Vertical vs. Horizontal Submersible Pumps

[ApplicationENG]

Can someone explain the operational/design advantages/disadvantages of horizontal (OH1 style) submersible pumps when compared to typical well-type vertical submersible pumps?

 

[Artisi]

Please explain what a OH1 submersible is?

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[TenPenny]

Horizontal submersible pumps have a lot more issues with the bearings in my experience. Not that we've done any OH1 style submersibles, but the multistage vertical turbines that we've seen used horizontally are generally a hassle.

 

[ApplicationENG]

See link (Pg. 2 - KRT Wet Well / Dry Well):

http://www.ksb.com/linkableblob/ksb...USA_Pumps_Mixers_Production_Brochure-data.pdf

I am talking only to single stage submersible pumps.

Any additional information?? i.e. advantage of low liquid levels, vibration, seal life, etc.

 

[Artisi]

If you are comparing the KSB vertical to horizontal using the same wetend I can't see any difference/advantage/disadvantage of either.


It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[1gibson]

Link didn't work for me, but the "1 stage horizontal" type submersible pumps are designated VS4/VS5. They are basically a horizontal pump on a stick (column and lineshaft) with a separate discharge pipe that goes to a surface plate.

Curves will be different, lower efficiency, but the case/cover/impeller should be the same, with some configuration changes on the case (no mounting feet.)

Stay away unless you know exactly how to handle lubrication of the lineshaft bearings. Options are fresh water, oil drip, forced product, or grease. On the other hand, they should be less than 1/2 the cost of a VS1 submersible, so plan accordingly.

Don't use for delicate processes, as the curves are usually very flat and hard to control flow. That may be an understatement; depending on where the rated point is on the curve (usually far left of BEP) it can be a challenge to keep them from running at shutoff. Be very careful using them in parallel, avoid if possible. Due to relatively low cost, you can go 1 x 100% with a spare in the warehouse.

 

[piffer]

Vertical dry-pit submersible pumps are mounted on pedestals (or stand) and include an inlet elbow attached to the bottom of the pump. A horizontal dry-pit submersible pump is installed like a typical end suction centrifugal pump. The inlet conditions are much better (Horizontal- straight shot of suction piping into the pump vs. Vertical- 90 degree elbow into pump, which provides unequal velocity into the impeller eye, unless you use a reducing elbow with a minimum 2-size reduction). In a horizontal configuration, the impeller C-L is at a lower elevation. This can save $$ in construction costs (station depth and operating levels for same NPSHA) when using a horizontal dry-pit submersible pump.
Horizontal dry-pit submersible pumps are available with the motor mounted on a service cart. You can unbolt the motor from the volute (leave volute in place and plumbed) and roll back motor for servicing/inspection. A horizontal dry-pit version seems to have more plusses than the same pump in a vertical version. I think we will see a trend towards horizontally installed submersible dry-pit pumps because of the inherent advantages mentioned.

 

[bimr]

The main reason for stating that it is much easier to maintain a dry pit pump is that with a dry pit pump, the O&M staff can inspect and tell when something is amiss and repair it before the problem becomes too serious. Such inspection is impossible with submersible pumps, because they cannot be observed routinely and must be hauled out of the wet well for repairs. Consequently there is a greater tendency to let the sub mersible pump run until it simply fails. Then the cost of repair is usually very high.


In general,it requires more personnel to remove submersible pumps than conventional dry pit pumps.

Dry pit installations are expensive in first cost but less costly to maintain.

 

[bimr]

Dry pit installations are expensive in first cost but less costly to maintain. Many utilities seem to agree that large submersibles should be confined to dry pits where they can be serviced in place. Personnel generally agree that it is much easier to maintain a dry pit pump.

The main reason for stating that it is much easier to maintain a dry pit pump is that with a dry pit pump, the O&M staff can inspect it and tell when something is amiss and repair it before the problem becomes too serious. Such inspection is impossible with submersible pumps, because they cannot be observed routinely and must be hauled out of the wet well for repairs. Consequently, there is a greater tendency to let the submersible pump run until it simply fails. Then the cost of repair is usually very high.

Submersible pumps are quite variable in frequency of maintenance required. Some agencies have had to pull submersible pumps
as frequently as every 6 months. Others have gone as long as 6 or 7 years before having to pull the pumps for maintenance. The typical interval seems to be about 2 years. Seal and bearing failures are the most common problems with submersible pumps. Damage to power cables and motor windings occur less frequently.

Pumps with externally cooled submersible must be immersed for continuous operation and can run only for short periods of time if exposed to air. Pumps with motors internally cooled by the pumped liquid can be run continuously at full load without immersion. The same is true for some (but not all) oil filled submersible motors. Pumps that can operate dry continuously at full load are also available for dry pit installation. They are not damaged if the dry well accidentally flooded, but this advantage comes at the expense of higher cost of the pump and motor, slightly greater energy requirement (because of less efficiency), and a larger structure (because of the added dry pit).