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Technical specification
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==Technical specificationConstruction, operation & maintenance==Large collectors are usually 12 m wide and >4 m highOnce a polypropylene net is obtained, use it correctly in a double layer. The This is normally either polypropylene or polyethylene, u/v protected, with 35% shade coefficient, Raschel mesh covers the upper 4 m of the collectorweave, giving and a collecting surface of 48 m2, providing fresh drinking water for rural communities1mm fibre size. Efficiency increases with smaller mesh sizes and fibre width.
Net area needs to be large enough to collect the required amount of water. Typical dimensions per net might be 12m long x 4m high (48m2). Typical water production collection rates from a fog collector range from 150 vary according to 750 the site but seem to average out at anywhere between 2 litres up to 5 litres per m2 per day but some schemes are capable of producing 2,000 with maximums up to 5,000 10 litres per m2 per day. Efficiency of collection improves with larger fog droplets, higher wind speeds, and narrower collection fibers / mesh width. In addition, the mesh should have good drainage characteristics.
Space the nets at 5 metre intervals along the contour (horizontally) and at a distance equal or greater to 60 times the fog collector height in an uphill/downhill direction. This allows for the most efficient collection of fog. It also means that wind damage is less likely compared with collectors that are joined together. In general, these flat units are good for wind speeds up to 20m/s. Cables should be protected within garden hose to prevent them causing erosion of the structure.
Typical water production rates from a fog collector range from 150 to 750 litres per day but some schemes are capable of producing 2,000 to 5,000 litres per day. Efficiency of collection improves with larger fog droplets, higher wind speeds, and narrower collection fibers / mesh width. In addition, the mesh should have good drainage characteristics. In high winds, nets would normally be taken down as part of normal operation and maintenance.
====Maintenance====
A polypropylene mesh has a lifetime of about ten years. In Nepal, operation and maintenance is difficult due to the unavailability of spare parts (mainly polypropylene mesh). Hence keeping stock of mesh and other spare parts is highly recommended. In high winds, nets would normally be taken down as part of normal operation and maintenance. Otherwise where fog collectors are remotely located, different designs are being researched which may provide increased robustness.
==Cost==
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