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Where Is The Knowledgable Pump Customer Service…

02/27/2017 12:24 PM

Started this discussion out of frustration and vent a little bit.

I had to replace a centrifugal pump for our CIP unit. The model of pump was an obsolete model from PACO.

Our Maintenance manager requested if I could to replace it with one of our Waukesha pump standards C218 or a 2085. It’ll keep our replacement stock down with a standard.

Pump curves with horse power ratings used to be pretty easy to find, but recently I’ve been having problems locating it.

Well after a while, I did find one that meets the Ft/HD and GPM for 20 HP. It was in the upper limits. Unfortunately, I didn’t save it, but knew it could be done with a 20 HP. It was in the high end, but no problem.

I called, gave them the specification requirements, and told them I did a quick research and give them the size of pump I found. They laughed and responded, we’ll see.

The salesmen call me and say, a 20 HP is not going to work and told me a acronym I wasn’t familiar with called NOL BHP and that I would require a 50 HP pump. I told them to run it anyways, a 20 HP would work. I saw it on a pump curve.

I had (2) process engineers call back or email me, one from Waukesha Distributor and one from Waukesha plant engineering. Telling me it’s not going to work.

I was taken aback and asked how can this be?

I admit, I did not understand what they were saying about NOL BHP or why they I felt they didn't understand my requirements.

So after I hung up, I looked up NOL and found out that NOL BHP is a combination of two acronyms that stand for non-overloading brake horsepower. NOL BHP is the maximum power required for a pump to operate at any point along its performance curve.

Along with this, I also noticed it seemed they were spec’ing out larger HP pumps. I used to work for a G&H/Triclover (Now Alfa Laval) Master Distributor.

What does this mean,… I used an example off of Fristam pump curve, not complete but will suffice.

Well once you place your requirement;

  • GPM and Pressure (Red Cross, 25 HP motor would do it.)
  • and find the curve (impeller Dia. Left Blue Circle) ,
  • it spec’s the motor though out all of its performance curve, through the high end. (Right Blue Circle, Customer Service spec'd out a 50 HP motor.)

Again, I just used a Fristam pump curve because it was easily available

I notice they use PUMP-FLO software, maybe these engineers don't know how to read a chart? Its like they no longer spec out for your needs, but over kill it.

Have any body noticed this?

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#1

Re: Where is the knowledgable pump customer service…

02/27/2017 12:47 PM

Have a look at this calculator....are you taking all these factors into account?

http://checalc.com/calc/pump.html

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#2
In reply to #1

Re: Where is the knowledgable pump customer service…

02/27/2017 1:06 PM

Yes, of course,... What your missing is you size the pump to the system curve... not to match the system the maximum of the pump curve.

My point being as an example, when it falls under a 25HP range to do the job of 200GPM @ 160 ft Head, what go beyond that. at , Why 800 GPM @ 120 ft HD.

It ridicules, because the system curve in the process can't handle it.

In this case, The process system itself is physically located is 30 ft above the pump the air with 12 spray nozzles designed at say 65 PSI (after you subtract the 30 ft head for process elevation), at 200 GPM. 16-18 GPM/nozzle.

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#3
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Re: Where is the knowledgable pump customer service…

02/27/2017 1:17 PM
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#4
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Re: Where is the knowledgable pump customer service…

02/27/2017 1:31 PM

I just never heard of NOL before,... and if left unchallenged, there are oversized motors to the pumps being spec'd out.

I'm going to have to specify that the spec's are for the system curve next time,... because over specifying the pump can really raise hell to the system.

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#5
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Re: Where is the knowledgable pump customer service…

02/27/2017 2:20 PM

"In This Application, there is a 7 1/2 Horsepower Requirement at the Duty Point, but the Non-Overloading Horsepower is 15"

..." If you really know your application and are sure that the pump will always run at what you have chosen as your duty point, using a non-overloading motor may be overkill and not necessary. A good example of this would be a pump that has a flow orifice downstream of it that will always restrict the flow rate. But if you think there may be times when the flow rate of the pump will run out the curve for short period (think starting up a pump when the lines are empty), choosing a non-overloading motor can be cheap insurance."...

https://hollandaptblog.com/2014/06/13/what-is-non-overloading-motor-power-how-does-it-affect-sizing-your-sanitary-pump/

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#6
In reply to #5

Re: Where is the knowledgable pump customer service…

02/27/2017 2:59 PM

Agreed, That's where the system curve is the basis of sizing a pump.

I have designed systems with modulating valves,... when that happens, I'll size a pump so its not at the border limits.

But to have a pump sized out with the HP that is capable of flow rate 4 times the requirement is ridicules.

Also, in past pump curves, they use to add efficiency of the pump, similarly to the HP rating.

But it seems pump curve graphics are getting really basic (if any are readily available to the pubic in the first place) and less information to them.

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#13
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Re: Where is the knowledgable pump customer service…

02/28/2017 8:59 AM

You are right, it seems the pendulum has swung the other way. In industry in the last 40 years, we would often find motors tripped out on overload because something in the process changed, a throttle valve left open, some piping change.

It used to be to get the job, the pump suppliers would size to the exact system requirements specified by the customer, because that was the lowest cost. Then some large industrial customers realized they were spending a lot of money and lost production time changing out pump motors, the bases would be too small, coupling spacing too short, the friction losses lower than expected, customer hydraulic design calculations incomplete. So many started specifying motors to run the pump out on the impeller curve, but usually starting close to the BEP, so not a huge investment like you are looking at. So in doing that, retrained some of the pump suppliers, perhaps a little too much, so now it appears to be a knee-jerk reaction with little basis in fact.

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#14
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Re: Where is the knowledgable pump customer service…

02/28/2017 11:52 AM

One needs to have planned ahead. We did an expansion about 3-4 years ago on a cooling tower. As I was sizing it, I was on a trip to the plant on the company plane with one of the owners and we were talking. He found out I was sizing the cooling pumps and he said, nonchalantly, "I can't give you the specifics, but whatever you size increase it by 50%."

I did.

But even if you expand a process, the pump curve does not change; one can easily check to see if the current specs of the pump can match the new system curve.

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#7

Re: Where Is The Knowledgable Pump Customer Service…

02/27/2017 8:15 PM

I can understand why a pump vendor would be reluctant to sell such a grossly oversized pump, even allowing for simplicity of spares inventory.

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#8
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Re: Where Is The Knowledgable Pump Customer Service…

02/27/2017 8:26 PM

You can understand? How? Or you can't understand?

The other thing,.. This may be semantics, the pump isn't oversized, the motor is.

I was talking to our plant engineer, and he mentioned he noticed that Waukesha was oversizing the motors when he'd asked to spec'd out.

as I mentioned earlier, I used to size the out earlier in my career. And when I started working for the company were I'm at not, the plant engineer, told me that not my job, and to let the supplier do that. And only supply the requirements, but from now on, I will add specs for the systems curve.

its just this is the first time noticed NOL.

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#9
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Re: Where Is The Knowledgable Pump Customer Service…

02/27/2017 8:50 PM

The reason the vendor is oversizing the motor is that the pump is oversized in the first place. It's kind of a CYA thing, of course, but the pump supplier can't guarantee that the end user has taken adequate steps to ensure that the pump won't run too far to the right on its curve.

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#10
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Re: Where Is The Knowledgable Pump Customer Service…

02/27/2017 10:08 PM

That's the problem with incompetent engineers and sales, they cya to ridicules measures. Why have them and instead have one size fits all.

With the acceptance of this practice, they are spending so much time and effect and other people's money covering their incompetent asses, that if this is what engineers are coming down to, they are no longer engineers but just place holders.

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#11
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Re: Where Is The Knowledgable Pump Customer Service…

02/27/2017 11:14 PM

ridicules ≠ ridiculous

effect ≠ effort

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#12
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Re: Where Is The Knowledgable Pump Customer Service…

02/28/2017 7:17 AM

Thanks

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