Mechanical seals for pumps.

What are mechanical seals?

Mechanical seals are a type of dynamic sealing to prevent leakage along the power transmitting shaft of a rotating machine. The mechanical seals prevent the fluid (water or oil) from leaking to the external environment (the atmosphere or a body of water).

Technologies behind mechanical seals

The mechanical seal technology is a combination of mechanical engineering and physical properties. More specifically, the core of the mechanical seal technology is tribology (friction, wear and lubrication) used to control the face surfaces where the stationary and rotary rings rub (slide) against each other.

The face materials where the stationary ring and the rotary ring rub against each other are the most important portions as a barrier to the fluid. If the clearance is too small, the friction increases, hindering the shaft motion or resulting in seal breakage. Conversely, if the clearance is too large, the liquid will leak. Consequently, it is necessary to control the clearance in the order of micrometers to prevent leakage, but at the same time ensuring lubrication by the fluid, thereby reducing the sliding torque and avoiding hindrance to the machines’ rotation.

Mechanical seals with improved functionality will not only prevent the liquid or gas handled by a machine from leaking to the outside, but can also improve machine operating efficiency, thereby helping achieve energy saving and prevent environmental contamination. Moreover, in some cases, rotating machines handle media that, in the case of leakage, can lead to a dangerous accident. Therefore, mechanical seals are required to be highly reliable through manufacturing backed by solid engineering expertise.

What is a seal support system?

Seal Support Systems are designed for a specific mechanical seal and set of process conditions. These systems supply either a gas or a liquid to the mechanical seal to regulate the environment in which the seal operates, protecting rotating equipment from damage. These systems have four main functions:

• Provide lubrication to seal faces
• Control pressure and temperature in the seal chamber and seal
• Flush the seal of contamination and/or residue build up
• Prevent system process fluid from leaking to atmosphere