It is an electronic device that measures the humidity in its environment and converts its findings into a corresponding electrical signal. Humidity measurement determines the amount of water vapor present in a gas that can be a mixture, such as air, a pure gas, such as nitrogen. The most commonly used units for humidity measurement is relative humidity function of temperature, dew or frost point function of pressure and parts per million absolute measurements.
In relative humidity the ratio of the partial pressure of water vapor present in a gas to the saturation vapor pressure of the gas to the saturation vapor pressure of the gas at a given temperature.
In dew point the temperature above 0 C at which the water vapor in a gas condenses to liquid water.
In frost point the temperature below 0 C at which the vapor condenses to ice.
Application of humidity sensor
- Industrial process control systems. Storage and warehouses
- Climate control for greenhouses
- Meteorological applications
- Office automation, room comfort control
- Automotive cabin air control
- Home appliances, air conditioners
- Food processing
- Medical applications
- Chicken coops, pig barns
Advantages of humidity sensor
Capacitive
- It does not require any maintenance for longer period
- Flexible to use
- Atmospheric pressure is independent
Psychometric
- Higher accuracy
- Higher quality
- It is usable without any issue
Hygrometric
- It is easy to clean
- It is simple in construction
- It is lower in cost
Disadvantage of humidity sensor
Capacitive
- It has limited long term stability.
- It is sensitive to certain aggressive substances.
Psychometric
- It is difficult to use below the temperature of 0℃ and with lower humidity.
- Long term measurement is limited due to required water reserve and
- Wick maintenance.
Hygrometric
- It has limited accuracy.
- It has a limited measurement range.
- It is slow in measurement.