Magnetic Fluid Seal System For Control Of Pump Fugitive Emissions

Abstract

Pump fugitive emissions can now be controlled to near zero levels by the use of a simplified dual seal system. A magnetic fluid secondary seal traps any vapors that leak past the primary mechanical seal. This arrangement requires no external support equipment other than venting the vapors to a suitable disposal or recovery system. Magnetic fluid seals have provided hermetic sealing for various gas applications over the last 20 years. One common use is as exclusion seals for magnetic disk drives. Adaptation of this technology to centrifugal pump applications required an extensive development effort. Laboratory tests show maximum emission rates of less than 3.0ppm of organic vapors. Field evaluations on process pumps confirm the feasibility of using this technology to achieve strict emission control. Magnetic fluid seals are nonwearing devices. Improved technology allows renewal of the magnetic fluid while the pump is in operation. The magnetic fluid barrier provides a hermetic seal even if the mechanical seal leak rate increases due to wear.