What is overpressure and how to prevent it?

What is rated pressure, overpressure, burst pressure?

In many applications and industries, it is not uncommon to come across the risk of excessive pressure, or overpressure, within the pneumatic or hydraulic network of equipment, especially in facilities with a high degree of automation. If this phenomenon is not controlled properly, it may cause permanent damage to equipment and production lines. That is why pressure sensors are commonly used as some form of protection, in several operations, such as industrial, medical, bioprocessing, and pharmaceutical.

Nevertheless, pressure transducers, since they are designed to measure specific pressure ranges (e.g. 0 barg to 100barg), are not always able to handle extreme levels of pressure. In order to handle that, engineers and designers have defined pressure ratings that can describe the conditions that a pressure component can withstand without affecting its operational performance. These are divided to:

• rated pressure,
• overpressure
• and burst pressure.

The maximum pressure that the manufacturer assigns as the desired pressure at which a device will function properly is normally outlined as rated pressure. An overpressure value is a condition where the pressure transducer can withstand the excessive pressure without affecting performance or compromising subsequent measurements. Under different situations, overpressure is mistaken for burst pressure, which is defined as the maximum pressure that can be applied without physically damaging the body of the sensing component.

For example, if a pressure sensor has 2bar rated pressure, 5x overpressure and 10x burst pressure, this means that the sensor can measure pressures up to 2 bar, it can withstand overpressures up to 10bar without being damaged and if the pressure reaches 20bar the sensor sealing will burst. From 10 to 20bar, the sensor does not burst but it is damaged and will not operate as expected.

What can cause Overpressure?

Different factors can trigger overpressure, including unintentionally increased heat, uplift, a faulty pressure regulator, process synchronization, or an amalgamation of all these. These causes are common in compartments of industrial applications, such as solenoids, centrifugal pumps, regulators, and valves.

How to prevent catastrophic failures due to Overpressure?

As explained above, overpressure is an inevitable phenomenon in any production, process and industry. Even a small overpressure event (in the range of milliseconds) can damage the installed pressure sensors and equipment permanently. The best solution to prevent the overpressure event from damaging the critical equipment is to handle the problem at its root. This can be done by selecting a suitable pressure sensor that can handle the maximum possible overpressure. This is where MEMS capacitive pressure sensors can really make a difference.

Due to their design and measurement principle, MEMS capacitive pressure sensors can handle up to 100x overpressure making them the only available sensor technology in the market that can withstand such high overpressures.

The overpressure tolerance along with the excellent accuracy and total error band specifications, make MEMS capacitive pressure sensors ideal for any application that uses pumps or valves, especially in automation equipment, where overpressure is mostly experienced. In such applications, conventional pressure sensors could be affected and should be avoided.

Before selecting a sensor, the maximum pressure value for the application needed should be taken into consideration. Understanding the advantages of each technology, the dynamics of their system, the limits of the sensor, and the various ways it can be applied is important, to have increased productivity and lower maintenance costs.

In the following figure, you can see an application example of the overpressure performance of a 10bar absolute calibrated sensor. The sensor’s Maximum Expected Operating Pressure (MEOP) is 10 bar. The sensor is measured at a reference pressure of 9.3 bar abs and then pressurized at the following pressure steps as indicated below.

As it can be seen from the figure above, the sensor returns to nominal performance even when 100x overpressure is applied for a long period of time.

Pressure sensors with high overpressure tolerance

ES Systems has developed high-end pressure sensors with cutting-edge MEMS capacitive technology and overpressure tolerance. Because of their revolutionary design, they can withstand up 100x the rated pressure with no plastic deformation and can be applied in any harsh environmental condition. This exceptional category includes:

• ESCP-MIS1 – a capacitive pressure sensor that can provide exceptional accuracy with great repeatability and stability in demanding environments.
• ESCP-BMS1 – a silicon capacitive pressure sensor, with high overpressure tolerance, flawless and perfect for applications that require high accuracy and low total error band, such as industrial, medical, and HVAC
• ESCP-MIT1 – a heavy-duty pressure transmitter, ideal for industries looking for results with advanced accuracy and resolution.