Pump Curve

A system curve or a performance curve?

"The system head visualized in the System Curve above is a function of elevation - or the static head and the major and minor losses in the system and can be expressed as:

h = dh + h_l (1)

where

h = system head (m)

dh = h₂ - h₁ = elevation (static) head difference between the inlet and outlet in the system (m)

h_l = major and minor head loss in the system (m)

A generic expression of major and minor head loss is:

h_l = k q² (2)

where

q = flow rate

k = constant describing the total system characteristics - including all major and minor losses

Increasing the constant - k - by closing some valves, reducing the pipe size or similar - will increase the head loss and move the system curve upwards. The starting point for the curve - at no flow, will be the same."

"

Pump Performance Curve

The pump characteristic is normally described graphically by the manufacturer as the pump performance curve. The pump performance curve describes the relation between the flowrate and the head for the actual pump. Other important information for a proper pump selection is also included - like efficiency curves, NPSH_r curve, pump curves for several impeller diameters and different speeds, and power consumption.

Increasing the impeller diameter or speed increases the head and flow rate capacity - and the pump curve moves upwards.

The head capacity can be increased by connecting two or more pumps in series, or the flow rate capacity can be increased by connecting two or more pumps in parallel."

http://www.engineeringtoolbox.com/pump-system-curves-d_635.html

http://www.waterworld.com/articles/print/volume-25/issue-1/departments/pump-tips-techniques/creating-an-accurate-pumping-system-head-capacity-curve-first-step-towards-reducing-energy-consumption.html

https://blog.craneengineering.net/how-to-read-a-centrifugal-pump-curve

You don't.

You cannot "build" a pump curve. A pump curve "builds" itself as the result of tests performed by a competent pump technologist.

You have a LOT to learn!

Read this: Pump system curve - Mc Nally Institute

Take a ten pole motor, pitch a name plate on it with a fake certificate number, let it run for a moment driving a pump of your choice, make up numbers in Excel and publish it as a graph.

This could be called a commercial fraud and can only be found out by maintaining diligent quality control.

True. There should be a sort of acceptance test prior to turning over, especially for fire pumps and other sorts similar.

Wow! I didn't know they were making motors (in the Phillipines) out of tent poles.

I am saying he can build his pump curve as follows (for all the good it will do him):

1) mark the flow rate at zero horsepower, and record the pressure with it.

2) record the horsepower, flow rate and pressure with the nominal sized suction and discharge ports, with no bends in the various pipes, and no constrictions.

3) with the output blocked, run the pump, record the horsepower (right before the motor burns up, or the MCC trips the breaker), and record the pressure. Assume a reasonable flow rate for a completely blocked outlet.

4) draw a straight line through your three data points. If you cannot draw a straight line, then welcome to the real world. Sketch a curved line, and embellish it as needed with flourishes.

I think there's a flaw in your test procedure.

3) A blocked outlet won't fry the motor since the load will be reduced far below normal output.

The pump may destroy the seals or housing if plastic.

Either way the OP is in way over his "head"!

Ya get it? Pump? Head? Pump head!

Pump curve components are supplied by the same mob that provide additional power bands for IC engines.

They do however need very specialised technicians to install and are often cheaper to obtain as part of a new device at purchase.

A Pump Curve are the results that are derived from empirical data based on a reference. Usually water at 70°F, sometimes 60°F, or 55°F

...and there is no need to <...build...> one, as it is done already by the pump manufacturer. It may be found in technical sales literature for the pump in question, and also as a technical datasheet, both of which are produced by these organisations for the purpose of selection in conjunction by the end user.

Always remember that the operating point is where the pump curve and the system curve intersect.

Talk to your rep.

You shape it like this:

1/ Usually, the pump curve is provided by the manufacturer.

This curves can be interpreted as a commitment of the manufacturer of the parameters are required (committed) with the products they manufacture.

For example, a pump (already produced) to the H-Q curve, has Duty Point DP(H = 3.6m; Q = 3.5m³/s). When operating the pump at Q = 3.5m³/s if Pump Total Head is H = 3m. We conclude unsatisfactory pump.

To assess the pump curve, we can apply the ISO 9906: 1999 (2012) (Rotodynamic pumps - Hydraulic performance acceptance tests - Grades 1, 2 and 3) ...

2/ In case you have your pump, but lost the pump curves, you can build curves empirically pump (pump operation, collect the data and redrawn pump curves)

*** My problem

I get pump curve from the commercial department of a major manufacturer.

There are many indications that the curve has been changed.

I need the knowledge to be able to build the pump curve (same manufacturer) to be able to check the curves it on.

Moreover, I need the method to calculate the vibration, noise, "runout point" of the pump.

Your contribution will help me make the right decision when selecting a pump

Thank SolarEagle, you have a good article to use the pump curve, but it is not what I need

What would be "many indications that the curve has been changed"?

That post is complete nonsense.

Published on the website

Many and many

Give customers (27/01/2016)

Give customers (27/01/2016)

So? The first curve doesn't look related to the others at all. In any event, if the operating ranges are different, then the curves will be different, but not necessarily changed. In the third diagram, what's that nonsense about 36>40?

These are 3 of the same pump curve (same type, same weight, same mouth suction, the discharge mouth, same number of blades, same blade angle, same density of the liquid ...)

"36> 40" is the distributor

N times the pump in parallel does not mean N times the flow.

The operating point remains where the system curve and the three-pump curve intersect.

Your imagination is quite rich.

1 / The whole forum is no such word as "parallel" or "serial"

2 / If the pump is not connected to the system (piping) then have not operation point (Duty point)

You should reread post of SolarEagle and post of lyn (Read this: Pump curve system - Mc Nally Institute)

And you are saying that between the OEM published curves, and the actual physical pumps shipped there are differences? OMG what a big shock (that is not). The telephone call to the distributor usually makes the final decision over what pump is actually shipped. In centrifugal pumps, the impeller clearance may be increased to make a more reliable pump when the discharge head is not critical issue surrounding the application.

It seems you have not really understand the pump.

* Quote "Sulzer Technical Review 1/2016" - Poux-Guillaume Greg - Sulzer CEO.

* Or: ISO 5199:2002 - Technical specifications for Centrifugal pumps - Class II

Article 3.2 allowable operating range

range of flows or heads at the specified operating conditions of the pump supplied as limited by cavitation, heating, vibration, noise, shaft deflection and other similar criteria

NOTE The upper and lower limits of the range are denoted by maximum and minimum continuous flow.

* and tolerances: Rotodynamic pumps - Hydraulic performance acceptance tests - Grades 1, 2 and 3 (ISO 9906:2012)

So...other than showcase your self-assessment of superiority here, what is it you actually want?

You are really taking a liking to that cartoon, yes?

It is sort of funny to see the varied applications thereof.

I don't know yet what techpump's issue or problem he needs help with is, it seems he only issues enough information to the forum to permit him to smack everyone down on the next round, and I am about done with it,

Actually When I found it I thought it was funny and use it kinda like an emoji.

so better be nice, or I'll go Batman on you with a 'Bat Slap'... wait... I already did earlier this week, didn't I?

Yeah, I still have the batprint from it. Just wait until you are bent over under the hood of the Batmobile...

oh, oh...

Riddler: Count me in