08 TECHNICAL INFORMATION | PRODUCT-SPECIFIC SECTION
Dry-air flow rate
Air flow rate through filter discs of various porosities as a function of pressure differential. For filter discs with Ø 30mm
Care and cleaning of filtration apparatus
In addition to the information in the general section, please also note the following guidelines relating to thermal stresses, which apply specifically to filtration apparatus, in order to avoid glass breakage.
Temperature changes (thermal shock), drying and sterilisation
• The maximum permissible operating temperature is + 450°C. • Uniform heating is recommended to avoid thermal stresses and resultant breakages. • Heat glass filtration apparatus with disk diameters of more than 20mm in initially cold ovens or sterilisers only. • The heating or cooling rate should not exceed 8°C/min. • When filtering hot substances avoid temperatures differences of more than 100K; if necessary, preheat the filtration apparatus in a drying cabinet. • Wet filtration apparatus should be heated slowly up to 80°C and dried for one hour before increasing the temperature further. Whenever possible, filtration apparatus should be stood on its rim (stem upwards) to allow air convection between the inside of the vessel and the oven chamber. If placing the filtration apparatus in the oven at an angle cannot be avoided (as in the case of pipeline filters), any support point close to the position of the filter weld must be protected against heating up prematurely by placing heat-insulating material under it.
Cleaning new glass filtration apparatus
Before using glass filtration apparatus for the first time, it should be rinsed with water (if applicable, acid), to remove any minor contamination that may be present.
Mechanical cleaning
In many cases, if no precipitate has infiltrated the pores, simple spraying of the surface (e.g. with a spray bottle) will suffice. Brushes or rubber wipers can also be used to clean the surface of the filter disk. If some precipitate has infiltrated into the pores, then back-flushing of the disk is required.
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