The Best Marine Shaft Seals
One of the most important elements in a boat propeller system is the shaft seal. Marine shaft seals are a mechanical seal created when a surface in circular motion turns against an unmoving surface.
Packless Sealing System Shaft Seals
PSS shaft seals are a specific kind of seal that use a carbon flange as the stationary element held against a turning rotor made of stainless steel. The rotor turns along with the propeller shaft. These seals are superior to other kinds because they leverage water pressure in order to maintain continuous contact between the stainless steel and the carbon. This results in a seal that is completely watertight even when the boat motor is producing heavy vibrations.
Another advantage of the PSS shaft seal is that it needs no maintenance to stay watertight. Boating enthusiasts recognize the inherent benefit in boat parts that can be installed once and thereafter work as intended without requiring periodic lubrication or other kinds of assistance. This maintenance-free aspect of PSS shaft seals is due in part to the use of O-rings made of nitrile. O-rings are circular rings that are manufactured as a seamless whole, with no cracks or gaps, making them less likely to fail than rings that have even a microscopic seam joining them together.
The Advantage of Nitrile
The nitrile material is long lasting and has proven to be resistant to various kinds of damage. Unlike rubber or latex, for example, nitrile will not degrade in the presence of petroleum products. Neither is it susceptible to damage from variations in temperature.
PSS Shaft Seals: Advantages
Among marine shaft seals, no other type sells better across the world than PSS shaft seals. These marine mechanical seals are even included by default by many of the world’s finest boatyards, whose expert craftsmen consider them to be standard equipment. PSS stands for “Packless Sealing System,” which is an excellent description of the technology that makes these seals so exceptional. These marine shaft seals function without as much constant attention as other kinds of sealing systems. In particular, PSS marine shaft seals do not need to be adjusted often and they free boating enthusiasts from the need for frequent maintenance.
In addition, a PSS Shaft Seal is completely watertight, which means that water will not accumulate in the bilge. This feature also helps to cut down on wear and tear to the shaft of the propeller so that boating enthusiasts can enjoy a trouble-free watercraft experience for a long while to come.
PSS Shaft Seals are simple to install, even in retrofit situations, and can fit shafts as small as ¾ inch and as large as six full inches or 150 mm across. In essence, the PSS marine shaft seal consists of a face seal between the two flat surfaces provided by a carbon flange, which remains stationary, and a rotor, which rotates. The shaft seal serves to compensate as the propeller produces thrust. This helps to eliminate not just problems caused by vibration, but also those that are a result of small misalignments. A key part of these seals is the use of O-rings that rotate along with the shaft so that they will not wear down over time.
Parts of a Marine Shaft Seal: The Flange
Boating enthusiasts with more than a casual understanding of their boats and motors know that marine shaft seals play an essential role in helping a propeller do its job to full capacity. PSS shaft seals are comprised of several components that require engineering to exacting specifications so that the system works as intended.
High quality marine shaft seals feature a flange made of carbon fabricated to have a high density. Some PSS shaft seals are advertised as having flanges made of “graphite” instead, but this term simply refers to a particular crystalline structure of the element carbon. When installed, the face of this carbon or graphite flange will rub against the rotor face of the shaft seal when the propeller is first switched on. This is by design, not coincidence; the rubbing action guarantees that a flawless seal will be established.
This aspect of the flange explains why “high density” carbon is so important. The rubbing action will quickly wear away or damage the flange itself if it is made of material that is not extremely hard and durable. Flanges made of high-density carbon or graphite have excellent wear resistance and can perform their duties for a long time. In addition, the carbon helps to prevent overheating incidents inside the shaft seal, as carbon can withstand temperatures as high as 400 degree Fahrenheit. When flanges are made of cheaper materials, such as synthesized plastics and their derivatives, overheating can become a real concern.