The primary purpose of a scrubber on a dry chemical handling system is to clean the air that is vented from the tank. This venting is the critical element to designing a system that will operate reliably. Dust from the dry feed into the tank combined with water vapour in the air leads to build up of solids in the space above the liquid level. This build up can be particularly problematic at the feed inlet as it will gradually restrict the flow into the tank. A well designed scrubber will actively draw air from the tank, remove the dust (retuning it to the tank), and limit build up at the feeder inlet. A slight negative pressure on the tank will also help prevent dust from escaping and building up in the area surrounding the feed system.