Due to health safety and environmental considerations, there is use of tandem seal. Tandem seal is under normal operating conditions. The inboard seal is designed to withstand full product Pressure. The outboard seal operates in a very low pressure, if the heat generated by the outboard seal is high, a pumping device is usually added to create flow from buffer fluid supply tank.

A tandem seal increase on line reliability if the inboard seal failure occurs on a critical piece of equipment, the outboard seal can take over and function until maintenance of the equipment can be scheduled. Alarm systems are available to Caution the failure of seal.