This chapter discusses separation equipment that are used to separate streams containing two phases, such as gas–liquid, gas–solid, liquid–liquid, and liquid–solid. This equipment is critical for proper operation of pumps, compressors, and separation processes. For simple gas–liquid or gas–liquid–liquid separators, the four regions of separation are discussed, including the equipment for mist extraction and regions of efficiency based upon gas flow and particle size. Advantages of vertical and horizontal separators are discussed. An overview of filter separators and coalescing filters is provided. Tables of retention times are given for various separations for checking proper sizing. The chapter concludes with an overview of filtration systems.