How do you evaluate and compare different sensor vendors and products for industrial control projects?

1 Sensor types

Industrial control relies on a variety of sensors to measure physical and chemical properties. Common examples include temperature sensors like thermocouples, RTDs, and thermistors; pressure sensors such as piezoresistive, capacitive, and strain gauge variants; flow sensors like differential pressure, turbine, and ultrasonic types; level sensors like capacitive, ultrasonic, and optical models; proximity sensors such as inductive, capacitive, and magnetic types; and position sensors such as potentiometers, encoders, and hall effect variants. Each of these can provide valuable insights into the environment they are monitoring.

2 Sensor applications

Sensors are applicable in industrial control for various purposes, depending on the process or machine that needs to be monitored or controlled. Temperature sensors, for instance, can be used to regulate the heating or cooling of a substance or device, such as a furnace or boiler. Pressure sensors can detect the pressure level of a fluid or gas in a pipe or vessel, like a pump or valve. Flow sensors measure the flow rate or volume of a fluid or gas in a pipe or channel, such as a water supply or gas distribution. Level sensors measure the level of a fluid or solid in a tank or vessel, like a fuel storage or water reservoir. Proximity sensors detect the presence or absence of an object near a sensor, such as on a conveyor belt, sorting machine, or metal detector. Lastly, position sensors measure the position of a shaft or rod in linear or rotary motion, like on a servo motor, stepper motor, or solenoid.

3 Sensor evaluation

When selecting a sensor for an industrial control project, there are several factors to consider that can affect its performance and suitability. These include accuracy, resolution, range, response time, linearity, stability, reliability, and durability. Accuracy refers to the degree to which the sensor output matches the true value of the measured property. Resolution is the smallest change in the measured property that the sensor can detect. Range is the minimum and maximum values of the measured property that the sensor can handle. Response time is the time it takes for the sensor to react to a change in the measured property. Linearity is the extent to which the sensor output is proportional to the measured property. Stability is the ability of the sensor to maintain its accuracy and resolution over time and under varying conditions. Reliability is the probability of the sensor to function properly and without failure. Finally, durability is the resistance of the sensor to physical or environmental damage.

4 Sensor comparison

When selecting a sensor vendor and product, you should consider several aspects that affect the quality and cost of the sensor. These include specifications such as accuracy, resolution, range, response time, linearity, stability, reliability, and durability; standards compliance like ISO, ANSI, IEC, UL, CE, or CSA; certification from an independent or authorized body like NIST, TUV, SGS, or BV; warranty provided by the vendor to repair or replace the sensor in case of defect or failure; support offered by the vendor in terms of technical assistance, training, maintenance, or troubleshooting; as well as the price of the sensor including any discounts, fees, taxes, or shipping costs.

5 Sensor selection

Choosing a sensor for an industrial control project requires defining your measurement objectives and criteria, comparing your options and alternatives, and testing and validating your choice. You should consider factors such as accuracy, precision, speed, stability, reliability, durability, environmental conditions, specifications, standards, certification, warranty, support, and price. Additionally, it is important to verify that the sensor works as expected and meets your criteria by calibrating and adjusting the sensor to optimize its performance. Finally, you must monitor and evaluate the sensor output and feedback. By following these steps you can select the sensor that best meets your requirements and budget.