Creating distance (spacer mesh)
Extruded polypropylene meshes are widely used as feed spacer in reversed osmosis filter installations. Reverse Osmosis (RO) in water filtration is called ultra-filtration and is the process in which water is purified or desalinated by filtering it under high pressure through membranes in spiral wound filter units. These membranes are kept at a distance by using PP extrusion mesh. The feed spacer separates two layers of adjacent membrane sheets, allowing the feed stream to efficiently reach the membranes. The feed spacer and membranes are wrapped around a perforated tube which collects the permeate so it can be taken away.
The bi-planar structure of extruded polypropylene mesh makes it an ideal feed spacer. Polypropylene extruded mesh offers the stiffness to ensure an even distance and support over the whole membrane surface, enabling the necessary flow and a minimal pressure drop. The flatness of our nets limit membrane damaging to a minimum.
Our polypropylene feed spacer nets are produced in a range of several thicknesses, ranging from 21 mil (0,5 mm) to 80 mil (2 mm).
For mesh thickness under 0,5 mm Top Zeven offers woven meshes. However, weaving doesn’t allow high stability like extrusion does. Therefore a highly stable woven mesh would be our co-extruded mesh. Co-extruded polyester mesh is woven from co-extruded yarns; PET yarn with a soft surface which enables fusing of the yarns onto each other through heat treatment after weaving. This makes the mesh stable and enables weaving with thin threads in an open structure, thus creating a very thin and open mesh which is still stable.
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