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Humidity sensors perform different functions like sensing, measuring, and reporting air temperature and moisture content. These devices also have several industrial applications. They are used in diverse industries like HVAC, automotive, food production, and medical industries. The device is used in every industry that needs a controlled atmosphere.
Several aspects need to be focused on while buying a reliable humidity sensing device. This post has shared a guide to help choose the best humidity monitors for your application.
Know the Different Types of Humidity Sensing Devices
Table of Contents
There are two main types of humidity sensors – resistive and thermal conductivity humidity sensing devices. Both have different ways of measuring humidity.
Resistive Humidity Sensing System
The resistive humidity sensing device measures electrical change brought out by conductive substance. These devices use the combination of AC excitation voltage and electrode to measure relative humidity.
Thermal Conductivity Humidity Sensing System
On the other hand, the thermal conductivity humidity system measures absolute humidity. They calculate the difference in air conductivity. For example, it measures the conductivity of dry air and air containing water vapour. After obtaining measurements, it compares values. These systems have thermistor elements to create a bridge circuit for measuring resistance difference.
Factors to consider while selecting the humidity sensing system
Accuracy
Before you judge the sensor for its accuracy, you need to learn the right definition of accuracy in terms of the humidity sensing system. The accuracy refers to the agreement’s closeness between two values – true quantity value and measured quantity value.
The accuracy does not consider the long-term drift of the unit or uncertainty (due to the wrong calibration) related to the reference device. The calibration of the sensor is established on a 9-point system. In general, the higher the humidity sensing system’s price, the more accurate it will be.
Interchangeability
The interchangeability refers to the range of voltages for any humidity sensors at RH points over a specific humidity range. The interchangeability increases with increasing RH. The RHIC-die is cut only at 0% RH. Cutting the die at other values is not advisable. The interchangeability can increase the cost of a humidity sensing system that can raise the vibration. This automatically increases calibration costs.
Condensation
When the sensor gets wet, it gives 100% humidity output. When the water evaporates, the readings don’t return to normal due to the residue. The water that condenses is not always pure and leaves a residue that may affect the sensor’s accuracy. If the environment has condensation, you also need to consider the cost of purchasing condensation filters.
Power
Power consumption is a vital element in the choice of humidity sensing systems. These sensors are working all the time, consuming energy. The average current consumed by sensors is 9μA, and the ratio of energy is 6.8%. The ratio of energy refers to describing system energy output versus system energy input.
Thus, you can see selecting the right humidity sensing device is not easy, and you need to consider several factors. Besides that, you also need to choose the right company which makes these devices.
