Chesterton expanded its offering of NSF 61-certified mechanical seals to include all its single cartridge seals as well as split seals. Previously, Chesterton’s NSF products were limited to the 155 Single Cartridge Seal and the Chesterton 442 with RSC faces. The company recently received approval for all Chesterton single cartridge seals, as well as its flagship Chesterton 442 and 442C split seals.