Questions About Head loss calc

[DarkFORCE]

I am trying to build a CLM for my 90g tank. I am using the head loss calc on this site and don't quite understand it.

http://www.reefcentral.com/calc/hlc...Couplings=2&CheckValves=0&Exits=8&Entrances=1

Total losses are 11.12 feet of head pressure, or 4.8 PSI. with a flow rate of 911 GPH. Process took 60 iterations


Does this mean I should get arounf 911gph from each exit in the loop?

 

[DarkFORCE]

anyone?

 

[Bryan89]

No, total system flow should be 911 gph from the pump. To lower the head loss, use Spa Flex instead and make gradual turns.

Or, use 1.5" plumbing instead which in theory raises your flow to 1876 gph.

The simple way to explain headloss is friction in a pipe. If you go with a bigger pipe (from 1" diameter to 1.5" diameter) you more then double to area for flow and greatly decrease the velocity of the fluid, thereby decreasing the frictional losses.

Tried not to answer like an engineer.

I am curious as to why you want to use 8 exit points. This will also add to your head loss.

HTH

Bryan

 

[Putawaywet]

Just talking out loud here but everytime I think about that calculator I can't help but wonder how accurate it can be when there are so many darn variables that factor into hydrodyanmics.

Wouldn't excess glue built up inside a joint throw it off? Or pipe that wasn't cut straight or seated fully into a fitting thus leaving a noticible gap? Pipe with a burr on the ends? Wouldn't stuff like that all be an issue that could throw off the accuracy? Especially factored across 20 or 30 fittings? and if so, how much of an error factor could that wind up being... 10%? 20%? 30%?

I understand that it's probably intended as more of a guide than anything else, but I have long wondered if it was designed to factor in a bit of wiggle room for things like mentioned above or does it calculate based solely on the assumption of perfect unions.

Brett

 

[Bryan89]

As I said before, it is a theoretical calculation. I do not know how accurate it really is or what sort of uncertainties the calculator has in it. As you stated Brett, a bad day on the manufacturing line may leave a burr on a union, but it may or may not significantly affect the flow through the pipe based on a lot of other dynamic flow characteristics which are not modeled in the calculation.

The calculator is useful IMO to check the sanity of what you are building, as in if I get a result 0 gph of flow off a pump, my setup is simply not going to work.

Bryan