The PYI PSS Shaft Seal Packless Sealing System is a dripless stuffing box and packing gland replacement for sailboat and power boat drivetrains.

The PYI dripless shaft seal is a mechanical seal that uses a self-aligning carbon-graphite stator to ensure a 100% watertight seal with proven reliability.

This packless seal will eliminate shaft wear and minimize corrosion.

The PSS Dripless Shaft Seal is the number one selling marine mechanical seal worldwide and is installed as standard equipment by many of the world’s most reputable boat builders & yards.

How Does The PSS Mechanical Shaft Seal Work?

The use of PSS dripless shaft seals

While it is obviously a better decision to keep water out of your boat than let it in, the majority of engines built today use a system of dripping to allow seawater into the engine and cool the components.  This seawater corrodes or contaminates many parts of the engine, meaning the choice between overheating and slow destruction of an engine presented a lose-lose scenario to boat owners.  Pss dripless shaft seals remedy this problem by using a fitting to cover the passage to the interior of the engine.  This brand is the most well-used in today’s marine market.  Many of the best boat construction companies and shipping yards utilize this simple seal, and it has been certified by numerous different companies that construct nautical machinery.

Whether you own a boat, rent a boat, or plan to start a nautical hobby, you should know about what a pss dripless shaft sealer can do for a boat’s engine.  A seal can take out the process of repair, adjustment, and price that comes into packing type gland units that allow small quantities of water to enter into the engine.  The standard rate of one drip per minute may seem entirely harmless, especially since the heat of the engine keeps the moisture from accumulating, but the chemicals and saline within the water do far more to harm an engine than the water itself.  Using pss dripless shaft seal technology to eliminate this water completely — the seal makes the unit entirely water tight — helps to keep the propeller shaft from further wear and tear.  What’s more, the unit can be retrofitted in order to accommodate shafts that vary from twenty to one hundred fifty millimeters.

The seal itself sits between a steel rotor and a carbon flange.  While the rotor turns, the flange does not, and a seal is needed to prevent movement from harming either part.  The rotor works to exert force on the bellows and the pss dripless shaft seal compensates for the constant movement.  Instead of requiring fluid to cool it, the polish of the gears keeps water from passing through and reduces the friction that causes more heat.  Attaching a stainless steel collar to the shaft keeps the rotor, the shaft, and the rings itself from wear and tear during a motor’s shelf life.  Indeed, many owners report that this dripless marine shaft seal can keep moisture out of their boat years after it has been installed.

Components of marine shaft seals

High-quality marine shaft seals have several components.  Each of these must be made of durable and appropriate materials if the shaft seal is to provide the characteristics that boating enthusiasts expect.  A marine shaft seal should be watertight even when the engine is producing a great deal of vibration.  It should also do its job without the boater needing to provide ongoing, regular maintenance.  To accomplish all this, a marine shaft seal’s different parts must all work together effectively, which is only possible when high-quality materials are used.

The flange

The flange should be composed of high-density graphite, also known in the trade as high-density carbon.  This material can withstand temperatures up to 500 degrees Fahrenheit.  High-density carbon also means excellent resistance to impact damage as well as to ordinary wear and tear.  Shape is also an important consideration; the flange must be machined to a precisely determined shape so that a perfect seal can be formed.

The O-rings

The O-rings in PSS shaft seals are made of nitrile, a substance that possesses great resistance to petroleum derivatives.  Some rubbery materials will actually dissolve in the presence of petroleum, but not nitrile, which can also operate at a wide range of temperatures.  In addition, materials made of nitrile are difficult to tear.  This is essential if marine shaft seals are to remain watertight.

Other portion of PSS shaft seals include a rotor made of stainless steel, set screws, double hose clamps, and a high quality bellow.

Watertight Marine Shaft Seals

Although all boats in use are at least partially submerged in water, every boating enthusiast knows that there are parts of a boat that should not be exposed to water.  Keeping water out of the propulsion system is the job of a shaft seal.  A quality marine shaft seal will not only be waterproof, however; it will also need no maintenance.  After all, a shaft seal that needs periodic maintenance will eventually fail to receive it in a timely manner.  This could lead to failure.  It is far better, therefore, for boaters to use only shaft seals that are maintenance-free.

How a Shaft Seal Works

A mechanical shaft seal depends on a surface that is able to turn or rotate in order to create contact with a non-moving surface.  In many quality marine shaft seals, the non-moving surface consists of a carbon flange.  Against this is turned a rotor made of stainless steel.  Because the seal is held closed by water pressure, vibrations caused by the engine will not affect the seal.

The Carbon Flange

To construct a quality marine shaft seal, a simple square of carbon is insufficient.  Instead, a carbon or graphite flange is manufactured from advanced composite materials and precision-machined to the exact shape necessary.  In operation, the face of the flange will slightly abrade the face of the stainless steel rotor during the first few minutes the two are in contact.  This action leads to a “polishing” of the rotor face that enables a perfect seal to be formed.

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.

The Flange

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.

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.