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EFE & GB Nets PO Box 1 Bodmin Cornwall UK PL31 1YJ Phone: 01208 873945 Messages /FAX:
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The Hess sampler is used in similar circumstances to a surber sampler but is even more accurate. A low flow regime is required for the small unit or higher flows and deeper water for the large unit.. The base of the Hess sampler is pushed into the substrate to make a seal. On the large unit substantial teeth can be fixed to cut into the substrate ensuring a good seal. The upstream side is sealed with a large screen filter of preferred size to prevent any invertebrates entering the sampler through drift or when external substrate is disturbed. The downstream side has a net bag fitted with closed, screw on filter ,bottle or dual material filter. Similar to a plankton net in shape, this bag will collect any invertebrates within the sampler area. An expression of the number of invertebrates in relation to surface area sampled can then be calculated. Trials of the large sampler are now complete and it has proved to be very effective and easy to use. Robust enough to use in a tidal estuary where the upstream filtration is severely tested. The upstream filter is removable in 10 seconds and can be washed for re use on many occasions. Each sampler is supplied with 2 upstream filters and one downstream collector of your choice.
The small sampler is 100 mm wide and 400 or 500mm high . The tough large sampler is 300 mm wide and each section is 200 high with extension limited only by the maximum reach of the operator. As these are made to order the purchaser should specify the dimensions and the size of the upstream and downstream mesh. The mesh size does not affect the price if above 53 micron. Prices excluding VAT
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GB Nets is a wholly owned subsidiary of Educational Field Equipment UK Ltd.
Copyright © 2004 Educational Field Equipment UK Ltd.
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