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?

 

[crackerjack222]

Suction hoses will connect together but you should put the pump as close to the water's edge as you can. this is so the lift on the inlet side of the pump will be as little as practical. You will get better performance with as little lift as possible. If you only want to pump the level down a few feet, say 4 feet, a 20 fot suction hose should be enough as long as you have a good place to locate the pump where it will be stable and you can get to it. The suction hose will need to have a foot valve at the end so you can fill it and the pump with prime water. Another reason to keep the suction hose as short as possible.

 

[Streetcar]

Will suction hoses connect to each other?

They can connect if you have the same type of end connectors
Is your pump self priming

 

[Travelover]

I'd just add that the seal on the inlet side has to be perfect all the way from the pump to the water. One little pinhole leak and it will not prime. On the discharge side, it will just leak water.

 

[EddieWalker]

When I bought my 3 inch pump, I found that Northern Tool had the best prices and selection for hoses. I went with them for all of it and I don't have any complaints. The suction hose isn't very long. I have a strainer at the end of it that I bought from Northern Tool also. I have three dishcharge hoses. I'm guessing each is 100 feet long. I might be way of on that. I rarely use it. The discharge hoses are soft fire hose looking things that roll up and don't take up any space at all. The suction hose is a pain to deal with because it's rigid and heavy.

 

[speedbump]

The biggest mistake people make with suction or discharge is bushing down in size. This adds a tremendous amount of friction and your pump will become a small pump with a large engine.

 

[buickanddeere]

Pumps are built to push, not pull. Pump suction port must be as low and as close to source as possible .

 

[Sawyer Rob]

The biggest mistake people make with suction or discharge is bushing down in size. This adds a tremendous amount of friction and your pump will become a small pump with a large engine.

True, but sometimes I don't need a big exhaust hose to get the job done,

so I use a more "manageable" size that works perfect for the job at hand!

SR

 

[valley]

Hi, Haven't read every post. the exhaust host can be that cheap floppy junk hose, anything. The pick up hose, depending on where you're working can be partially ABS or PVC. There is s flex PVC that I have on the HOT TUB that works perfectly and can be glued to the any PVC if you have some in Line. AND you can use male or female PVC or ABS fittings to connect to your Trash Pump.

The pick up and lift all depends on your pump.

Have a great day.

Richard

 

[buickanddeere]

Hi, Haven't read every post. the exhaust host can be that cheap floppy junk hose, anything. The pick up hose, depending on where you're working can be partially ABS or PVC. There is s flex PVC that I have on the HOT TUB that works perfectly and can be glued to the any PVC if you have some in Line. AND you can use male or female PVC or ABS fittings to connect to your Trash Pump.

The pick up and lift all depends on your pump.

Have a great day.

Richard

Have you looked at the flow and pressure curves of pumps with various suction heights ? How far can you make a pump "lift" ?