Media filters

Amiad media filters are no longer available; these products have been replaced by media filters from Netafim.

Media filters have proven themselves more than adequately in practice. The thick sand layer in the filter creates a unique depth filtration system in which the contaminant particles in the water are trapped by the sand bed. Contaminated water flows downwards through the sand bed, and the clean water runs vis the filtration nozzles in the baseplate to the outlet from the filter.

In many cases the passage between the sand particles is larger than the contaminant to be trapped. The binding in particular of organic contaminants such as algae to the sand is caused by the attraction between the particles and not (only) because the passage is smaller than the contaminant particle.

This means that the flow velocity has a great influence on the function of a media filter. For standard filtration, a flow velocity of max. 50 – 55 m/h is maintained. For UV filtration that requires finer filtration, a flow  velocity of ± 10 m/h is maintained. The ultimate filtration capacity and quality of the media filter is determined by the relationship between the flow velocity and the surface area of the sand bed.

The media filter is cleaned by back-flushing. Water is pumped in the opposite direction through the filter, loosening the sand bed. The contaminant particles are thereby separated from the sand bed and flushed away via the drain line. This back-flushing can be performed manually or automatically. The back-flushing velocity for standard sand is 35 – 40 m/h (for the exact back-flushing capacity, refer to the technical specifications). Standard filter sand has a grain size of 0.6 – 1.0 mm. Adaptation of the sand fraction has less influence on the filter fineness than an adaptation of the flow velocity through the filter.

The media filters are equipped with sufficient inspection openings so that inspection or replacement of the sand layers can be easily carried out.

Characteristics

• Depth filtration thanks to deep sand bed
• Dimensions 16” to 60” with threaded or flanged connection
• High capacities from 8 to 90 m³/h
• Simple manual or automatic back-flushing on the basis of pressure difference and/or time
• Standard grain size from 0.6 - 1.0 mm (not supplied)

Application

Media filters are employed as main filters in drip irrigation, sprinkling and in UV installations, or as prefilters.