9 replies to this topic

[process_engg]

Hi All,

I have very basic Question. While designing a pump we fill the data sheet with following data....
1) Flow rate Normal, Rated
2) Temp, Viscosity, Density, Vap Pressure
3) Suction Max pressure, Suction press.
4) Differential Pressure.

My Question is We do not deliver any pump curve and Control Valve pressure drop while making data sheet, Then How Vendor start designing pump.

Thanks in advance...

Process engg.

[Art Montemayor]

process_engg:

When a pump manufacturer receives a copy of my specification sheet - as the one I include for centrifugal pumps in the attached workbook - I can assure you that he/she will have no problems quoting and supplying a pump that will meet or surpass the stated expected performance.

Contrary to what you state, a manufacturer does not start designing a centrifugal pump the moment he/she receives your specification sheet or a request for bid. If this is done, it would be for a very, very special design or capacity pump - which is not the normal case. A recognized and reputable pump manufacturer has already designed the pump you are going to receive. In fact, the pump is probably already manufactured and sitting on a shelf ready to ship.

All manufacturers design and build a variety of pump models designed to fit a variety of applications. Be realistic and practical. If anyone were to be sitting around waiting for you to decide to buy a pump of certain specifications before they start to design it, they would starve to death. They cannot design each pump specification they receive; the resulting price would be astronomical and non-competitive with other manufacturers. Your pump specifications should fit a certain model of frame and casing size and the applied impeller will be trimmed to yield the resulting performance. That's the way the business is operated world-wide.

Note how my specification sheet contains a LOT of more required information than your post.
 Art__s_Process_Spec_Sheets.zip   188.81KB   187 downloads

[Qalander (Chem)]

Splendid info Thanks Art.
You are genuinly helping and guiding to many in need.

[process_engg]

Thanks four your elaborate explanation Art.

I have still one Query in my mind.

While we send our Pump datasheet to vendor, we do not send System Curve and Control Valve pressure drop, then without these two information How pump vendor select the pump curve?

[Qalander (Chem)]

Thanks four your elaborate explanation Art.

I have still one Query in my mind.

While we send our Pump datasheet to vendor, we do not send System Curve and Control Valve pressure drop, then without these two information How pump vendor select the pump curve?

Dear

I feel there is a lot in the Art's sheet basically,however Any pump is always selected ensuring/having sufficient head to cover and fulfill system needs.

Accordingly it is nothing extra to be metioned/specified normally.

[Zauberberg]

While we send our Pump datasheet to vendor, we do not send System Curve and Control Valve pressure drop, then without these two information How pump vendor select the pump curve?

As explained by Qalander, this information is specified by required differential head (or discharge pressure) which should be delivered by the pump, within the requested flow ranges.

[sheiko]

Thanks four your elaborate explanation Art.

I have still one Query in my mind.

While we send our Pump datasheet to vendor, we do not send System Curve and Control Valve pressure drop, then without these two information How pump vendor select the pump curve?

process_engg,

The following link proposes a free software that helps you optimizing your pump calcs (namely pump + control valve systems). It is called PSIM:
http://www.pumpsyste...px?id=110<br />
Plus, a little description of it:
http://www.plantserv...s/2007/041.html

Rgds

[djack77494]

While we send our Pump datasheet to vendor, we do not send System Curve and Control Valve pressure drop, then without these two information How pump vendor select the pump curve?

Normally neither we nor the pump vendor cares about the pump curve. We want a pump that will deliver the required flowrate against a predetermined pressure. When we specify the required capacity and head (or differential pressure) for a centrifugal pump, along with supporting process information, then we have given the pump's vendor everthing he/she needs to select one of the pumps they manufacture for our purpose. Depending on how the pump is built, its characteristics (read curve) will vary, but typically we don't really care. So no one selects a pump curve. We specify the requirements and select a pump that meets or exceeds those requirements. If we have other requirements, they may lead to choosing the type of pump that would be suitable, but even then we are not selecting the curve, merely the characteristics.

[ARAZA]

Dear All,

I agree with djack77494.

To reply to Qalander on the control valve pressure drop. The vendor does not care about the control valve pressure drop, the pump designer while calculating the TDH (total dynamic head) of the pump had taken into account the control valve pressure drop which is about 1/3 of the total dynamic loss.

The pump vendor typically needs the TDH, rated flow and physical properties of the fluid, % solids, design temperature and NPSH available (based on preliminary layout) to quote.

Regards,

ARAZA

[Qalander (Chem)]

Dear ARAZA,
Probably you have mis-understood my comments about system requirements;which almost covers everything i.e our needs of flowrate(s) and minimum pressure(head) needs at discharge.

Control valve and any other hydraulics or system local pressure needed to be catered all form part of the above referred needs definitions.