Understanding Pump Curves for KSB Pumps – Made Simple
Let’s be honest. The first time most people look at a KSB pump curve, they feel overwhelmed. Lines everywhere. Numbers everywhere. Efficiency percentages. Power curves.
It looks complicated.
But here’s the truth: once someone explains it properly, a pump curve is actually very simple. And more importantly — it’s one of the most powerful tools you have when selecting a KSB pump.
Let’s break it down in plain language.
What Is a Pump Curve Really Showing You?
A pump curve is just a graph that shows how a pump behaves under different conditions.
It answers four important questions:
- How much water can the pump move?
- How much pressure can it create?
- Where does it run most efficiently?
- How much power will it use?
Think of it as the pump’s performance map.
The Two Things That Matter Most: Flow and Head
On every KSB pump curve, you’ll see two main measurements:
- Flow (usually in m³/h)
- Head (usually in meters)
Flow is the volume of water moving through the system.
Head is the pressure — or how high the pump can push that water.
Here’s the key principle:
As flow increases, head decreases.
That’s simply how centrifugal pumps work. It’s normal behaviour.
What Is the KSB Duty Point?
Your system has requirements. It needs a certain flow and a certain pressure.
Where those two requirements meet on the curve is called the duty point.
That point is everything.
If the pump can operate comfortably at that point, your system will run smoothly.
If it can’t, you will have ongoing problems — even if the pump is high quality.
The Best Efficiency Point (BEP) – The Sweet Spot
Every pump has a “happy place” on the curve. It’s called the Best Efficiency Point, or BEP.
At the BEP:
- The pump runs smoothly
- Vibration is minimal
- Bearings and seals last longer
- Energy consumption is optimised
When a pump operates too far away from this point, things start to go wrong.
You may see:
- Excess vibration
- Higher electricity bills
- Shorter seal life
- Bearing failures
The closer your duty point is to the BEP, the healthier your pump will be.
What Happens When the KSB Pump Is the Wrong Size?
This is where many problems begin.
If the Pump Is Too Small
If it cannot reach the required head at the required flow:
- Pressure will be low
- The system underperforms
- The pump works too hard
It struggles constantly.
If the KSB Pump Is Too Big
Many people think bigger is safer. It’s not.
An oversized pump often means:
- You throttle it back
- You waste electricity
- It runs away from its efficiency point
- Components wear out faster
Bigger does not mean better. Correct means better.
Why Pump Curves Actually Save You Money
When a KSB pump is selected properly using the pump curve:
- Energy usage is lower
- Maintenance reduces
- The system runs more reliably
- The pump lasts longer
When selection is based on guesswork, problems are almost guaranteed.
The pump curve removes guesswork.
A Simple Way to Understand It
Think of it like driving a vehicle.
If you drive in first gear at high speed, the engine screams.
If you try to climb a hill in top gear at low speed, it struggles.
There’s a comfortable cruising range where everything runs smoothly.
That’s the Best Efficiency Point for a pump.
Why This Is Important for KSB Pumps
KSB provides detailed pump curves for every model — whether it’s an Etanorm, MegaCP, or multistage unit.
Those curves are not just technical paperwork. They are there to ensure:
- Proper selection
- Long-term reliability
- Energy-efficient operation
When you understand the curve, you stop guessing and start making informed decisions.
Not Sure How to Read Your Pump Curve?
If you have:
- A required flow rate
- A total dynamic head calculation
- Or a pump curve that doesn’t make sense
It’s always better to confirm before installing.
At Pumps Africa, we help customers across South Africa match the right KSB pump to the correct duty point.
Because fixing a pump selection mistake after installation is always more expensive than getting it right the first time.