Pressure Sensors: The Design Engineer's Guide

Pressure sensors: 3 industrial applications enabling the smart factory

Real-time sensor data is enabling factories to better understand their own processes and keep them running. And putting that data into the IIoT also helps optimise how raw materials are ordered, handled and consumed. Knowing what to reorder and when can keep continuous processes at high capacity.

Smart manufacturing is changing the way we make, package and distribute just about everything, but Industry 4.0 is revolutionising the way our factories operate. While the Industrial IoT is dependent on connectivity, fundamentally it’s harnessing raw data and turning that into operational intelligence, which means sensors are key to the entire process. While there are many types of sensor at play here, the pressure sensor is probably the most diverse and widely deployed type of sensor in the IIoT.
 

1. Monitoring process flows

Differential pressure sensors are used extensively in process flows where a fluid needs to pass through some form of barrier, such as a filter. Under normal conditions the pressure difference between the upstream (often called the line or influent pressure) and the downstream (effluent) pressure should be nil or minimal. As the filter becomes blocked with contaminants, the downstream pressure will decrease, which causes the difference measured to increase.

The sensor’s output can be calibrated to show the maximum permissible pressure difference at full scale. For example, a 4-20mA output could be calibrated to show 20mA when the pressure difference reaches the maximum permissible, but read 4mA when the pressure difference is nil.

Differential pressure sensors measure the difference between the influent and effluent pressures of a filter, which should be nil under normal operating conditions but will rise as the filter becomes clogged. (Source: http://www.te.com/usa-en/products/sensors/pressure-sensors/pressure-transducers/differential-pressure-transducers-for-filtration.html 
 

2. Measuring safe levels in liquid tanks

Submersible pressure sensors that are certified for use in intrinsically safe areas can be used to measure liquid pressures of up to 30 PSI with either a voltage or current (4-20mA) output. Positioning a submersible pressure sensor at the bottom of a tank would provide an accurate reading of the contents of the tank, thereby alerting workers or the process control system when the level in the tank falls below an allowable lower limit.

The pressure at the bottom of a tank – normally called the hydrostatic or head pressure – is measured in units of distance (feet, inches, meters) of water columns. For example, 27.670 inches of water column (WC) is around the same as 1 PSI at 100°F.

The pressure measured is only dependent on the height of the tank (as opposed to its shape) or the volume of the liquid. For this reason it is important that the sensor is placed at the bottom of the tank (instead of half way down).

Process controllers can calculate the level of liquid in a tank by measuring the hydrostatic pressure, which is more accurately measured when the density of the liquid is also known.
 

3.Managing control loops

As well as being used to monitor processes, pressure sensors are often instrumental in the control loop. This is particularly relevant in the use of hydraulics, where pressurised fluids are used to apply effort in presses or lifts for example.

The sensors are often small, particularly those based on MEMS technology. They can measure less than 2mm on each side yet be capable of measuring absolute pressures in the region of 20 Bar or more. This makes them suitable in a range of applications, including medical and automotive.
 

Even smarter sensors

Smart factories are now employing smarter sensors, such as pressure sensors with built-in Bluetooth connectivity, allowing them to be monitored wirelessly. These sub-systems feature a gauge pressure sensor, Analog to Digital Converter and Bluetooth radio in a single sealed unit that can be mounted in places where adding wires may be difficult. As they are battery-powered they can operate autonomously for as much as two years without any maintenance, providing accurate pressure sensor readings for gases, liquids and even mildly corrosive fluids.

Pressure sensors are fundamental in the smart factory and in enabling Industry 4.0.

What else are pressure sensors used for?

Find out more in our articles on applications in automotive, building automation, consumer and wearables, medical and industrial applications.

Pressure sensors: 10 innovative automotive applications.

Pressure sensors: 8 life-saving medical applications.

Pressure sensors: 8 building automation applications.

Pressure sensors: 11 life-enhancing consumer applications.

Looking for more on pressure sensor technology? Check out the further chapters of this guide below, or if you're pressed for time you can download it in a PDF format here.

Need some advice on pressure sensors?

Our pressure sensor experts are on hand to help you make the right choice for your application.

Webinar

Discover the keys to designing pressure sensor applications with this 30-minute technical presentation and Q&A with Nicholas Argyle, Applications Engineer EMEA, TE Connectivity.

Watch On Demand

White paper

Need a more digestible introduction to pressure sensors? Download the white paper, 'Pressure sensors: Design considerations and technology options'.

Download

Sensor solutions brochure

Discover the latest sensor solutions available from Avnet Abacus.

Download

Sensors linecard

Explore our pan-European sensor suppliers and their products and solutions.

Learn More

New products

Discover the latest product announcements from our sensor suppliers.

Learn More

TE Connectivity MS5611-01BA03 Series Pressure Sensor Product Spotlight

Display portlet menu

TE Connectivity

MS5611-01BA03 series SS cap barometric pressure sensor

Learn more about TE Connectivity's MS5611 series barometric pressure sensor, optimised for altimeters and variometers with an altitude resolution of 10 cm.

TE Connectivity MS5611-01BA03 Series Pressure Sensor

Omron 2SMPB Barometric Sensors Product Spotlight

Display portlet menu

Omron

2SMPB barometric pressure sensors

2SMPB-02B and 2SMPB-02E sensors provide stable, reliable height and pressure measurements for changes in elevation of as little as 2m, making them ideal for drones, car navigation and altitude meters.

Omron release two new Barometric Sensors for battery operated mobile devices.

Pressure Sensors Chapter 1 GBL

Display portlet menu

Chapter 1

How pressure sensors work

An introduction to pressure sensors covering the different types, how they work, their function, construction, and what to consider in your design choices.

Pressure sensors chapter 1 graphic

Pressure sensors chapter 6 GBL

Display portlet menu

Chapter 6

The core pressure sensor technologies

What’s the difference between the different pressure sensor technologies? And how do you know which one to use?

Pressure sensor guide chapter 6 graphic

Pressure Sensors Chapter 3 GBL

Display portlet menu

Chapter 3

The different types of pressure sensors

Discover how pressure sensors vary according to the type of pressure measurement, sensing principles, output signal, media, MEMS technology, mounting and more.

Pressure sensor guide chapter 3 graphic

Pressure sensors chapter 7 GBL

Display portlet menu

Chapter 7

Pressure sensors for different media types

An in-depth guide to pressure sensors for different media types. Learn about the technology, applications, different options, their specifications and their limitations.

Pressure sensor guide chapter 7 graphic

Pressure sensors chapter 4 GBL

Display portlet menu

Chapter 4

Pressure sensor output signals

Sensors, transducers, or transmitters? The right selection is important for your application. So what's the difference and how do you choose between them?

Pressure sensor guide chapter 4 graphic

Pressure sensors chapter 8 GBL

Display portlet menu

Chapter 8

Pressure sensing in harsh environments

An in-depth guide to pressure sensors for harsh environments - designing for extreme temperatures, high pressure, and corrosive and dynamic environments.

Pressure sensor guide chapter 8 graphic

Pressure sensors chapter 5 GBL

Display portlet menu

Chapter 5

Types of pressure measurement

What’s the difference between absolute, gauge and differential pressure sensors? And how do you know which one to use?

Pressure sensors guide chapter 5 graphic

Pressure sensors chapter 9 GBL

Display portlet menu

Chapter 9

Understanding specifications

Explore the datasheet and the different factors affecting the accuracy of pressure sensor readings. Discover how to make the right choice for your application.

Pressure sensor guide chapter 9 graphic