Industrial sensors are essential to modern automation. They help machines detect objects, measure conditions, monitor processes, and make decisions without constant human intervention.
But with so many different types of industrial sensors available, choosing the right one for an application can be challenging.
From detecting whether a part is present on a conveyor to measuring the temperature or pressure inside a process, each sensor type is designed for a specific purpose.
In this guide, we’ll explain 7 common types of industrial sensors, how they work, and when you would use each one.
What Is an Industrial Sensor?
An industrial sensor is a device that detects a physical condition or change in its environment and converts that information into a usable electrical signal.
Depending on the sensor, it may detect:
- The presence or absence of an object
- Distance
- Temperature
- Pressure
- Liquid or material level
- Position or movement
- Speed or rotation
Sensors communicate this information to other components in an automation system, such as a PLC, HMI, motor controller, or other control system.
For example, a sensor on a production line might detect when a part reaches a certain position. The sensor sends a signal to the PLC, which then tells another machine to perform the next step.
In simple terms:
Sensor → Detects something → Sends a signal → Control system responds
7 Common Types of Industrial Sensors
Proximity Sensors
What is a proximity sensor?
A proximity sensor detects the presence of an object without physically touching it.
Many proximity sensors use an electromagnetic field to detect metal objects. When a metal target enters the sensor’s detection range, the sensor changes its output signal.
Inductive proximity sensors are particularly common in industrial automation.
When would you use a proximity sensor?
Proximity sensors are often used when you need to detect:
- Metal parts
- Machine components
- Position of moving equipment
- End-of-travel positions
- Parts on an assembly line
- Rotating components
For example, a proximity sensor could detect when a metal component reaches the end of a conveyor. The sensor sends a signal to the PLC, allowing the machine to begin the next operation.
Advantages of proximity sensors
- No physical contact
- Reliable in demanding industrial environments
- Long operating life
- Good for high-speed applications
- Excellent for detecting metal objects
Keep in mind
Inductive proximity sensors are primarily designed to detect metal. If you need to detect non-metallic materials such as cardboard, plastic, glass, or wood, another type of sensor may be a better choice.
Photoelectric Sensors
What is a photoelectric sensor?
Photoelectric sensors use light to detect an object.
A photoelectric sensor sends out a beam of light and detects whether that light is interrupted or reflected by an object.
Depending on the application, photoelectric sensors can detect a wide range of materials and objects.
When would you use a photoelectric sensor?
Photoelectric sensors are commonly used for:
- Detecting products on conveyors
- Counting parts
- Detecting objects regardless of material
- Checking whether a product is present
- Detecting objects at a specific location
- Packaging and material handling applications
For example, a photoelectric sensor could be positioned alongside a conveyor. Every time a box passes through the sensor’s beam, the system registers that a box has arrived.
Ultrasonic Sensors
What is an ultrasonic sensor?
Ultrasonic sensors use sound waves to detect objects or measure distance.
The sensor sends out a high-frequency sound wave. When that sound wave hits an object, it reflects back toward the sensor.
The sensor measures the returning signal to determine the object’s distance.
When would you use an ultrasonic sensor?
Ultrasonic sensors can be useful when you need to detect:
- Objects regardless of color
- Transparent objects
- Liquids
- Material levels
- Distance
- Objects that are difficult to detect with light-based sensors
For example, an ultrasonic sensor could measure the level of liquid inside a tank without physically contacting the liquid.
Advantages of ultrasonic sensors
- Can detect many different materials
- Not dependent on object color
- Can measure distance
- Useful for liquids and bulk materials
- Non-contact measurement
Keep in mind
Environmental conditions can affect ultrasonic sensors. Temperature, airflow, foam, and certain materials can influence how sound waves travel or reflect.
Pressure Sensors
What is a pressure sensor?
Pressure sensors measure the force exerted by a gas or liquid within a system.
They convert pressure into an electrical signal that can be monitored by a control system.
Pressure sensors are commonly found in systems involving:
- Hydraulics
- Pneumatics
- Pumps
- Compressors
- Process equipment
- Water systems
- HVAC systems
When would you use a pressure sensor?
A pressure sensor may be used to:
- Monitor system pressure
- Detect pressure changes
- Protect equipment
- Control pumps or compressors
- Identify potential leaks or system problems
- Maintain a specific operating pressure
For example, a pressure sensor could monitor the pressure in a pneumatic system. If pressure drops below a specified level, the control system could trigger an alarm or activate another component.
Temperature Sensors
What is a temperature sensor?
Temperature sensors measure the temperature of a machine, process, material, or environment.
Two common technologies used in industrial applications are:
- RTDs
- Thermocouples
Temperature sensors can send information to a control system, display, recorder, or other monitoring equipment.
When would you use a temperature sensor?
Temperature sensors are commonly used to monitor:
- Motors
- Bearings
- Ovens
- Furnaces
- Tanks
- Process equipment
- Manufacturing processes
- HVAC systems
For example, a temperature sensor might monitor an industrial oven to ensure the process remains within a specific temperature range.
Why is temperature monitoring important?
Temperature changes can provide important information about equipment and processes.
Unexpectedly high temperatures may indicate:
- Overheating
- Excessive friction
- Electrical problems
- Cooling system issues
- Process problems
Monitoring temperature can therefore play an important role in equipment protection and predictive maintenance.
Level Sensors
What is a level sensor?
Level sensors detect or measure the amount of material inside a container, tank, hopper, or other vessel.
Depending on the technology, a level sensor may detect a simple high/low condition or continuously measure the level of material.
When would you use a level sensor?
Level sensors are frequently used to monitor:
- Water
- Chemicals
- Oils
- Fuel
- Wastewater
- Powders
- Granular materials
- Other bulk materials
For example, a level sensor could monitor a tank and alert the control system when the liquid reaches a predetermined level.
Why use a level sensor?
Level sensors can help prevent:
- Overflow
- Empty tanks
- Pump damage
- Production interruptions
- Material shortages
The best type of level sensor depends heavily on the material being measured and the environment in which the sensor will operate.
Magnetic Sensors
What is a magnetic sensor?
Magnetic sensors detect the presence, position, or movement of a magnetic field or magnetic target.
One common industrial application is position detection.
Magnetic sensors can be used with magnetic targets or magnets to determine whether a machine component is in a particular position.
When would you use a magnetic sensor?
Magnetic sensors are often used for:
- Cylinder position detection
- Machine position sensing
- Door or guard monitoring
- Position confirmation
- Industrial automation equipment
For example, a magnetic sensor mounted to a pneumatic cylinder can detect when the cylinder reaches a particular position.
Why use a magnetic sensor?
Magnetic sensing can provide a compact and reliable way to detect position, particularly when physical contact isn’t desirable.
How Do You Choose the Right Industrial Sensor?
Choosing the right sensor starts with understanding what you’re trying to detect and the environment where the sensor will operate.
Consider these questions:
What are you detecting?
Is it:
- Metal?
- Plastic?
- Liquid?
- A powder or granular material?
- Temperature?
- Pressure?
- Position?
- Distance?
How far away is the target?
Detection distance can significantly influence which sensor technology is appropriate.
Does the sensor need to make physical contact?
Most industrial sensors provide non-contact detection, but the appropriate technology depends on the application.
What environmental conditions will the sensor experience?
Consider:
- Dust
- Water
- Oil
- Chemicals
- Heat
- Cold
- Vibration
- Outdoor exposure
How far is the application?
High-speed manufacturing applications may require sensors capable of responding quickly and reliably as objects move through the detection area.
What type of output does your control system require?
Your sensor needs to communicate properly with the equipment receiving its signal, such as a PLC or other control system.
What are the installation requirements?
Consider the available space, mounting configuration, sensing distance, wiring, and connector requirements.
Industrial Sensors Are the Eyes and Ears of Automation
Sensors are a critical part of modern industrial automation. They allow machines and control systems to understand what’s happening in the physical world and respond accordingly.
Whether you’re detecting a metal component with a proximity sensor, counting products with a photoelectric sensor, measuring tank level with an ultrasonic sensor, or monitoring temperature and pressure, the right sensor can make an automation system more reliable and efficient.
The best sensor isn’t necessarily the most advanced or expensive option. It’s the one that reliably detects what you need, in the environment where you need it, and communicates effectively with the rest of your control system.
Need Help Choosing an Industrial Sensor?
Selecting the right sensor can depend on several factors, including the target material, sensing distance, environmental conditions, mounting requirements, and control system.
If you’re unsure which type of industrial sensor is right for your application, Lakeland Engineering Equipment Company can help you evaluate your requirements and find the right solution.