Cyclic flushing is the circulation of an applied sealed fluid by a pumping device (Figure 62).There are two points to be paid attention to. One is the "pumping device", which can be an extra oil station and a sealing cavity to form a closed loop for circulation, or a pump can be installed in the sealing chamber, or the principle of hot siphon to circulate the fluid.Another point to note is the "added sealed fluid". This irrigation is used on double or multiple end seals and not on single end seals. Cyclic flushing is also known as the "external circulation".