07-20M-114R
$ 111.00 USD
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As with any rubber hose below waterline, the PSS bellows must be inspected on a regular basis for any sign of wear, aging or chemical deterioration. PYI suggests preventative maintenance. The PSS bellow should be replaced in six year intervals. During bellows replacement it is recommended the o-rings & set screws in the stainless steel rotor also be replaced.
Bellows may need to be more frequently inspected in an environment where non-sealed batteries emit sulfuric acid. Sulfuric acid vapor will accelerate rubber deterioration, as will an ozonater.
Please be sure to never use the same set screw on the shaft twice. There are two set screws in each of the two holes in the stainless steel rotor. One is tightened onto the shaft and the other is tightened onto the first to lock it in place against the shaft. The set screws are made with a cup at the base that compresses into the shaft ensuring a secure grip. PYI's PSS Maintenance Kit comes with five new set screws included. When re-installing the rotor please use new set screws. In the case that you do not have spare set screws, the set screws in the rotor need to be reversed so there is an unused cup being compressed onto the shaft.
PYI offers a Maintenance Kit that includes the items you need to properly maintain your PSS Shaft Seal. Included in the kit is:
1. Two nitrile o-rings seal the stainless steel rotor to the shaft and will not experience wear.
2. A primary set screw and a backup set screw (2 sets) are used to secure the stainless steel rotor to the shaft.
3. A seal is created between the two flat surfaces of the carbon stator and the stainless steel rotor.
4. Water is fed into the PSS Shaft Seal for cooling/lubricating the seal faces on high speed vessels.
5. The stationary carbon stator is attached to the nitrile bellow, which is attached to the stern tube (shaft log).
The PSS stainless steel rotor is slid down the shaft and is secured to the shaft with set screws at 90° for maximum holding power. Precision tolerances are maintained by computer controlled lathes. The faces have a number 9 micro finish and are perpendicular to the bore to prevent run-out as the collar rotates. The carbon graphite stator will polish the face of the rotor during the first few minutes of operation. The stainless steel rotor should not need to be replaced under normal operating conditions. The stainless steel rotor used on the PSS Type A Shaft Seal is made from 316L stainless steel.
The high density, resin impregnated carbon/graphite stator is a composite that is first mixed, molded and then formed under pressure. The blanks are then baked, machined and lapped. The face of our carbon is finished to a flatness of 4 helium light bands (measured .000044" of variation over entire lapped surface). The grade of carbon used in the PSS has an operating temperature over 500° Fahrenheit (+260° Celsius), and cannot melt if the seal runs dry, unlike a rubber lip seal or plastic face seal. The high density of the carbon greatly increases the longevity and wear resistance. Several commercial vessels have recorded over 40,000 (over 4-1/2 years of continuous operation) engine hours on the same, original components. The carbon should not need to be replaced under normal operating conditions.
The PSS Type A Shaft Seal bellow is made from rubber (Nitrile), and has a temperature rating of -25°F to +225°F (-31°C to +107°C). Nitrile is known for its resistance to weathering. Nitrile rubber is exceptionally resistant to oils and non-polar solvents. It also offers good gas impermeability, abrasion resistance, and better thermal stability than most general purpose elastomers.
