About mechanical seal auxiliary facilities - how to determine the amount of flushing

Auxiliary facilities for mechanical seals refer to lubricating, cooling or temperature-regulating, flushing, purifying, diluting and washing away the leakage medium to improve the working environment of the mechanical seals by means of flushing, cooling, filtering and separation.

The primary mode of operation of all ancillary facilities is flushing. How is the amount of flushing determined? Theoretically speaking, the amount of flushing is calculated and determined according to the heat balance principle of the sealing device. The heat generated includes the friction heat of the friction pair of the mechanical seal, the stirring heat generated by the seal rotation, the heat transferred from the fluid in the pump to the mechanical seal, etc.

The ways to dissipate heat include rapid cooling of the gland, jacket cooling of the sealed cavity and natural cooling. The heat generated minus the heat lost, the difference between the two should be the heat removed by flushing. The calculation is troublesome, there are a lot of data selected, and the result of calculating is not very meaningful. According to long-term practice and experience, the flushing volume is 3~30L/min, which can be selected according to the sealing specification (diameter) and the type of medium (see the table below).

According to the selected flushing volume, the flushing volume for volatile medium or medium with higher temperature should be appropriately larger.