone direct me to steps in determining what the minimum tank height should be?
The setup is: tank will be located outside; approximately 40 feet of 1" diameter piping will be used to connect to the existing oil line; tie-in to the existing 1" diameter oil line is ~2 feet above grade; Current oil consumption (flow rate) is a maximumn of 8 gallons per day; the oil used has a density is 7.3 lbs/gallon; assume coldest temp will be ~50-60°F;
I tried sizing the minimum elevation for gravity fed flow using bernoulli's equation and came up with an elevation which does not seem right to me - ~3 feet.
can someone direct me to steps in determining what the minimum tank height should be?





RE: need help determining height for elevated tank
Elevation of main tank should be such that the day tank is not overpressurized (beyond tank rated working pressure). Also elevation should be such that pressure drop through piping including entry, exit, fittings & valves at the maximum gpm draw would be at least equal to the minimum elevation available when the lube oil is at its minimum level in the tank. You can use data from Cameron Hydraulic Data for water then apply density correction. Do trial & error solution and add safety factor.
Address how the lube oil tank will be filled.
Pipe lube oil supply and return to the lube oil day tank. Lube oil pump should be able to lift oil from the lube oil day tank.
RE: need help determining height for elevated tank
RE: need help determining height for elevated tank
what i really need help on is how to go about setting up the eqn to determine what the outlet elevation from the tank should be to reach the 8gpm flowrate.
currently they use a 55 gallon drum on an elevated stand to flow oil into this 1" header. i assumed energy equilibrium between this setup & the planned 2000 gallon tank setup. the eqn i used was:
?1÷? + v1÷2gc + z1 + hA = ?2÷? + v2÷2gc + z2 + hE + hf
assumed:
?1÷? = ?2÷? (because both tanks are @ atmospheric pressure)
hE = 0 because there is no pump involved
then determined hF =0.3 ft and solved for z2.
should i have made one side of the eqn = 0 and then solved for z2?
RE: need help determining height for elevated tank
p1÷rho + v1÷2gc + z1 + hA = p2÷rho + v2÷2gc + z2 + hE + hf
kahlilj
RE: need help determining height for elevated tank
Lilliput gave you good suggestions.
See the Thread378-116505
Regards,
RE: need help determining height for elevated tank
my other concern/question is which approach should i take to solve for z2:
1) equilibrium between existing drum tank & new 2000 gallon tank:
p1÷rho + (v1)^2÷2gc + z1 + hA = p2÷rho + (v2)^2÷2gc + z2 + hE + hf
OR
2) just calc total head of new tank alone:
H = p2÷rho + (v2)^2÷2gc + z2 + hE + hf
also thanks for the thread link. very helpful!
RE: need help determining height for elevated tank
So Z1 = P2/Ρ+v2[sp]2[/sup]/2gc+hf (I would like you explain hA and hE)
Regards,
RE: need help determining height for elevated tank
Noting the input of Quark, any swings in 2000 tank level will then impact system pressures.
RE: need help determining height for elevated tank
hf = frictional head = ~0.65 ft
hA = for hydraulic losses (turbine) = zero
hE = for hydraulic losses (pump) = zero
so if i go with existing header (2' above grade) as my datum then assume equilibrium at this point? if so, with the header line not being directly open to atmosphere, would pressure head still be zero? what would eqn look like if choosing existing header tie-in as my datum?
sailoday, level "control" needed is more or less just knowing the amount of oil remaining in the tank. so an indicator (without signal or control) is all that is needed.. level will be manually monitored.
RE: need help determining height for elevated tank
What Sailoday says is correct. Static head of oil changes as the level in the tank and it is better to design the system based on low level in the tank. But there may be overflow issues in day tank due to increased flowrate and that is why gravity flow of fuel oils from main storage tank to day tank is not allowed here in India.
Regards,