Waterline builds two basic designs of the Twister. The first, designed for a permanent installation, has a 3” port intended to provide a means to keep the area around the swivel mechanism clear of solids buildup, by allowing either cutter to be introduced or a vacuum source to be applied, or both. For a temporary installation for tank cleaning, this feature is not relevant. So our second basic design has a 6” port in case suction needs to be taken through the manway and circulated through the pump and back into the Twister discharge. In that case, care must be taken to avoid cavitation on a short circuit.