Induction hoppers design

The low-level filling system that has become the most popular in Northern Europe is the induction hopper. This commonly comprises a bowl of approximately 0.5 m dimension into which chemical is poured manually. Most bowls now use a Venturi valve arrangement positioned at the base of the hopper to suck material from the bowl into a liquid flow, that is then directed to the main sprayer tank. An alternative direct connection of the induction hopper to the input side of the main pump is much less popular, because of the potential to damage the pump from extraneous materials that could be introduced via the hopper. A typical induction hopper design will therefore comprise ... 

Container rinsing systems designed for use in conjunction with induction hoppers can be considered as being one of two basic types, namely ... 

Many tests of container rinsing performance associated with induction hoppers are conducted with the systems operating with clean water, whereas for many installations on practical sprayers the rinsing of the container uses liquid from the main tank. It is likely that the differences in residue levels associated with rinsing with clean water or tank contents will depend on the nature of the tank mix formulations, as well as on the design of the hopper and the container rinsing system. 

In the same way that it was recognised that a poorly designed induction hopper would not reduce the risks of operator and environmental contamination (see p. 49) and that a standard relating to system specification and performance was needed (Garnett, 1993) a standard relating to closed-transfer systems for liquid plant protection products has also been produced (Anon., 1996b). This follows the same format as the standard relating to induction hoppers and indicates that in order to comply with the standard, a closed-transfer system must... 

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