Depth filter sheets are used in sheet filters. When inserting, the filter sheets must be handled with care to eliminate distortion or abrasion. Never use a damaged filter sheet. To ensure correct use, place the smooth side of the filter sheet against the filtration plate (i.e. downstream). The rough side of the filter sheet faces the liquid to be filtered (i.e upstream). Prior to first filtration it is recommended, where possible, to pre-rinse with 50 L/m2 of clean water at 1.25 times the flow rate. During pre-rinsing, check for leakage and re-tighten if necessary.