When you think of the cost of a pump, what comes to mind first?

Most likely, the initial investment cost. Yet, this is only the beginning of the story. When it comes to industrial pumps, the largest cost factor is not the purchase itself, but the energy the pump consumes throughout its entire lifetime.

Surprising but true: a full 85% of a pump’s TCO comes from energy costs. This proves just how much of a difference the right pump selection and operational strategies can make in the long run.

To boost energy efficiency and eliminate hidden costs, we need to focus on these two golden rules. Let’s take a closer look at them together…

All pumps are designed to perform optimally around a specific duty point (a combination of flow rate and pressure). This point, where the pump operates at its highest efficiency, is called the Best Efficiency Point (BEP).

The BEP cone is the hydraulically stable and highly efficient operating range defined around the BEP on the pump’s characteristic curve, typically covering a flow range of ±10–15%.

Operating a pump far from its BEP leads to energy losses, hydraulic instability, and severe failures.

Regions outside the BEP cone are where the pump’s hydraulic balance is disrupted;

• High temperature
• Cavitation
• Vibration and noisy operation
• Backflow & recirculation
• Reduced seal and bearing life

These are inefficient operating zones where failures and energy losses increase.

Therefore, from every perspective, keeping the pump’s operating point as close as possible to the BEP is the optimal choice for equipment longevity, product quality, and process safety.

One of the traditional methods for flow control, throttle valves, unfortunately leads to significant energy waste. Let’s examine the use of a throttle valve versus a VFD for a given duty together.

First, we selected our pump for this duty, and now let’s look at our alternatives when a lower flow rate is needed.

In a scenario without a VFD, the only way to reduce a pump’s flow is by increasing the pressure.

The way to do this is by installing a “throttle valve” at a point on the pump’s discharge line, decreasing the flow area to increase the pump’s head, and throttling until the desired flow is reached on the pump’s characteristic curve.

In a scenario using a VFD, adjusting the frequency via the VFD will achieve the same task.

• When 50 TPH ➡️ 40 TPH;;
• 50Hz ➡️ 40Hz

For the same conditions, the line pressure drop: 5 bar ➡️ 3.3 bar (This is not possible with a throttle valve; the pump operates along its own curve).

• 10,8kW ➡️ 4,9kW

An incredible energy saving.

Let’s consider two different duties (e.g., long-term low-flow production and short-term high-flow CIP cleaning).

• Duty 1: 70,000 L/h – 5bar
• Duty 2: 45,000 L/h – 2bar

For such an application;

• Can we handle it with the same pump?
• What kind of pump should we choose?

So, when selecting a pump…

1. Should we select it based on the maximum capacity?
2. Or should we select it based on the minimum capacity?

• Duty 1: 70,000 L/h – 5bar
• Result: VFD:50 Hz / Power consumption 13.85 kW

• Duty 2: 45,000 L/h – 2bar
• Result: VFD:32 Hz / Power consumption 3.64 kW

• Duty 1: 70,000 L/h – 5bar
• Result: VFD:60 Hz / Power consumption 13.62 kW

• Duty 2: 45,000 L/h – 2bar
• Result: VFD:38 Hz / Power consumption 3.50 kW

In centrifugal pump systems, the steps to reduce TCO and increase operational efficiency are quite clear:

• Analyze your operational requirements and select the pump model closest to the BEP.
• Prefer VFDs over throttle valves for flow control.

Remember, technology and the right engineering approach are the most effective ways to optimize your operating costs. The cheapest pump is the one that consumes the least energy and operates most efficiently.

So, what steps are you taking in your operation to reduce these energy costs?