Restricted Suction - External Pump

[niccumec]

I have a Sicce SDC 9 pump capable of 1000-2500 gph. I want to maximize the flow potential so I am transition to a large 2” outlet return pipe, minimizing head/fittings/elbows/etc. Using the online friction calculator, I can easily determine the approximate friction loss. No issues there…. Where I am confused is on the intake of the pump. Since I am running external, I will have to flow through a bulkhead in the sump. Sizing the intake is the question for this post.

Referencing the popular online flow charts, I see that gravity flow / suction side of pump would only allow 960 gph for 1” and 2,100 for 1.5”. The Sicce pump has 1” inlet and outlet. I emailed Sicce and they responded that a 1” bulkhead would be fine for 2100 gph…???

These two sources conflict. I do not want to starve the pump and restrict rate and/or cause cavitation. What am I missing? Do the flow charts above not apply to “short” run sections of pipe? Not a big deal to drill large holes for bigger bulkheads, but don’t want to upsize unnecessarily. Will look kind of funny with huge 1.5” / 2.0” bulkhead an true union valves coming out of sump return section.

 

[MarineandReef Jaron]

I have a Sicce SDC 9 pump capable of 1000-2500 gph. I want to maximize the flow potential so I am transition to a large 2” outlet return pipe, minimizing head/fittings/elbows/etc. Using the online friction calculator, I can easily determine the approximate friction loss. No issues there…. Where I am confused is on the intake of the pump. Since I am running external, I will have to flow through a bulkhead in the sump. Sizing the intake is the question for this post.

Referencing the popular online flow charts, I see that gravity flow / suction side of pump would only allow 960 gph for 1” and 2,100 for 1.5”. The Sicce pump has 1” inlet and outlet. I emailed Sicce and they responded that a 1” bulkhead would be fine for 2100 gph…???

These two sources conflict. I do not want to starve the pump and restrict rate and/or cause cavitation. What am I missing? Do the flow charts above not apply to “short” run sections of pipe? Not a big deal to drill large holes for bigger bulkheads, but don’t want to upsize unnecessarily. Will look kind of funny with huge 1.5” / 2.0” bulkhead an true union valves coming out of sump return section.

Sicce is correct. The flow chart you have referenced is 960 GPH for a gravity drain however this is not a gravity drain it is a pump intake.

 

[niccumec]

Sicce is correct. The flow chart you have referenced is 960 GPH for a gravity drain however this is not a gravity drain it is a pump intake.

That is what is confusing me. That table also states “Gravity… also suction side of pump” for that 960 gph. It’s just really hard to believe that a small 1” bulkhead and piping to pump won’t be overly restrictive at high rates. I do not believe these types of pumps “pull” water in so it does feel more like a “gravity” feed to me.

 

[DCR]

There is no way you will get 2100 gph through a 1" suction line. Even the gravity flow of 960 gph is really not realistic. If you want to maximize the flow, run a 2" suction line and reduce dow.n with a reducer bushing right at the suction connection. Do not expect to get 2100 gph even with this.

 

[niccumec]

There is no way you will get 2100 gph through a 1" suction line. Even the gravity flow of 960 gph is really not realistic. If you want to maximize the flow, run a 2" suction line and reduce dow.n with a reducer bushing right at the suction connection. Do not expect to get 2100 gph even with this.

That is what I was thinking. Interesting that they market a 2,500 gph pump and design with 1" inlet/outlet connectors. All I can do is minimize restrictions to maximize the pump flow capability.

 

[niccumec]

FYI... I challenged Sicce's initial response on 1" inlet being acceptable. They forwarded the question from sales to technical support and are now recommending to upsize the inlet as we have just discussed. They think 1.5" may even be enough. Besides looking silly with a 2" bulkhead and Ball valve, it certainly cannot hurt to maximize flow.

Pumps are much more expensive than pipes and fittings, it does not make sense to me to restrict a perfectly good (and expensive) pump.

 

[KStatefan]

That is what I was thinking. Interesting that they market a 2,500 gph pump and design with 1" inlet/outlet connectors. All I can do is minimize restrictions to maximize the pump flow capability.

That is all you can do.
The 2500 is rounded up from the 2377 on their charts which is at zero head that really does not help.