Trash Pumps - Suction and Discharge Hose Length?

[Beltzington]

After years of trolling CL I finally found and bought a lightly used 4" 13HP commercial grade pump for a great price. No hoses were included and looking online I was disappointed the see the hoses can run a few hundred dollars. Purpose of the pump will be pond maintenance with the intent of trying to clean sediment from the inlet without having to drain the pond completely which would be my last option. I have read several technical write-ups for determining hose length but like most they fall short of making general recommendations. What combination of hoses provides the most suction, I need at least 100' of total length? Do I go with a 10' suction section and 90' of discharge or 25' suction and 75' discharge? Only need to pump the sludge over a 6' high bank.

Pump performance is attached, see "F."

 

[Egon]

Make the suction as short as possible.

 

[mrmikey]

Make the suction as short as possible.

Yup, and since suction hose has to be rigid to prevent collapse and discharge hose can be flat it's going to be the cheapest solution....Mike

 

[Travelover]

I do something similar with a 3" pump. I made a suction hose out of a ten foot piece of 3" PVC. Since I'm just pumping over a berm, I made a very short discharge that just lets it blast into the air. The flat PVC hose is not that expensive - about $150 for 100 feet.

 

[speedbump]

You do intend to use 4" suction don't you?

 

[Beltzington]

You do intend to use 4" suction don't you?

Yes.

Thanks for the responses, discharge hose is certainly less expensive.

Could someone in layman terms explain why the inlet hose length effects the pumping capacity more the outlet length assuming both are the same diameter?

 

[bcp]

The outlet has the full power of the pump pushing it. The inlet only has atmospheric pressure.

You can pump uphill hundreds or thousands of feet. You can only pull uphill a little over 20 feet maximum vertical distance.

Bruce

 

[Beltzington]

The outlet has the full power of the pump pushing it. The inlet only has atmospheric pressure.

You can pump uphill hundreds or thousands of feet. You can only pull uphill a little over 20 feet maximum vertical distance.

Bruce

There you go, it took you two sentences to explain what wasn't clear in two pages of formulas. Thank you!

Now that you cleared that up let me further confuse the issue

As long as the pump doesn't cavitate due to low inlet pressure, inlet through-put will match outlet correct? If this is true, discounting friction, than a 20' suction hose would work just as well as a 5' hose, this isn't entirely academic as using a short suction hose will mean I will need to float the pump on the pond as opposed to leaving it on the bank.

 

[Streetcar]

There you go, it took you two sentences to explain what wasn't clear in two pages of formulas. Thank you!

Now that you cleared that up let me further confuse the issue

As long as the pump doesn't cavitate due to low inlet pressure, inlet through-put will match outlet correct? If this is true, discounting friction, than a 20' suction hose would work just as well as a 5' hose, this isn't entirely academic as using a short suction hose and will mean I will need to float the pump on the pond as opposed to leaving it on the bank.

You have some losses from longer hose due to friction, but the big loss is from change in elevation.
I have used 75 feet of suction hose in the past

 

[Beltzington]

Will suction hoses connect to each other?