Vertical In Line Pump Installed Horizontally 1

[Walter2992]

I am Civil/Structural, but as an Owner's representative am involved with all aspects of building design and construction. We have a situation where a vertical in-line pump has been installed in a horizontal position. This is a 1/2 Hp pump that serves a primary boiler loop. The design flow is 48 GPM at 15 ft. head. The pump is providing 42 GPM at a delta P of 8.7 ft. Could this reduced flow be due to the pump orientation?

 

[Artisi]

No.


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.)

 

[JJPellin]

I agree with Artisi. It is more likely something else. You did not provide enough information to answer the implied question.

Possible causes:

Excessive wear ring clearance.
Excessive impeller lift.
Plugged suction strainer.
Inaccurate flow meter.
Inaccurate pressure gauges.
Calculation error: Wrong specific gravity.
Calculation error: Failure to properly compensate pressures for elevation.
Inadequate NPSH available (pump is cavitating)
Pump not properly piped.
Pump not properly vented and flooded.
Open or leaking spill-back line.
Leaking check valve on spare pump installed in parallel.
Inadequate submersion on suction (air ingestion).
Impeller diameter does not match the curve.

I'm sure that there are several hundred other possibilities. If you can provide more details, we might be able to shorten the list.


Johnny Pellin

 

[pennpiper]

Get a representative from the Pump Manufacturer's technical group to come to the site and check out the installation and ask him (or her) to offer some opinions as to why you are having reduced performance problems with their pump.

Be prepared to explain (and defend) why the "Vertical In-line Pump" is not installed in the "Vertical".

 

[Pumpsonly]

If it is pumping hot water, the reduced DP could be due to cavitation..If you have discharge valve installed try throttling it to reduce the flow rate and see it the Dp goes up to the published curve head.

 

[SNORGY]

I am thinking it might well be partly due to pump orientation. I am thinking that most people don't normally install a vertical in-line pump horizontally. If that was regular practice, then presumably, someone would have alrewady cornered the market on "horizontal in-line pumps". This sounds like a retrofit into crowded piping, confounded by an unconventional pump installation. I would be looking to see if there is vortex formation potential, gas entrainment or other things that might be giving rise to some vapour fraction in the pump volute, and the volute, due to its orientation, is having difficulty expelling the bubbles whereas it otherwise wouldn't.

To me, the reduction in performance is not so "horriffic" that it can't be explained, at least in part, by poor overall pump installation and orientation. It's a small pump; it probably wouldn't take much to make it work poorly.

But...that's just me...and I'm not a pump guy.

Regards,

SNORGY.

 

[electricpete]

What is meant by "in-line" pump?

Is it simply in-line with the fluid system? (that would seem to cover almost all pumps except perhaps eductor types).

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(2B)+(2B)' ?

 

[electricpete]

maybe it means that the discharge piping is paralle to suction piping rather than perpendicular?

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(2B)+(2B)' ?

 

[electricpete]

Found this picture of "in-line vertical"
There is no vertical piping, but shaft is vertical

http://www.cranepumps.com/products/typeInlineVertical.php

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(2B)+(2B)' ?

 

[pennpiper]

electricpete,
Yes, that picture shows a typical "vertical in-line pump"
The shaft of the pump is vertical with the motor on top.
The pump suction nozzle is on the right.
The pump discharge nozzle is on the left.
There is no piping shown.

Just a side note:
Many people believe that the "Rule" for this type of pump is it does not need a foundation for support or stabilization (resistance to starting torque). They believe the pump can be supported by the suction and discharge piping.
The "Exception" to this is the size/weight of the pump vs. the size of the piping. There is also the question 'how do you support the pump when you need to remove some part of the piping or valves for maintenance?'

Google "Vertical In-Line Pumps" and you will see thousands of links, some of which show pictures. Here is one of the best links:

http://www.flowserve.com/files/Files/Literature/FPD/ps-10-28-e.pdf

 

[electricpete]

Thanks pennpiper. My question is answered.

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(2B)+(2B)' ?

 

[Artisi]

A vertical in-line pump can also be installed as a horizontal-inline pump.

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.)

 

[electricpete]

To summarize the defintion of "in-line", I gather it means the suction and discharge are in-line with each other.

With the relatively flimsy construction shown in the links and highlighted by pennpiper, it seems that moment associated with the weight of the motor hung on the side of the pump casing could introduce distortion which might affect centering of impeller with respect to stationary parts.... could it affect the fluid performance?

(Of course there are many other possible reasons for apparent degraded pump performance as eloquently described above).

At any rate, I'd wonder about the long-term reliability when installed in this fashion.

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(2B)+(2B)' ?

 

[Artisi]

Just one example

http://completewatersystems.com/product-type/in-line-pumps/

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.)

 

[electricpete]

Thanks Artisis - some in-line pumps seem designed for either orientation. But do you think it applies to all in-line pumps?

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(2B)+(2B)' ?

 

[Artisi]

No, the motor support from the case would be a priority for horizontal mounted configuration.

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]

This is only a 1/2 hp pump, I believe the vast majority of inline pumps that size can be installed either vertically or horizontally. But it's worth confirming.

 

[Artisi]

I would agree that pumps of this size would be interchangeable - but worth checking.

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.)

 

[DubMac]

The pump Walter2992 is talking about, the 1/2HP variety, is known as a circulator. They pump water in HVAC/hydronic applications. They are close-coupled; that is impellers mounted on the motor shaft. There is no worry with these tidbits oriented any way you want.

It is a huge mistake to think that this applies across the board with all vertical inlines. If you cannot pick the pump up and toss it 25 feet, DO NOT install it any other way than vertical; and that being with the motor on top.

.

 

[SNORGY]

OK, I didn't think this through in all dimensions...

Horizontal orientation with vertical upflow might work. I was thinking more about horizontal orientation with horizontal flow and the cutwater at the bottom of the pump; that might not work quite as well.

Thanks Artisi. Learn something new every day.

Regards,

SNORGY.