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?

 

[Walter2992]

Thanks to everyone for your contributions. It seems that the orientation is not that important, or at least not likely the cause of the problem. I will follow up with the manufacturer though.

 

[Artisi]

SNORGY, the cut water can be anywhere, top, bottom, side - doesn't make any hydraulic difference.

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]

Believe the thinking is an air pocket possibly being trapped in the pump. It could be easily expelled if the cutwater was at the top. Not so easy if it's at the bottom.

 

[SNORGY]

1gibson:

Yes, that was what I was trying to explain, in a poor fashion. It is based on a "once upon a time" experience that I had years ago with a vertical in-line condensate stabilizer reflux pump. At a certain percent open on the reflux pump discharge flow control valve, there was a significant drop in throughput to the column that I read using a Polysonics Doppler Meter. There wer no audible signs of cavitation, and at the flow setting coincident with column pressure, there ought not to have been a capacity problem. When I (with the Operator) opened the pump casing drain to qualitatively assess the nature of the liquid, we found that it was rapidly boiling off even when we dumped a 45-gallon of Northern Alberta January snow on the suction piping. What I decided to do, right or wrong, was tie a restriction orifice / needle valve / tubing installation from the casing vent back to the reflux drum vapour space, with a view towards being able to allow any broken-out vapours to be expelled. This change, after a suction piping optimization and the installation of a flow-inducer imeller in the pump, provided enough incremental performance improvement to achieve the desired reflux rate.

Regards,

SNORGY.

 

[Artisi]

Air within the casing can be a problem and having said there would be no hydraulic difference, which is true, the cut water under ideal conditions should be at the top to assist in self-venting.

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]

Just to define the term "conditions," under ideal fluid conditions the cutwater could be anywhere. Under real world fluid conditions, it should be at the top if possible.

In an ideal situation, it should be at the top.

 

[chicopee]

My question on the OP is have the values been compared to the pump performance and the system curves at the temperature of the water being pumped?