Industrial IoT Projects: The Complete Sensor-Selection Guide. For Free!


Sensor selection in IIoT projects is critical to ensure success, reliability, and efficiency. Read to explore Real-world examples and expert insights to make informed decisions in your industrial automation journey.

In today’s increasingly connected world, sensors play a crucial role in powering the Internet of Things (IoT), Industrial IoT (IIoT), Industrial Automation, and Industry 4.0 projects. As the backbone of these cutting-edge technologies, sensors help gather critical data from various environments and eventually enable businesses to optimize processes, reduce costs, and enhance efficiency. With over 75 billion IoT devices projected to be in use by 2025, the importance of sensors cannot be overstated. 

Read More: IoT, IIoT, Industry 4.0, and Industrial Automation: Myths, Similarities & Differences

However, selecting the right sensors, mounting them correctly, and ensuring seamless data transfer are vital steps in leveraging their full potential. Failure to follow best practices can lead to inaccurate data, compromised performance, and other detrimental effects. Sensor mishaps can be a real possibility if you are just starting to adopt IIoT technologies or expanding the scale of automation in your business. A classic example of costly failure due to sensors is the Mars Climate Orbiter (MCO) project, where a team from Lockheed Martin, which built the MCO, had programmed the spacecraft’s thruster sensor output acceleration data in English units (pound-seconds) instead of the metric units (newton-seconds), resulting in a sensor data inconsistency. The $327.6 million mission ended in failure.

Therefore, selecting appropriate sensors and maintaining data consistency are critical factors for the success of any Automation or IIoT project. In this comprehensive guide, we will explore essential strategies, tips, and criteria for maximizing sensor performance in your IIoT projects, with real-world examples and case studies, helping you unlock the true potential of Automation.

Upon completing this article, you will be able to:
  • Understand the significance of sensors in Industrial IoT projects
  • Identify key factors when selecting the right sensors (proven 13-point selection criteria).
  • How to compare various sensor types and technologies (with real-world examples).
  • Avoid common pitfalls and costly mistakes leading to inaccurate data or project failures.

Selection Criteria for Industrial IoT Sensors: 

Every Automation project demands a specific application of technology to solve a problem or enhance the existing system’s capabilities. Since every automation project is unique, sensors should also be selected specifically for the application. Typically, from the Project engineer’s perspective, the sensor should be capable of delivering the accuracy or sensitivity demands of the project, it should be rigid enough to withstand the surrounding environment, and has inbuilt Ingress protection, comply with data transmission protocols and regulatory bodies such as ATEX or PESO, etc. 

Though it is difficult to evaluate and present all the possible types of sensors according to their functional types, we are presenting a 13-point selection criteria that is succinct and act as a checklist for you while selecting sensors.

#A. Understanding the project/application requirements:

  1. Certifications and Industry-specific requirements: Assess the unique demands of your industry, such as the hazardous environments or specific regulations governing sensor usage. Since Sensors are Electro-Mechanical devices, the possible heat and spark generation risk should not be overlooked. Therefore, several industries, such as off-shore, marine, and oil & gas, have regulations to strictly use IECEx / ATEX / PESO or explosion-proof sensors on their platforms. Similarly, manufacturing, energy, agriculture, and logistics, may have distinct sensor requirements such as ISO 9001 quality compliance. A comprehensive list of sensor certifications for your industry can be found here: Sensor certifications.
  2. Surrounding and Environmental factors: Consider the operating conditions in which the sensors will be deployed and if the surroundings be harsh for the sensor to withstand.  Factors such as temperature, humidity, external pressure on the sensor, and exposure to chemicals or contaminants should be checked. These factors can impact sensor performance and durability. Select sensors that can withstand these conditions while maintaining accuracy and longevity. IP (Ingress Protection) is one such indicator of resistance to humidity and dust. Operating temperature and pressure limits will be shared by the Sensor OEM (or can be found on the specification sheet or datasheet).
  3. Energy (AC / DC Powered) and Voltage requirements: Majority of sensors are DC powered (12/24 VDC) power-consuming sensors, MPUs (magnetic powered units), and sensors powered on AC are an exception. Therefore while designing an IIoT solution, an energy balance with the existing systems should be considered not to load the grid supply. 
  4. Data accuracy, Range, and sensitivity: Before selecting a sensor, determine the required measurement range, level of data accuracy, and sensitivity for your application. High-precision sensors are often costly and may be required for critical processes, while lower-cost sensors with moderate accuracy could be sufficient for less critical applications. Similarly, ensure that chosen sensors meet the required measurement range and sensitivity.

Read More: Why Industries need to Quickly Adopt Automation?

#B. Types of sensors commonly used in IIoT:

Six (6) sensors are often used in the Industry to monitor and automate parameter measurement: 

  • Temperature sensors: These sensors measure temperature changes in various industrial processes. Examples include thermocouples, resistance temperature detectors (RTDs), and thermistors.
  • Pressure sensors: Pressure sensors detect changes in fluid or gas pressure, commonly used in industrial applications such as hydraulic systems, water management, and gas flow monitoring. Examples include piezoelectric, capacitive, and strain gauge pressure sensors.
  • Humidity sensors: Humidity sensors measure the amount of moisture in the air or a specific environment. These sensors are essential in agriculture, food processing, and pharmaceuticals, where maintaining proper humidity levels is crucial. Examples include capacitive, resistive, and thermal conductivity humidity sensors.
  • Flow sensors: Flow sensors measure the flow rate of fluids or gases in pipes and other channels. These sensors are widely used in water management, chemical processing, and HVAC systems. Examples include ultrasonic, electromagnetic, and vortex flow sensors.
  • Level sensors: These sensors detect and measure the level of liquids, solids, or granular substances in containers, tanks, or other storage systems. They are used in Oil & gas, water & wastewater treatment, chemical, pharma, FMCG, beverages, and energy industries to measure the level of fluids. Examples include float level sensors, Ultrasonic level sensors, Capacitive level sensors, Radar level sensors, and Optical and Hydrostatic types.
  • Proximity sensors: Proximity sensors detect the presence or absence of objects without physical contact. They are commonly used in manufacturing, robotics, and automation for object detection, positioning, and collision avoidance tasks. Examples include Hall effect sensors, MPUs, and sensors working on inductive, capacitive, and ultrasonic-based proximity measurements.

Read More: IoT, IIoT, Industry 4.0, and Industrial Automation: Myths, Similarities & Differences

#C. Comparing different sensor technologies

Note that each of the Six (6) sensors can further be divided into several types based on the principle of measurement, i.e., the technology used by the sensing device to measure a certain parameter. The selection criteria for sensor technology should be as follows: 

  1. Measuring media: Depending on the properties of the media being measured, an appropriate sensor technology can be chosen for a given application. For instance, in fluid sensing projects where the fluid doesn’t damage the sensor or interfere with its measurements, an in-contact sensor can be used, such as a float sensor for level measurement. Conversely, when dealing with fluid media that require contactless measurement, like concentrated acids, a contactless level sensor, such as an ultrasonic sensor, should be selected. This approach can be applied to other parameters as well, ensuring that the sensing technology is suitable for the specific characteristics of the media being measured.
  2. Evaluate the pros and cons of each technology: Evaluate the benefits and drawbacks of various sensor technologies to determine the best fit for your application. Consider factors such as response time, repeatability, sensitivity, and long-term stability.
  3. Cost considerations: Compare the costs of different sensor types and technologies, taking into account not only the initial purchase price but also the total cost of ownership, which includes maintenance, calibration, and replacement costs.

To facilitate the comparison of different technologies, we have examined two oil condition monitoring sensor brands – IHI (TF Detector) and Poseidon (Trident). Though both sensors monitor Solid contamination and oil quality in real-time, they operate on different technologies. By considering your specific application requirements, you can select the most suitable option between the two:

Oil Particulate Contamination - Sensor Technology
TF-Detector (IHI Make) TF Detector (IHI Make) Oil Particle content Sensor Comparison
Trident DM 450 (Poseidon Make) Trident DM 4500 (Poseidon Make) Oil Ferrous Contamintion Sensor Comparison
Principle of operation
Detection of magnetism within a sample
Propriteory technology
Detection modes
Ferrous content
Ferrous and Non-ferrous content
Reading display
Percentage (%) of Fe content
PPM, Microgram / Liter of contaminant
Range and sensitivity
Upto 2.0% ( ±0.002% or 2 PPM resolution)
1 PPM
Dimensions and weight
L - 178mm, W - 212mm, H - 106 mm
L - 153mm, W - 103mm, H - 76 mm, 0.68 kg
Max. Viscosity
Suitable for all lube and grease oils
Suitable for all lube and grease oils
Online / Offline
Online, contact monitoring
Online, contact monitoring
Power consumption and supply
Approx. 50W consumption, 100AC to 220V (50Hz or 60H)
Approx. 300 mA consumption, 10-30 VDC
Max. Flow rate
NA
0.95 to 38 LPM
Max. Pressure
3 Bar (For Flange Type) 5 Bar (For Passage Type)
10.3 Bar
Max. Temperature (limits)
Max. 70℃
-40 to 85 ̊C
Max. Viscosity
Viscosity independent
Viscosity independent
Ingress protection (IP Rating)
NA
IP65
Applicable to the type of oil
Grease and all lube oils
Grease and all lube oils
Display interface
Output from the sensor to be configured external, third party logger/software
Output from the sensor is configured to Poseidon Live software (no local display)
Parameters that are detectable
Ferrous content in PPM
1. PPM of Ferrous (>40 Micron) and Non ferrous particles (>150 Micron) 2. Particle type/size and approximate mass (cumulative mass, etc.) 3. Particle counts
Real-time and remote monitoring
Real-time and cloud monitoring (to be configured externally)
Real-time and cloud monitoring (to be configured externally)
Type of outputs from the sensor
Analog: 4-20mA
Digital: RS485/RS232 Modbus RTU, Pulse Output
Cost comparison
End User price - 7,50,000 INR*
End User price - 2,35,000 INR*

#D. Other Key factors to consider when selecting sensors

  1. Compatibility with existing infrastructure: Ensure the chosen sensors can be easily integrated into your existing systems and networks. Compatibility issues may lead to increased costs and complexities in the implementation process. 
  2. Ease of integration and scalability: Select sensors that are easy to install, configure, and maintain, allowing seamless integration into your IIoT infrastructure. You can consider selecting sensors that have the same digital (RS 485, ModBus, etc.) or analog output (4-20 mA or 0-12 VAC) protocol. This can offer scalability, enabling your system to grow and adapt to changing requirements.
  3. Power consumption and battery life: Consider the power requirements of the sensors, particularly for battery-powered or energy-harvesting applications. Certain industries are restricted to either a DC or AC power source. In such instances, additional SMPS or like devices may be required to convert power. Prioritize choosing sensors with low power consumption and long battery life to reduce maintenance and replacement costs.
  4. Data security and privacy: Ensure that the sensors and their associated communication protocols offer robust data security and privacy measures. This is particularly important for industries dealing with sensitive or confidential information, where data breaches can have severe consequences.
  5. Local Norms and Regulatory authority compliance: Certain regions, such as in Europe, insist that the products comply with the local European health, safety, and environmental protection standards (CE Certifications). Often this is not a quality indicator or a certification mark but regulatory compliance, and are assessed to meet safety, health, and environmental protection requirements.
  6. Calibration intervals: Sensors needing frequent calibration may cause hindrance and loss of data, so select the sensor technology that offers longer calibration intervals.

Read More: Why Industries need to Quickly Adopt Automation?

Summary and Next Steps: 

In summary, we have discussed the importance of sensors in IIoT projects and delved into the selection process by examining various sensor types, and their technologies.

Selecting the right sensors, mounting them properly, and facilitating seamless data transfer are crucial for the success of any IIoT project. These factors directly impact the system’s efficiency, reliability, and accuracy, enabling businesses to optimize their operations, reduce costs, and improve overall performance.

As technology continues to advance and the IoT landscape evolves, it is essential for professionals to stay updated on the latest developments and best practices. We encourage readers to explore additional resources on our Industry Digits website and consult us when necessary to ensure the successful implementation of your IIoT projects. 

We hope you found this guide on sensors in IIoT projects valuable. If you believe it could benefit others in your network, please feel free to share it with your colleagues and friends or on social media platforms. Sharing knowledge helps the entire community grow and stay informed.

-Lokesh Chennuru, for Industry Digits

To stay up-to-date with the latest trends and best practices in the world of IIoT, consider signing up for our newsletter or following us on social media. We regularly share informative articles, industry news, and expert insights to help you stay ahead in this rapidly evolving field. By staying connected, you’ll have access to a wealth of resources and knowledge that can help you make the most of your IIoT projects.


Lokesh Chennuru

6+ years of experience developing IoT and Industry 4.0 solutions, Lokesh is a recognized expert in Industrial Automation. He is pioneering the applications of Solar power and Low-cost biogas as alternative fuels. A ISO Certified Lead Auditor, who loves sharing his insights on Automation, current trends, and changes in industrial economics.

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