Humidity measurement at very high moisture environment?
Today, the humidity sensor is a product that is an important part of almost all automation applications, from our living spaces to production, produced by hundreds of companies. It will be customary that almost all humidity sensor documents specify 0-100%RH as the measuring range. This naturally causes errors in product selection in many applications. Writing 0-100%RH on a humidity sensor does not mean that it can measure 95%RH or 5%RH in the low zone. Although it is written 0-100%RH for the humidity measurement range in products or standard humidity sensors that have not specifically stated that they can measure in these regions, it is actually in the range of 20-80%RH.
First, let's take a look at the problems we encountered.
Problem 1 : Suitability to work in High Humidity
If your application is high humidity values (for example, over 80% RH), it should be well questioned whether the normal humidity sensors you will buy can work at these values. Even many moisture sensor vendors are unaware of this.
Problem 2: Accuracy selection
Another criterion to be considered in High Humidity applications is the measurement accuracy. The sensitivity data of all humidity sensors in the catalogs are for 25 ºC temperature and 50 %rH humidity values. Even for these conditions, if a non-sensitive humidity sensor is selected, this sensitivity will change very seriously according to the catalog data in high humidity and different temperature values. If the sensor is not special for high humidity applications and its sensitivity is not good, it is almost impossible to get efficiency at high humidity values.
Two measurement methods are ideal for High Humidity applications. The first is the psychrometry measurement method. Psychrometry method, which is a method calculated from wet and dry thermometer temperature differences, has remained at a very low level due to the difficulty of availability of measuring instruments or transmitters, and the need for periodic maintenance. The method, which is the most ideal for high humidity measurements, has a normal humidity sensor design, is practical to use and is maintenance-free; Electrolytic measurement management. This method, developed by a Swiss company about 50 years ago, can measure smoothly even at 99.9% RH humidity values and output to your automation system or you can use it portable.
In standard humidity sensors, when the humidity value reaches 95% RH, the condensation on the surface turns into water and covers the sensor surface completely. It gives you the humidity information that is around 90%RH as 100%RH as an incorrect humidity value and continues to show 100%RH for a long time even if the ambient humidity comes to lower levels.
This is not the case with the electrolitic sensor. You can accurately measure 99.9%. In addition, the sensitivity value is very high compared to the sensors on the market, and the response time to change is less than 1 second.
You can find a sample humidity sensor with Electrolitic Sensor, which works smoothly and sensitively in high humidity, from the XXX link.