There are also a variety of blow tank configurations that are widely used. Apart from single blow tanks there are twin blow tank arrangements, with both parallel and series arrangements. Blow tanks operating in parallel basically consist of two identical blow tanks, generally placed alongside each other, and while one is being filled the other is being discharged, generally as a means of improving cycling efficiency.Twin blow tanks that operate in series is another term for a single blow tank operating with a lock hopper and this is considered as a separate topic within this chapter.The top vessel is not a blow tank, but is the lock hopper, and this allows conveying on a continuous basis from the blow tank beneath. Due to headroom problems a further development here is to position the lock hopper alongside the blow tank.