head pressure question with 90's

[Dweezilz]

This may be a newbie question but I just got a new Sicce Syncra SDC 6.0 return pump for my RS Reefer 250 and I'm having some trouble dialing it in. My old Eheim Compact+ 3000 was dialed in at it's max perfectly which came with the used system when I purchased it 2 years ago. When calculating head pressure on a Reefer 250 which has the return going straight up about 43" to the outlet, do I count the 90 degree right turn at the outlet nozzle exit in the head pressure calculation? So should that 90 degree count as 1 foot of head pressure, 1/2 or 0? Also I do have a locline dual nozzle (open ends, no random flow generator). Not sure if that counts in the calculation either. My pressure is probably either 3.5' or 4.5' which is considerable difference since that's either 1056 or 898 GPH. I'm running it at 67% now but I think that's too much and I should be closer to 50% or maybe 40% if that 90 doesn't count.

Thanks for the help!

 

[HBtank]

Pressure Drop / Head Loss Calculator

Plastics Pipe Institute Inc. (PPI) calculator for estimating pressure drop or head loss in plastic pipes.

www.plasticpipecalculator.com

 

[Dweezilz]

Pressure Drop / Head Loss Calculator

Plastics Pipe Institute Inc. (PPI) calculator for estimating pressure drop or head loss in plastic pipes.

www.plasticpipecalculator.com

Thanks. Not to be ungrateful, but I know how to calculate head pressure but that doesn't really answer my question to be honest. I really just need to know if that 90 degree right at the nozzle exit counts as a 90 degree. I don't know if that Y in the nozzle counts as anything either and the calculators don't really tell you that part.

 

[HBtank]

All fittings will add to the equivalent length calculation for headless

 

[HBtank]

PVC Pipes - Equivalent Length and Pressure Loss in Fittings

Minor loss in PVC and CPVC fittings expressed as equivalent length of straight pipe.

www.engineeringtoolbox.com

 

[Dweezilz]

PVC Pipes - Equivalent Length and Pressure Loss in Fittings

Minor loss in PVC and CPVC fittings expressed as equivalent length of straight pipe.

www.engineeringtoolbox.com

Sounds good. Thanks again. I will count those two things so I guess I'm be closer to being good at 67% than I thought. 55%-60% is probably best and I'll be somewhere around 6X. Now I'm probably around 8X. Just trying to figure out why it's harder to dial this thing in than the Eheim was.

 

[KStatefan]

I depends on the velocity of the fluid on how much headloss the 90 makes. That is why the equivalent length is used

Pump Calculator | Pentair AES

Pentair is dedicated to excellence in all aspects of our business. Whether you need system design, technical service or unrivaled equipment-you can count on us.

pentairaes.com

 

[Dweezilz]

I depends on the velocity of the fluid on how much headloss the 90 makes. That is why the equivalent length is used

Pump Calculator | Pentair AES

Pentair is dedicated to excellence in all aspects of our business. Whether you need system design, technical service or unrivaled equipment-you can count on us.

pentairaes.com

What does the equivalent length mean as far as a 90 degree? I'm pretty well studied after 2 years of reading and videos etc...but there's still a ton I don't know about. So much to learn!

 

[KStatefan]

Look at the link @HBtank posted. You use those numbers to add to your length of pipe then calculate the headloss due to friction in the pipe then add that to the vertical head to get the total headloss.

 

[Dweezilz]

Look at the link @HBtank posted. You use those numbers to add to your length of pipe then calculate the headloss due to friction in the pipe then add that to the vertical head to get the total headloss.

Yeah, I just realized that looking at the chart again before you replied. So according to that a 90 degree is equivalent to 2.1 feet if my pipes are 3/4". I'm not quite sure what that 90 is on a red sea but it seems small more like 1/2" or a bit more. I guess if 1/2" it would be 1.6 feet added. Why do I keep reading elsewhere that a 90 degree adds 1 feet. BRS says that too.

 

[Dweezilz]

I just read that the red sea return 90 degree elbow is 10mm or 0.39" so probably around to 1.2 to 1.3 feet added.

 

[KStatefan]

Yeah, I just realized that looking at the chart again before you replied. So according to that a 90 degree is equivalent to 2.1 feet if my pipes are 3/4". I'm not quite sure what that 90 is on a red sea but it seems small more like 1/2" or a bit more. I guess if 1/2" it would be 1.6 feet added. Why do I keep reading elsewhere that a 90 degree adds 1 feet. BRS says that too.

The friction head loss in a pipe is variable with the velocity and is not a fixed number. With that chart you add those number to the length of pipe you have ie 2 1" 90 fitting and 2 45 1" fittings and 6 feet of 1" pipe gives you a total of 14 feet that you would use to calculate the friction headloss with and then add that to your vertical height difference to get the total head loss.

Or just use one of the calculators to get you close enough.

 

[Dweezilz]

The friction head loss in a pipe is variable with the velocity and is not a fixed number. With that chart you add those number to the length of pipe you have ie 2 1" 90 fitting and 2 45 1" fittings and 6 feet of 1" pipe gives you a total of 14 feet that you would use to calculate the friction headloss with and then add that to your vertical height difference to get the total head loss.

Or just use one of the calculators to get you close enough.

Makes sense now. I think I'll use the calculator and get close! Thanks for all the info...a big help for sure!

 

[Dweezilz]

The friction head loss in a pipe is variable with the velocity and is not a fixed number. With that chart you add those number to the length of pipe you have ie 2 1" 90 fitting and 2 45 1" fittings and 6 feet of 1" pipe gives you a total of 14 feet that you would use to calculate the friction headloss with and then add that to your vertical height difference to get the total head loss.

Or just use one of the calculators to get you close enough.

Just thought of one last question. Since the Red Sea has a green flexible tubing for 22" from pump to bottom of the pipe that's 3/4" and then into a tapered nozzle connector and then into the 21" hard pvc pipe going up that is 0.98" (I'll use 1" for the calc) with the calculator do I have to use two separate measurements or is using the calc going to be slightly difficult because of the two different pipe sizes. For now what I did was do two calculations. One for just the soft tubing and no 90's or T's at 3/4 and then another with 1" and 1 90 and 1 Tee and then adding them together. Is that going to get close? Then the 90 elbow is back to 1/2" as well.

 

[DCR]

There is additional head loss from sudden contractions and expansions. The barbs add a lot of pressure drop because the ID is even smaller than that of the tubing. The Loc-lines do the same thing. anywhere there is a change in diameter will introduce additional pressure drop. It is very difficult to apply these calculators to our systems because so many of the fittings are not in the calculator. I generally say that you should not expect to get much more than 300-400 gph through any significantly long section of 3/4" tubing or 600-700 gph through 1". By significant, I mean anything more than a fitting or short section of pipe less than about 6". There is no way you will get 900-1000 gph through that system but I don't see why you need it for a Reefer 250.

 

[Dweezilz]

There is additional head loss from sudden contractions and expansions. The barbs add a lot of pressure drop because the ID is even smaller than that of the tubing. The Loc-lines do the same thing. anywhere there is a change in diameter will introduce additional pressure drop. It is very difficult to apply these calculators to our systems because so many of the fittings are not in the calculator. I generally say that you should not expect to get much more than 300-400 gph through any significantly long section of 3/4" tubing or 600-700 gph through 1". By significant, I mean anything more than a fitting or short section of pipe less than about 6". There is no way you will get 900-1000 gph through that system but I don't see why you need it for a Reefer 250.

Yeah, definitely don't need it. Red Sea recommends 660GPH. The Sicce Synca SDC 6.0 does 1450 max vs. my previous Eheim which did 730 (or whatever) max. That one was easy...full blast since it was so low anyway. I currently have the Sicce at 67% but it's so hard to say what that results in. If my head is 6 feet then it's about 740 at max and at 4 it's about 1000 max before loss. I know it probably doesn't really matter all that much but I'd like it to be close.

 

[KStatefan]

There are so many variable in calculating the value you could go for ever getting into the weeds on this. If you really want to know get a flow meter.