Water & Wastewater Treatment

www.wwtonline.co.uk | WWT | sepTember 2014 | 37 In the know Getting to grips with water storage A guide to tank specification What you need to consider when it comes to cold water storage When it comes to large volume cold water storage it is important to realise that you have a choice of tank-type and that the one you choose must suit the particular project or installation being working on. It is vital that the tank specified is designed and manufactured to the relevant international and industry standards which include BS EN 13280, BS 1564, WRAS, LPCB and FM Global, the latter two specifically for the fire norman ross direcTor balmoral Tanks fighting sprinkler market. The most common types of cold water storage tanks (CWST) are bolted glass reinforced plastic (GRP) and galvanised steel sectional tanks. The latter are manufactured as cold-press or hot-press panels. Hot-press panels are manufactured as one-piece units rather than having the corners welded as is the case with cold-press, mean- ing there are no welded flanges or corners on the individual panels. The other commonly specified water storage option is the cylindrical galvanised or aluminium bolted steel tank with an internal liner. Cylindrical tanks are supplied as flat sheet panels sponsored by Smart liquid lime www.neutralac.co.uk and take their form as the tank is constructed in the round. All of the above tank-types can be fitted with accessories including pipe connections, ball float and drainage valves, internal ladders, gated ladders and walkways, access hatches, con- tent gauges, immersion heaters, etc. Internal partitions are also available with GRP and steel rectangular tanks The tanks are suitable for storing potable and non-potable water, irriga- tion, rain/storm water and fire fighting sprinkler system water. They are used widely in the utilities, residential, commercial, construction, health care, food processing and agricultural sectors. GrP sectional water tanks (Fig 1) These tanks are built on site by bolt- ing together panels which typically measure 1x1m and 1x0.5m. A sealant is placed between each panel to ensure water-tightness. GRP tanks are generally accredited to 4m in height and can be built to almost any width and breadth. They are commonly used to store water in capacities of 1m 3 -1,000m 3 and insulation options are available. The GRP material should demon- strate resistance to bacterial growth and show a reduced risk of osmotic attack. GRP sectional tanks should be designed to BS EN 13280 (2001) stand- ards and carry WRAS approval for po- table water storage and LPCB approval for fire fighting sprinkler systems. steel sectional water tanks (Fig 2) Each steel panel, or plate, should be manufactured to BS1564:1975 Type 1 (Hot Pressed) standards and bolted to the adjacent panel using an ap- proved sealant. The panel thicknesses depend upon the size and depth of the finished tank and range from 4-6mm. Tanks are built on site to 5m in height and to any length and width giving almost infinite storage capacities. A wide range of coatings is avail- able for both the inside and outside of the tank and include hot dip galvanis- ing and WRAS approved systems. A Drinking Water Inspectorate (DWI) approved coating can be used to meet the Water Supply regulations and insulated panels are also available. Steel sectional tanks are speci- fied over GRP where there is a risk of earthquakes as they are less likely to fracture when seismic activity takes place. They are used by the global food and drink processing industries, Figure 1: Grp sectional tanks are built on site and commonly used to store up to 1,000 m 3 of water

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