God Damn that was well put :biggrin:Originally posted by BOUNCIN89MERC2LOW97LHS@Dec 18 2003, 02:48 PM
They just add a little "positive pressure" on the upstream side of the pumphead. Usually gravity is the only thing feeding the fluid through the head. When you pressurize the tank, it just helps keep the flow going into the pump head.
It also helps keep your pump head from cavitating (sucking air). Even foamy fluid cavitates pump heads. The added pressure causes most foaming to rise to the top of the fluid to keep if from being sucked into the pumphead inlet.