Series 12B2 are multi spring reverse balanced seal, which are externally mounted . These seals are designed to handle corrosive or abrasive media , as the metal components of these seal do not come in contact with the media to be sealed. Due to its compact design neither radial nor axial extra space is required for installation. These seal can also be installed in double back to back arrangement as internal seal. Though the pressure of the barrier fluid goes down this seal will not allow the process fluid to get mix with barrier fluid, hence it is called a reverse balanced seal.