Armstrong's 6900 IVS range has been extended to offer booster sets up to 25 bar, and variable speed above 7.5 kW. The motor size limit is 45 kW, but there is a choice of 2, 3, 4, or 5 pumps for each set to suit the widest range of applications. The 6800 IVS series of booster sets is designed for buildings such as schools, hotels and hospitals, and design features such as Soft Fill enable the range to be used in high-rise residential and commercial buildings. The Soft Fill feature is an additional valuable advantage. It reduces the risk of water hammer associated with rapid exhaustion of air from piping systems – for example following a mains power failure where attempted water draw off leads to air entering the system. Traditionally booster sets are designed to reach their target pressure as soon as possible, but this can lead to hydraulic shock damage in this sort of situation. Armstrong’s Soft Fill feature, however automatically controls the pump speed in these instances and ramps up gradually to a fill setpoint. As pressure increases are controlled, trapped air can be released, and water introduced to the system, in a gradual manner, without damage to fittings. The minimum fill time can be adjusted to suit site conditions. After initial start-up, when the system is in normal use, the booster set reverts back to its usual working conditions, reaching target pressures as quickly as possible.