DIY spraybar

[Shadowcat3]

Anybody out there know the proper way, if there is one, to calculate hole size and numbers for a DIY spraybar......Yeah, I know, you just keep drilling holes till it looks right.....Surely one of you physics majors out there can calculate this and come up with a formula for velocity and flow rate vs. hole diameter and numbers....Or do I just keep drilling holes??

[Wasserpest]

I'd assume the answer would differ ... depending on if this is for a ZooMed 501 or a Fluval FX?

[epicfish]

Originally Posted by Wasserpest

I'd assume the answer would differ ... depending on if this is for a ZooMed 501 or a Fluval FX?

Not only that, but do you want even flow through all the holes, etc, etc...? If so, the spacing wouldn't be even.

KISS....just keep drilling until you get what you want.

[Shadowcat3]

Yeah, just keep drilling, who needs all that silly math anyway It would be useful to know how to balance the flow from the holes for a reasonably uniform output though.

[gmccreedy]

Good rule of thumb is to drill enough holes (in area) to be equal to the area of the hose going into the spray bar.

For example, 1/2" (0.196 sq in) tube feeding the spraybar, requires (16) 1/8" holes (1/8" hole has an Area = .0123 sq in) to equate the same area.

This is not an exact science, but enough for you to start with.

[gmccreedy]

Originally Posted by Shadowcat3

Yeah, just keep drilling, who needs all that silly math anyway It would be useful to know how to balance the flow from the holes for a reasonably uniform output though.

Split the inflow tube and feed from both sides of the spray bar, not one side.

Or.... progressivly reduce the size of the holes the further you got away from the source. (compensate with velocity to account for the reduction in area since flow is getting slower accross the length of the spray bar).

[Hoppy]

As long as the total area of the holes is less than the area of the inside of the pipe they are drilled in, you should get reasonably uniform flow from every hole. The less that total hole area is relative to the pipe inside area, the faster the flow from the holes, until the holes area is about equal to the pipe area, then the flow velocity from the holes is about the same as in the pipe. If the holes area is greater than the pipe inside area, the flow from the holes will not be uniform, and the farther away the hole from the inlet the lower the flow from that hole. I know you can make the total holes area equal to about 80% of the pipe inside area and it works well for uniform flow from each hole.