Does head pressure measure only upward flow?
- Thread starter t11t5
- Start date
jdieck
New member
No, I'll try to explain.
Head discharge pressure is basically set by two ccomponents, the static head pressure which is basically the one you describe. It is basically the pressure exerted by the vertical column of salt water measured from the surface of the water in the sump to the surface of the water in the main tank.
The second component is the dinamic head pressure. This is the backpressure created by the piping sistem oposing to the flow of water in movement.
The dinamic head increases with:
a) The higher the flow (Water velocity) the higher the head pressure.
b) The smaller the pipe diameter the higher the head pressure.
c) the viscosity of the fluid, the higher it is the higher the head pressure
d) The roughtness of the inside surface of the pipe, the roughter it is the higher the pressure loss
e) Changes of direction. The more changes of direction the higher the head pressure
f) The sharpness or radius of the change of direction. The sharper the turn the higher the head pressure
g) The total lenght of the pipe regardless if vertical or horizontal. The longer the higher the head pressure.
h) Any change in diameter or couplings and the quality of the couplings along the pipe.
This dinamic pressure is the part most difficult to calulate but to simplify things lets say thet the most significant factors are the pipe diameter and the number of elbows. Use large radius elbows or 45* elbows to reduce pressure drop. An increase of 50% in pipe diameter reduces the dinamic head pressure by 225%.
A 1" pipe has only 56% the drop of a 3/4" pipe and a 1.5" pipe has only 44% of the pressure drop of a 1" pipe regardless of the size of the conectors in the pump. As an Example, Mag Drive Pumps from 9.5 to 18 have 3/4" connections but the manufacturer pressure drop charts are rated using 11/2" pipe diameter with the pumps.
The Iwaki 70 RLT and 100 RLT have 1" conections but they shall be also used with 11/2" pipe in the discharge and 2" pipe in the inlet for maximum performance.
Hope this info help you better design your system.
Head discharge pressure is basically set by two ccomponents, the static head pressure which is basically the one you describe. It is basically the pressure exerted by the vertical column of salt water measured from the surface of the water in the sump to the surface of the water in the main tank.
The second component is the dinamic head pressure. This is the backpressure created by the piping sistem oposing to the flow of water in movement.
The dinamic head increases with:
a) The higher the flow (Water velocity) the higher the head pressure.
b) The smaller the pipe diameter the higher the head pressure.
c) the viscosity of the fluid, the higher it is the higher the head pressure
d) The roughtness of the inside surface of the pipe, the roughter it is the higher the pressure loss
e) Changes of direction. The more changes of direction the higher the head pressure
f) The sharpness or radius of the change of direction. The sharper the turn the higher the head pressure
g) The total lenght of the pipe regardless if vertical or horizontal. The longer the higher the head pressure.
h) Any change in diameter or couplings and the quality of the couplings along the pipe.
This dinamic pressure is the part most difficult to calulate but to simplify things lets say thet the most significant factors are the pipe diameter and the number of elbows. Use large radius elbows or 45* elbows to reduce pressure drop. An increase of 50% in pipe diameter reduces the dinamic head pressure by 225%.
A 1" pipe has only 56% the drop of a 3/4" pipe and a 1.5" pipe has only 44% of the pressure drop of a 1" pipe regardless of the size of the conectors in the pump. As an Example, Mag Drive Pumps from 9.5 to 18 have 3/4" connections but the manufacturer pressure drop charts are rated using 11/2" pipe diameter with the pumps.
The Iwaki 70 RLT and 100 RLT have 1" conections but they shall be also used with 11/2" pipe in the discharge and 2" pipe in the inlet for maximum performance.
Hope this info help you better design your system.
Holmez221b
New member
This helps alot.... I have a Genx mak 4 I'm going to plumb in, it has a 3/4 outlet, if I'm reading the thread correctly I shoud plumb the outlet in 1" to reduce head pressure
jdieck
New member
A Genx Mak4 with 3/4" pipe assuming 6 ft vertical, 2 ft horizontal, 4 90* elbows, one union coupling and one ball valve will heave a head pressure of 12.7 feet and a flow of 793 gph.
The same installation with 1" dia pipe will have a head of 9 feet and provide 932 gal/hr.
Now you also need to insure that your overflow can handle the amount of water the pump will put in the main tank.
This Calculator might help with estimating the flow:
http://reefcentral.com/calc/hlc2.php
This calculator can help with estimating the overflow drain:
http://reefcentral.com/calc/drain.php
The same installation with 1" dia pipe will have a head of 9 feet and provide 932 gal/hr.
Now you also need to insure that your overflow can handle the amount of water the pump will put in the main tank.
This Calculator might help with estimating the flow:
http://reefcentral.com/calc/hlc2.php
This calculator can help with estimating the overflow drain:
http://reefcentral.com/calc/drain.php
Holmez221b
New member
The calculator only lets you choose the dia of the pipe to the inlet of the pump...not the outlet, unless it assumes the inlet and outlet will be the same, but I doubt it. Also if the pump is made with 3/4 inlets and outlets will the head pressure be helped by using 1" pipe to "fool" the pump...
jdieck
New member
No it is the other way around, it works for the pump outlet not the inlet and it lets you select any pipe diameter you need and assumes that the dia of the piping selected is the same after the pump discharge to the end of the pipe length.
The discharge or inlet diameter of the pump is designed to provide the pump discharge characteristics and it is not intended to define the diameter of the pipe that needs to be used. The dynamic head pressure is created by the piping you install regardless of the diameter of the pump connections.
As I mentioned above manufacturers like Daner (Mag Drives) recommend using 11/2" dia pipe while their pumps have outlets of 3/4" dia.
In other words the diameter of the pipe has nothing to do with the diameter of the pump connections other than to determine the right adaptor to use.
By the way most if not all centrifugal pumps require larger pipe diameter on the inlet than on the outlet regardless if the pump inlet and outlet connections are the same size.
So in summary do not design your piping system based on the connections of the pump.
Holmez221b
New member
Sounds good.... If my inlet from my sump will only accommodate a 3/4 pipe will it still be benificial to plumb after the pump with 1"
or 1 1/2".
or 1 1/2".
Holmez221b
New member
I meant outlet from my sump
Holmez221b
New member
What size pipe do you recommend from the pump to the display tank?? Thanks for your help...
Holmez221b
New member
The return bulkhead on my display tank is 1"..... Would that kill the flow really bad if I plumb in 1 1/4 or 1 1/2 inch
kiowascout
New member
I ran 1.5 all around on my mak-4 it is then teed off into two 1" pipes right before entering the tank.
The pump pushes the water vertically 13' and horizontally 22' with a smaller 1/2" pipe run teed off and run to the fuge which is 5' vertical and 8' horizontal.
I get plenty of flow (I'd) day at least 800gph in the main tank) at all points in the system and I dont even have the master ball valve on the outlet side of the pump opened all the way.
The pump pushes the water vertically 13' and horizontally 22' with a smaller 1/2" pipe run teed off and run to the fuge which is 5' vertical and 8' horizontal.
I get plenty of flow (I'd) day at least 800gph in the main tank) at all points in the system and I dont even have the master ball valve on the outlet side of the pump opened all the way.
Holmez221b
New member
I have a 55 gallon display tank , 50 gallon sump 30 gallon refug. I have one 1" standpipe for my overflow, it's drilled.
jdieck
New member
Sorry I should have asked about the drain from the begining.
If all you have is a single 1" drain you can handle a maximum of 600 gph.
The Mak4 will handle over 750 gph with a pipe as small as 3/4" dia return as it is a pressure rated pump.
I think the pump is oversized for that overflow, you may want to install a valve on the outlet as you may have to restrict the output but that will increase the water temperature and potentially use more power. Alternatively to save some power and heat you may consider changing to a Mag Drive 9.5 or 12
If all you have is a single 1" drain you can handle a maximum of 600 gph.
The Mak4 will handle over 750 gph with a pipe as small as 3/4" dia return as it is a pressure rated pump.
I think the pump is oversized for that overflow, you may want to install a valve on the outlet as you may have to restrict the output but that will increase the water temperature and potentially use more power. Alternatively to save some power and heat you may consider changing to a Mag Drive 9.5 or 12
Holmez221b
New member
I planned on using a ball valve to adjust the flow. My fliteration is in the basement about 12 vertical and 10 horizontal. So I just wanted to make sure the pump had enough power to make it back to the display
I ran 1" from my Mak4 to the display, then split to (2) 3/4" in the overflows. I have ~ 10' vertical to the 180G display. The dual corner AGA overflows could keep up, but the water level was right at the top of the (too small) slits. I have a separate fuge, so I bypassed some of the return flow to it to cut back the display flow some. Still plenty of flow. Too much if anything.
