Description: System 250 is a high quality, prefabricated chimney system suitable for oil and gas fired appliances with flue gas temperatures up to 7600C continuous firing. System components from 125mm up to 20Omm internal diameter are also suitable for solid fuel appliances. The  system consists of straight lengths and associated fittings and is available  in twelve different internal diameters from 125mm to 60Omm. Construction: System 250 is a twin wall insulated chimney constructed generally as detailed below. The  inner liner is manufactured from stainless steel grade 316 0.46mm, whilst the outer easing is stainless steel grade 304 0.46mm. The insulating material  on internal diameters 125mm -20Omm is a high quality silica based powder  which ensures optimum performance. The  sockets and spigots are manufactured from stainless steel grade 316 0.46mm their construction having bayonet type engagement which lock rigidly together. The  inner liner is lock-formed and fixed to the upper male spigot only. The outer casing is lock formed and is joined to both the male spigot and  female socket end caps. This form of construction allows the inner liner  to expand and contract with the varying temperatures without affecting the outer casing. System 250 in internal diameters from 25Omm - 6OOmm is constructed in the same manner as the smaller diameters. These  diameters are additionally available in a wide range of optional material specifications. This allows total flexibility in terms of application  and budget limitations.