Double Suction Pump Efficiency Claim 93% 2

[stanier]

I have a vendor who is claiming an efficiency for a double suction centrifugal pump as high as 93%. No other vendors can make this claim. Has anyone experience of this type of pump with such efficiency?

Duty is 8416 gpm at 367ft.

Geoffrey D Stone FIMechE C.Eng;FIEAust CP Eng

http://www.waterhammer.bigblog.com.au

 

[Artisi]

It's achievable - but if you doubt the claim ask for witnessed performance testing with a penalty for under performance.
Who's pump is it (or give me a clue or two - just the size and model number might be sufficient)

Naresuan University
Phitsanulok
Thailand

 

[25362]

There is an interesting graph to predict efficiency as function of specific speed (Fig. 3) in Pump Handbook by Karassik et al, (McGraw-Hill).

 

[stanier]

Nijhuis from the Netherlands Venus 1-400650. Unfortunately their website doesnt have any detailed curves or selection software.

As for penalties if they dont perform thats fine except you dont know by how muc it will not perform and it could cost you big bucks over the life of the project.

Geoffrey D Stone FIMechE C.Eng;FIEAust CP Eng

http://www.waterhammer.bigblog.com.au

 

[Artisi]

I have no experience with Nijhuis - so cannot make any worthwhile comments re their pumps etc.

As a matter of interest, is the 93% the pump only effic. or the overall pump / motor efficiency.

Any penalty can be calculate over the life of the project or 10 years or what ever you consider a reasonable time period. It is just a matter of comparing the calculated power consumption, say at per 1000 litres, using the guaranteed 93% Pump efficiency against the actual power consumption per 1000 litres at the guaranted point on test. Any short fall is the penalty per kWh /1000 litres to be pumped over the penalty period.

Likewise any increase in efficiency should be a bonus to the supplier using the same criteria.



Naresuan University
Phitsanulok
Thailand

 

[WebWizz]

There is a good calculator on the web:

http://engineeringpage.com/engineering/pumps.html

and choose Centrifugal Pump

Using this calculator it predicts a pump efficiency of about 90% (.894), so 93% looks just possible to me. Driver efficiency is excluded from this figure. The vendor has a good reputation so I agree with the comment earlier made to do a performance test - good idea for such a big pump anyway.

 

[smckennz]

Hi Geoff

wasnt expecting to find you here. 93 is on the high side.
The number needs to be referred to the proposed test method, as some codes favour the vendor. It is not unusual for the measurement accuracy to be the decider on efficiency. For example, if the test code permits an accuracy of 5% on head measurement (and some do), then you do not have grounds for rejection if the computed efficiency is 88%. If you want shop performance tests, be sure to get the cost first as they can be dear. Liquidated damages for underperformance should always be imposed if outright rejection is not an option. The liquidated damages are normally calculated on an NPV or lifecycle basis. But they should be included on the spec (e.g. $XXX per percentage efficiency point).

Surprised you arent going for TKL.

Cheers

Steve

 

[Artisi]

Like wise- it the project is in Aust. TKL would be a good choice.
Still interested in knowing if the 93% is pump effic. or pump /motor effic.

Naresuan University
Phitsanulok
Thailand

 

[rmw]

Is the quoted pump efficiency with or without packing/seal losses? Sometimes vendors will cheat and rate the pump as if it has no seals. Same with couplings if they are furnishing a package.

Read the fine print.

rmw

 

[stanier]

Thanks guys,

The problem is I am reviewing the data sheets and the quote. The data sheet didnt specify whether the efficiency was based on HI, APi or ISO 9906 (Grade 1 or 2). It didnt nominate whether the seals were included in losses. I presume it didnt include for motor losses either.

I was just wondering if anyone knew the manufacvturer and any tricks that may be used. I have the heads up on a re enquiry, what to specifgy etc to get everyone on a level playing field.

Steve, As for Australian supply, TKL is an old favourite but now they are owned by Flowserve they are not considered an Australian company. Loyalty only goes so far.

ABS tell me they have a paper pump with 98% efficiency in their sales brochure but it is all about how you measure it!

"Oils aint oils,Sal", to quote a successful Esso advertisement

Geoffrey D Stone FIMechE C.Eng;FIEAust CP Eng

http://www.waterhammer.bigblog.com.au

 

[Artisi]

Geoff
I would check if the motor in in/excluded as this will make a big difference to the o/a power consumption. As this is a European manufacturere I would assume they are using the ISO test code - which was adapted for use in Aust.

The ABS pump mentioned is more than likely one of the Scan Pump (Sweden) paper stock fan pumps - these are very accurately manufactured to very rigid tolerances always multi vane and sometimes a combination of end-suction open impeller and closed impeller within a single impeller always expensive but necessary for the role they need to fulfil.

Could be worth a look as power cost can certainly run to a lot of money over a 10 year period.

Naresuan University
Phitsanulok
Thailand

 

[doncas]

The US Dept of Energy's PSAT program, which uses Hydraulic Institute (HI) algorithms to estimate maximum commercially available efficiencies for pumps,indicates a top-of-the-line efficiency of 92% for a double suction pump operating at 8416 gpm, 367 ft.

However, the HI committee that is responsible for the standard used by PSAT is in the process of revising the achievable efficiency values. My guess is that the new standard, which should be out in the next few months, will result in a slightly lower value than the current version, as standard committee members recognized that the efficiencies for some pump styles (including double-suction).

By the way, PSAT is available for free download from the DOE at:

http://www1.eere.energy.gov/industry/downloads/software_tools/psat.zip

 

[ccfowler]

stanier,

I've always found it best to study quotes and proposals with much intensified attention when claims strain the bounds of credibility. A good concept to keep in mind is one that I learned many years ago:

Performance data is generated by the Engineering Department, edited by the Marketing Department, and glamorized by the Sales Department. At each stage, no one falsifies the data, but they do find ways to present it in the most attractive manner.

Translation:

Pay very close attention to all fine print, keep industry standards in mind, and pay close attention to the potential width of allowable error bands for parameters.

From my experience, it is a rare vendor that will not provide useful clarifications when asked pertinent, well founded questions. In reality, bonus/penalty adjustment provisions commonly get very messy to adminster due to site conditions, off-optimum operation, less than perfect provisions for pressure, temperature, and flow measurements, etc.

In this particular case, it is almost a certainty that motor, seal, and coupling losses are not included in the 93% figure.