Differential pressure is a key concept in many industrial processes. It describes the difference between two pressures measured at different points in a system - for example, before and after a valve, filter or pump. Understanding and measuring differential pressure is essential for ensuring stable flow, optimising performance and preventing process equipment failure. That's why it's an important tool for both technicians and buyers to assess system function and efficiency.

How does differential pressure occur?

In any pipework system, resistance will occur as liquid or gas moves through components such as valves, filters, pumps and heat exchangers. This resistance creates a pressure drop - and it's this pressure drop that we measure as differential pressure.

Examples from practice:

• Over a filter: An increasing differential pressure may indicate that the filter is becoming clogged and needs to be changed.
• Through a valve: The pressure difference tells you how much energy is used to open the valve and maintain flow.
• In a pump: The differential pressure shows how much pressure the pump is adding to the system and is used to control its performance.

Even in a simple pipe run, the friction between fluid and pipe walls will create a natural differential pressure. The higher the flow rate or the more viscous the fluid, the greater the pressure drop - and thus the differential pressure.

Why is differential pressure measurement important?

Measuring differential pressure provides important insights into how a system is performing. Here are some of the most common reasons to monitor differential pressure:

• Optimise flow and process performance: By analysing pressure differences, valves and pumps can be adjusted to make the system run more efficiently.
• Identification of problems: An unexpectedly high differential pressure can be a sign of clogging, leakage or other equipment failure.
• Monitoring the condition of components: For example, a rising pressure drop across a filter can reveal when it needs replacing - without stopping the system.
• Documentation and quality assurance: In processes with high control and traceability requirements, such as in the food and pharmaceutical industries, differential pressure monitoring is an important part of quality management.

How is differential pressure measured and calculated?

Differential pressure can be measured with a so-called differential pressure gauge or transmitter, which records the pressure at two different points and displays the difference. These gauges can be mechanical or electronic - and are often integrated into SCADA systems or process control for continuous monitoring.

The formula for differential pressure:

ΔP = P1 - P2

Where:

• ΔP is the differential pressure
• P1 is the pressure before the component
• P2 is the pressure after the component

In more complex systems - such as those with varying density, flow direction or temperature - the calculation may require corrections and technical insight. But in many industrial contexts, a simple measurement provides a quick and useful picture of system health.

Alflow's solutions for handling differential pressure

At Alflow, we know that proper control and monitoring of differential pressure is crucial for efficient operation and process control. That's why we offer not only components - but also advice and technical sparring when it counts:

• Choosing valves and pumps with the right flow design and pressure loss
• Components for pressure monitoring like sensors, transmitters and flow meters
• System design and optimisation based on operating situation, fluid type and pressure conditions
• Documentation and validation for the food, pharma and process industries

We help ensure that your system works as it should - with optimal energy efficiency, lower maintenance needs and high reliability.

FAQ

What is differential pressure?
It is the difference between two pressures measured on opposite sides of a component - for example, a filter, valve or pump.

How do you measure differential pressure?
You use a differential pressure gauge that connects to two points in the system and shows the difference in pressure.

Why is differential pressure important?
Because it provides insight into flow conditions, energy consumption and the condition of components - and helps detect operational issues early.

How do you calculate differential pressure?
By subtracting the pressure after the component from the pressure before. For example: 3 bar - 1 bar = 2 bar differential pressure.

What can a high differential pressure mean?
This can indicate that a component is clogged or that there is resistance in the system affecting flow and performance.