Estimating Pump Costs Using a Curve

[JonasP]

I'm looking for some guidance on how best to estimate pump capital costs using a cost curve.

We have some numbers already, but my questions is it better to use price vs capacity or price vs hp and the justification. Already we've found that price vs hp is probably more accurate but would like a second opnion.

The pumps are mostly centrifugal single and double suction for water transmission and wastewater collection.

Thanks in advance

Jonas P

 

[JRLAKE]

I may misunderstand the question but I would not make a decision without considering the life cycle cost.

 

[BigInch]

I've always correlated to HP.

Reason being that capacity has no bearing on HP. A low capacity at high head can require the same HP as a high capacity pump at low head, so HP tends to glide through that variance and makes it more reliable than capacity. Since capacity can be all over the place, there is no apparent correlation to the total price of pump plus driver.

JR,
Capital cost does not include operating cost and therefore essentially leaves out much of the life cycle cost differentials. Since most all cost, some 85-90% of all total costs thereafter, is for power consumption cost, I have not found life cycle cost to be very useful in making plant capital cost estimates, as long as any potential efficiency differentials are properly considered in the capital cost.

"I'm all in favor of keeping dangerous weapons out of the hands of fools. Let's start with typewriters."
- Frank Lloyd Wright (1868-1959)

 

[JonasP]

To Clarify I'm not worried about life cycle costs as this is an excercise to determine replacement costs for existing equipment

Thanks for the imput BigInch, I'm satisfied using HP as the parameter.

 

[JRLAKE]

True Big Inch, but I see life cycle costs influencing the capital budget discussions more every day with increasing energy conservation pressures.

It seems silly to me to discuss capital budgets without considering total costs. But then again I admit that I may not fully understand the goal from JonasP's point of view.

 

[BigInch]

No no. I'm saying, if you use curves based on the costs of high efficiency machines, you're doing the best you can do in regard to capital cost estimate. Life cycle costs, EXCLUSIVE of energy consumption, might total a machine's capital cost over its lifecycle, but both of those together only amount to 80-85% of the cost of total energy consumed by that machine over its lifecycle. I assume he's only trying to develop the capital cost estimate now and others will be looking at cost of operation (energy + maintenance) as an adder to his work now.

"I'm all in favor of keeping dangerous weapons out of the hands of fools. Let's start with typewriters."
- Frank Lloyd Wright (1868-1959)

 

[BigInch]

And that operation and maintenance costs, being materials, parts, labor and other's, exclusive of energy cost, doesn't differ sufficiently BETWEEN hi efficiency, medium eff or low efficiency machines to sway one way or another.

"I'm all in favor of keeping dangerous weapons out of the hands of fools. Let's start with typewriters."
- Frank Lloyd Wright (1868-1959)

 

[JonasP]

The purpose of the cost curve was to avoid calling up manufactures for pricing every second day. We have a couple of co-op students verifying asset data for our asset management plan and also determining replacement costs for certain equipment types of which pumps is one of them.

There are lots of pumping stations and even more pumps, so to speed up the process its easier to develop a curve based on a sample of quotes as we are looking for ball park numbers.

If it was for a true replacement we would probably look at it a little differently with life cycle consideration. BigInch is right though, its the energy costs that will generate the greatest cost which comes down to system design not the pump or components themselves assuming they're not lemons.

 

[BigInch]

Optimize the system design, and you've got it licked. Upgrading components in a well designed system is much easier than the other way around.

Unless you've got some biased operating scenarios (predominately high capacity low head, or v/v), you'll make a better curve correlating to HP.

"I'm all in favor of keeping dangerous weapons out of the hands of fools. Let's start with typewriters."
- Frank Lloyd Wright (1868-1959)

 

[BRIS]

Back in the 80's I was producing a lot of feasibility studies for pumping systems and produced curves of total installed power - v - total capital costs. It was surprising how close actual tender costs fitted to the curve ( OK it was an iterative process we used tender data to modify the curves) . Of course you have to compare like with like. A low lift sewage pump station will not fit on the same curve as a booster pump station.

The answer is yes common practice is to build cost estimating curves on installed power. The UK Wessex Data Base (cost estimating price book ) used to have a set of pump sation estimating curves at the back - I don't know if it still does !

 

[stanier]

If you want to really evaluate this why not invest in AFT's Mercury. This software enables you to model your whole system and the financial aspects. It is not cheap but could save a lot of hours and get you the right answer.

http://www.aft.com