Shaft Seals  

SHAFT MECHANICAL SEALS

Mechanical seals have become widespread due to the following positive properties: they do not require maintenance during normal operation; operate with little or no leakage per se; are highly durable; the ability to operate in harsh conditions - under pressure, temperature and in aggressive environments and liquids. Any vessel can easily be fitted with a mechanical seal for shaft sizes from 3/4" to 6-1/2" (20mm to 150mm).

HOW IT WORKS

The sealing surface is created between the flat surfaces of the rotating stainless steel rotor and the stationary carbon stator. The stationary carbon stator is attached to the front side of the bellows with hose clamps, while the rear end of the bellows is slipped onto the stern pipe and secured with hose clamps. The stainless steel rotor compresses the bellows before the rotor is secured to the shaft with set screws. This compression (preload) maintains constant contact between the two flat faces of the stainless steel rotor and carbon stator, allowing the mechanical seal to compensate for the alternating back and forth movement due to propeller thrust. In addition, the carbon stator is bored to the diameter of the shaft, allowing it to float around the shaft and thus compensate for most misalignment and vibration problems.