Industrial safety sensors are critical for ensuring the safety and protection of workers, machinery and the overall production process in various industries. They use a combination of different technologies to monitor conditions and detect hazards.
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Proximity sensors
These sensors comprise inductive, capacitive, ultrasonic and laser technologies and are used to detect the presence or absence of an object without physical contact. Inductive sensors work with metal objects; capacitive sensors detect a wide range of materials; and ultrasonic and laser sensors can detect the distance to objects. Applications include machine safeguarding, positioning and motion detection.
Pressure sensors
Typically, industrial pressure sensors have been centered around piezoelectric technology, which shows optimal linearity, accuracy and stability. Following this, capacitive, strain gauge and optical pressure sensors form the balance. Their function is to monitor pressure levels in systems such as pressure vessels, piping systems, hydraulic circuits, pneumatic equipment or tanks. They ensure that pressure levels are within safe operating limits. Applications include gas and liquid pressure monitoring, pipeline safety and tank level monitoring.
Temperature sensors
In industrial applications, thermocouples, such as types K or J, are commonly used. The highest temperature thermocouples are Type C, which are made from tungsten rhenium alloys, and type B, R or S, which are platinum rhodium alloys, with capabilities in the 1,000 °C to 2,315 °C temperature range.
For high-accuracy temperature measurements below 400 °C, resistance temperature detectors (RTDs), typically Pt100 (100 Ω at 0 °C) and Pt1000 (1,000 Ω at 0 °C) are the most commonly used, the latter having 10 times the resolution of the former.
Thermistors and infrared sensors are additional alternatives. The very latest temperature-related sensors are known as thermochromic; in these products, a color change based on temperature ranges provide 24/7 safety monitoring to give a predictive warning on overheated equipment. The permanent quality of the change highlights issues in straight and non-continuous load applications, protecting against electrical fire or equipment failure.
All these are used to measure temperature in machines, equipment and processes. Overheating is a significant safety risk, so these sensors help prevent damage and hazards. Typical applications include over-temperature protection in machines, processes, motors and electrical systems.
Gas and chemical sensors
These safety sensors comprise electrochemical, catalytic, infrared (IR) and metal oxide semiconductor (MOS) technologies to detect hazardous gases like carbon monoxide (CO), methane (CH4), hydrogen sulphide (H2S), oxygen (O2), and toxic chemical vapors. They are essential for ensuring a safe working environment, especially in confined spaces. Their applications include leak detection, air quality monitoring and toxic gas detection in industrial plants, oil rigs and mining.
Smoke and fire sensors
In this application, ionization, photoelectric, thermistor-based and infrared technologies are used to detect smoke particles, heat and flames to prevent fire hazards. Applications include fire detection in manufacturing facilities, warehouses and high-risk environments.
Vibration sensors
Vibration sensors can be traced back to the 1920s and comprise piezoelectric, accelerometers and strain gauge technologies. In the 1960s, tunable analog filters were added to meters so that users could discriminate between frequencies. Around this same time, fast Fourier transform (FFT) vibration detection and analysis started increasing. Fast Fourier transform is an algorithm for transforming a time-domain signal into a frequency-domain signal. These systems measure vibrations or oscillations in machinery. Excessive vibration can indicate malfunction or risk of failure. Their applications include vibration monitoring for rotating equipment like motors, pumps and turbines.
Sensors and the predictive analytics lead to the IIoT-enhanced, prescriptive maintenance future, a future in which software will inform maintenance teams on when, where and why to complete maintenance. They provide advanced safety warnings.
Motion sensors
There are three types of motion sensors that are used frequently. The function of passive infrared (PIR), microwave and dual tech/hybrid—ultrasonic, microwave and radar—is to detect motion of objects or people in the environment. These sensors can trigger alarms, stop machinery or activate safety features. Typical applications include safety light curtains, machine guarding, intrusion detection and employee safety monitoring.
Safety light curtains and grids
Infrared light beams are applied where a barrier of light beams is created across a defined area. If a person or object crosses the light curtain, the system triggers a safety shutdown or alert. Typical safety applications include machine safeguarding, robot protection and access control to hazardous zones.
Optical sensors
Typical optical sensors comprise photoelectric, laser and optical reflection devices and are used to detect the presence of objects or humans based on light interference or reflections. They can measure distance or detect motion. They are used as safety barriers, conveyor system monitoring and machine operation control.
Radar and lidar sensors
These make use of radio waves and light waves. Their function is the application of radar or laser signals to detect objects, measure distances and avoid collisions. Lidar is often used for precise location mapping. They are typically used for automated vehicle safety, navigation in warehouses and collision avoidance in industrial robots.
Safety relays and controllers
These items comprise smart relays, electronic control and programmable logic controllers (PLCs), and their function is to integrate signals from various safety sensors and control safety mechanisms, like stopping machinery or activating alarms when unsafe conditions are detected. They are widely used in machine control systems, emergency shutdown systems, and safety interlocks.
Wearable safety sensors
These make use of the latest technology and are comprised of radio frequency identification (RFID), Bluetooth, accelerometers, global positioning system (GPS) and electrochemical sensors. Their function is to monitor the health and safety of workers by tracking location, detecting dangerous gases and monitoring environmental conditions. They’re typically worn by workers in in hazardous environments for mining, oil rigs and construction sites.
Load and force sensors
This technology comprises strain gauges, piezoelectric and capacitive sensors, which are used to measure the force, load or weight applied to a machine or structure, ensuring it remains within safe operational limits. When applied to load monitoring in cranes, lifting systems and mechanical equipment, they provide the necessary safety guarantees.
Machine vision systems
These systems include cameras, image processing and artificial intelligence (AI) algorithms, and they monitor and detect hazards in real time, such as detecting if an operator is too close to a dangerous machine. Industrial applications include visual inspection, hazardous zone detection and operator safety.
Environmental sensors
We employ safety sensors to protect workers and others from the environment. In these applications, humidity, temperature and particulate-matter sensors detect changes in environmental conditions that may pose a risk to both people and machinery, such as extreme humidity or temperature levels. In terms of applications, ensuring safety in environments such as clean rooms, data centers and chemical processing plants are commonly found.
These technologies often work together to provide comprehensive safety solutions in industrial settings, offering early warnings, preventing accidents and minimizing damage to personnel and equipment.
