Horiz. split case v. vertical turbine (thread 164-80905) 2

[eddieng27]

(I probably should have posted this question in this forum first)
Can anyone steer me to a good resource that actually lists pros and cons of horizontal split case centrifugal and vertical turbine pumps-specific not just general? I'm primarily interested in operations and maintenance, performance, efficiency, space requirements, ease of operation, bearings, motors, wear, repair, maintenance, owner/ operator preference based on ???, etc., with heads and flows of 300 ft and 5,500 to 7,800 gpm (90 m & 30,000 m^3/day to 42,500 m^3/day) ... I'm in a discussion with another colleague about an upcoming design project. He prefers horiz. split case centrifugals and I prefer vertical turbines. Maybe someone has a reference that actually documents maintenance activities, frequencies, and their associated costs. What about systems that changed out one type of pump for another?(thread164-80905)

 

[Artisi]

The application can also be a contributing factor in the selection.
What is the application?



Naresuan University
Phitsanulok
Thailand

 

[eddieng27]

Two situations, both municipal treated potable water, fed by a gravity tank, one discharging directly into a residential area distribution system, and the other discharges into a several thousand-foot long transmission main before that pipeline connects to a residential area distribution system. Both pumping facilites pump to gravity storage tanks. These situations are very typical of most all of the pumping facilities I have designed before; some with associated clear wells and some in-line stations. I have also used multi-stage vertically mounted centrifugal pumps on occasion (lower flows about same 300-foot head). My colleague has typically designed larger flow pumping facilities, but generally municipal potable water supply/ distribution applications

 

[rmw]

Where will you take suction? The horizontal split case may have to have a priming mechanism if the suction is taken from below pump CL. That is one advantage of a vertical pump. You get the pump suction down where the suction comes from.

rmw

 

[Artisi]

As for an answer to what is the best unit based on maintenance requirements etc I don't really have any preference as there are for and against points both units.

My decision would be based on the application and the construct costs for this project, and as the supply to the pump inlet is from gravity tanks I would select the HSC pumps - easier to install and less civil works.

If on the other hand some of your projects are pumping from wet wells I would probably lean towards the vertical pumps.

To me - the decision would be based on capital costs, including real estate - equipment and the best hydraulic (efficiency) selection for the duty.

Naresuan University
Phitsanulok
Thailand

 

[eddieng27]

In both upcoming cases, suction piping will enter the pumping station from below grade. At the point of entry, the suction piping manifold could obviously accommodate various configurations for the HSC or VT pumps (clearwell or cans). My colleague is confident that the pump's NPSHR can be met by the situational NPSHA (even at 6,000 ft elevation).

I agree with all of your comments, but do you know of a definitive source that lists these types of pros and cons? I guess the equipment manufacturers really don't care which pump they sell, so I'm not sure they would be the source of information I'm looking for. A manufacturer, however, might be a good source if they have accumulated this type of pro/ con information where they have either experienced great satisfaction with their products or dissatisfaction, even to the point where their equipment was replaced (VT for HSC or vice versa, or even by a competitor's pump).

 

[Artisi]

Sorry - I can not guide you to a source which lists the pros and cons for each pump style, but feel sure any of the major pump companies will be happy to give the best advise they can based on the application and the best hydraulic fit they have for each of your application.

Naresuan University
Phitsanulok
Thailand

 

[KernOily]

A lot of times it comes down to maintenance and operations skill and availability. Both pumps can be made to work and selected to work. In my experience, in high-head applications e.g. 3500' TDH and more, most folks around here (central California) use horiz split-case because the local repair vendors around here have historically done crappy jobs on repairs and installs of vertical turbines. In my experience, a horiz pump, esp. an API 610 type, is more forgiving of a poor installation esp. in regards to the foundation, baseplate, and alignment of interconnecting piping. They seem to be more operator-friendly in the way of attention to seal flush systems and bearing lube systems. Horiz pumps have a lower oper and maint cost life cycle and history vs. vertical turbines in the same service. Just my experience.


Thanks!
Pete

 

[Artisi]

74Elsinore (Petroleum)

for a duty of 3500ft TDH it would be very unlikely that a VT would be available for this application anyway.
As for comparing horizontal pumps to vertical pumps - a lot depends on what you are comparing - the difference between high quality VT and Horizontal pumps would be minimal - however, if you are comparing agricultural / irrigartion quality VT pumps then your comments would be correct. Quality VT pumps can be designed for a service life of 15 - 20 years without too much difficulty as can HSC pumps.

Naresuan University
Phitsanulok
Thailand

 

[nickelkid]

VT pumps work well when you need to add NPSHa but at a higher cost for civil design/construction. Either design can provide dependable non-stop service when designed well.

 

[BigInch]

I only use VT only when there is no other way to get NPSH.

BigInch-born in the trenches.

http://virtualpipeline.spaces.msn.com

 

[KiwiMace]

I'm currently trying to work around a design for VT pumps that we put together, but our VT pump quotation doubled by the time it became a bid. We will be looking at raising our sump and cooling towers to reduce the suction head for split case centrifs.

I think the VT pump guys think that if you spec these pumps it is too late for any alternatives.

 

[dcasto]

VT are used in other special circumstances, cryogenics, where a sealess design is required, and loading applications.

 

[poppeye]

When comparing VT to HSC on the maintenance end. A HSC will need more periodic maintenance, ie. bearings, seals or packing, couplings etc. The VT if using standard shafting not Enclosed tube will virtually need zero maintenance over the service life of the pump. The largest draw back of a VT, is when they go down, turn around time is normally 2-3 times that of a HSC. Plus a lot of initial engineering to remove motor & pump from the pit. A HSC can be serviced by just removing the top casing and rotor leaving lower casing and motor and piping intact.