Reversible and two way vacuums are air powered and have the ability to vacuum then with the turn of a valve the compressed air is pumped into the vessel to force the fluid out. The unique design of the Spillrite units means that there is no chance of over pressurisation as any build up of pressure is released through the exhaust of the venturi's. There are many styles of the reversible units that can be fitted to drums as a basic drum pump starting at 20 cfm models right up to the explosion proof models fitted to the stainless steel tanks of the Spill control vacuums and powered by 180 cfm heads.