How Fill Mechanical Data Sheet for a Pump covering 2 different operation condition?!!!!!

[Sabergg1981]

Hi All,

I am wondering about how to fill out API mechanical data sheet supposed to cover 2 different operation condition? in the other hand, we have a 2+1 condensate transfer pumps with specified conditions . but this pump's capacity will be different after 5 years. how it can be?

 

[TD2K]

I've provided two sets of conditions in the past, call it initial and future or whatever terms you use and see what the vendors propose and then see if you agree with their proposal considering the initial and final operation.

Without some more information to the system, controls, etc it's hard to get much more specific.

I had a system where we were offloading tank cars through a common line, we had to design the system from one pump oto three running in parallel. With the line losses, I knew the discharge pressure was going to vary enough to worry me. We summarized the information and sent it out for proposals. While we got proposals back, when we looked at the proposals and curves we ended up having to install a backpressure control valve as none of the centrifugal pumps could handle the range of discharge pressures without running off the end of their curves. Just don't accept the vendors' proposals, you need to look at them in light of your system and its design.

 

[DubMac]

Pumps are designed and sold for only one GUARANTEED operating, or design point. That is typically the "design" point on the data sheet with the "normal" point being a secondary condition, but not guaranteed.

Of course that is not to say a manufacturer can't give any additional assurance for the remainder of the performance curve; but it has always been the practice of manufacturer's to guarantee one point.

 

[Artisi]

After 5 years it might be time to think about upgrading the unit/s to something more suited to the new pump duty - plus you haven't indicated current and future hydraulic duties, so how do expect to get any meaningful feedback.

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.)

 

[Pumpsonly]

You still can specify the 2 conditions by using the remarks / Note at the bottom of the sheets.
Let the vendor work out how can they met these conditions...There are many options depending on the conditions

1) by impeller change--bigger or samller
2) By adding or removing impellers if it is multi-stage pumps-- casing and motor based on the most stringent requirement.
3) Using VFD..

It all depends on the changes required.

Before you issue the formal inquiry, you better talk to some vendors first to make sure it is workable.

 

[SNORGY]

I just use two data sheets, and on each data sheet I state that:

"This pump is one and the same pump as is specified on (the other) data sheet, so it must perform satisfactorily at each service condition."

 

[DubMac]

Two data sheets is probably the best approach. Just make sure there is a clear understanding of the "performance guarantee" within the contract documents. Many vendors have written into their standard T&C's that only one point will be guaranteed.

 

[Artisi]

The second data sheet should be marked-up as anticipated future duty or some similar statement to safeguard your pump selection in the future. Only guarantee 1 duty point which should be for the initial duty.


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.)

 

[m2609]

I assume this is a centrif pump, API 610? You should specify the worst’s case condition, i.e. highest head and flow, once you receive the pump curves from the pump supplier you should check that any other operating conditions the pump may need to work in fall within the limits of the curve, i.e above the minimum flow requirements (unless you have a recycle). As DubMac has said above the pump supplier will only guarantee one operating point, and the supplier should select the pump and impellar size which has this one operating point as close to the BEP as possible.

You should also ensure the pump supplier shows the min and max impeller curves on the proposal curve, as for your year 5 case you may want to the impellars so you can operate nearer the BEP.

 

[m2609]

Ops, Trim the impellars!

 

[stanier]

Most respected pump companies have selection software avaialable. What I would do having to hand initial bids is to use the suppliers software to investigate how the pump will perform over the range of anticipated duties. Then meet with the pump supplier to discuss the findings. If agreement can be reached as to how the pump will perform establish a guarantee point for the contract. Then ensure the pump has tight test requirments and witness the testing.

Yes you may have to trim the impellers, fit a larger impeller or adjust the flow control valves in the system in the future. Pipes may age but they may also be cleaned or replaced. Future process duties are notorious for being wrong. The "future" as you see it now may not be what it is when it occurs!

“The beautiful thing about learning is that no one can take it away from you.”
---B.B. King

http://waterhammer.hopout.com.au/

 

[Artisi]

Seems as though the OP Sabergg1981 has vanished anyway- so we are now spinning wheels.

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.)