The mass difference in the filter membrane before and after the test is used to determine the mass of contaminants in the component. The weighting takes place with a Sartorius precision balance with an readability of 0,05 mg and an automatic calibration cycle.
The gravimetric result is the mass of the contamination and give no information about particle size distribution in the filter membrane.
For exact weighting it is necessary to preparate and dry the analyse filter very accurate. The drying of the filter membrane takes place in a controllable, non recirculatory oven which is capable of maintaining a temperature of 100°C. Afterwards the filter is cooled down in a desiccator which contains a desiccant substance. The desiccator is placed close to the balance. After a defined time when the filter membrane has reached ambient temperature it will be weighed.