How big is the error of electronic humidity drying box?

It is not accurate to tell you that the hygrometer is measured in a vacuum drying oven. We often say that there are two kinds of humidity, absolute humidity and relative humidity. The hanging hygrometer you bought belongs to the relative hygrometer. Relative humidity is generally only suitable for normal pressure environment. Relative humidity means that the hygrometer converts the water-vapor ratio under normal pressure at this temperature through temperature, and the relative humidity is affected by temperature, pressure and water vapor content. However, the conventional relative hygrometer only inputs the temperature, so it cannot measure the humidity in vacuum environment. If you need to measure humidity, you need to buy a professional absolute humidity meter. This kind of hygrometer must be able to collect three parameters: ambient temperature, ambient water vapor humidity and pressure, and then you can calculate them through the humidity calculation formula. If accurate humidity is needed in industrial production, the formula must be input into PLC, and then the humidity in the box is converted by PLC. Generally speaking, if your humidity requirements are not very precise, ordinary measurements can be used as a reference, so don't worry too much.