A weighting dryer is a laboratory measurement device designed for determining the relative humidity of small samples of different materials.
The weighting dryer consists of two parts – a precise scale and connected to it a drying chamber with two heating halogen lamps. The drying temperature (set by a user) is regulated by a set of automatic regulation. Additionally the weighting dryer can be equipped with a thermometer, which can be used for:
Three types of weighting dryers are offered with the technical parameters introduced below. Choosing a particular type depends on a type of work that is to be performed on a certain weighting dryer (only drying or precise weighing).
When specifying a sample humidity a real drying temperature plays an important role. Its value should closely respond to a set temperature. Another solution is a possibility of drying temperature correction through the correction coefficient.
The latest thing with the weighting dryers is an option enabling two level drying. The process of drying runs automatically for the first drying threshold and then it is switched over to drying in the second scope of temperature.
The weighting dryer is in standard equipped with an interface RS-232, which allows on cooperation with a printer KAFKA 1/Z or a PC computer. When drying the samples the weighting dryer currently sends out the humidity values calculated in the sampling time intervals through the connection RS-232. After finishing the measurements it is also possible to print out a report of drying. The computer programs POMIAR (DOS) and WAGWIN (WIN95) allow on watching a curve of drying (important for stating, whether the sampling is running smoothly), creating a report from the measurements and saving it on a computer disk as well as performing the statistical calculations.
The properties and usage of the weighting dryers were introduced in an additional description, which discusses the following:
|SCALE TYPE||WPS 30S||WPS 110S||WPS 210S|
|Max load [g]||30||110||210|
|Min load [mg]||20|
|Resolution of mass reading [mg]||1|
|Graduation legalisation [mg]||10|
|Humidity reading resolution [%]||0,01|
|Temperature reading resolution||1 °C|
|Scope of drying temperature||50 ... 160 °C (optionally up to 250°C)|
|Power of halogens||standard 2 x 200W (optionally 2 x 300W)|
|Sampling time||from 1 to 59 seconds|
|Maximum drying time set||9 hours 59 minutes|
|Digital displays||time of drying, mass (humidity), time of drying|
|Scope of environment temperature||from + 15°C do + 30°C|
|Output signal||RS 232|
|Scale pan diameter [mm]||100|