SUBJECT : How to get good mechanical seal life 2-8

Seals that came installed as original equipment in the pump should last until the sacrificial carbon face has worn away. This is the definition of a worn out seal. If a seal leaks before the carbon face has worn down, we call it a failed seal. In practice we find that seals seldom wear out, most of them fail and as a result we spend a good deal of time and money looking for better designs. Wouldn't it be nice if there were such a thing as the ideal mechanical seal? Some customers have spent years looking for this magic seal and their failure rate in seals still exceeds 85%.

Getting a good seal installation is similar to getting a good paint job on an automobile. It's more involved than just the purchase of a good brand of paint. To get a good paint job on your automobile you need to solve four problems:

If you have addressed these four separate problems you can get a paint job that'll last many years. Neglect some of these steps and the life of the paint will diminish accordingly.

Seal application follows four steps also, and if you neglect any of the steps your seal life will be shortened. Here are the four steps you must follow :

In the following paragraphs we'll investigate each of these steps. This brief discussion should encourage you to investigate the subject of seal life in more detail.

Prepare the body

If we were painting an automobile, we would have to first wash the car with a good detergent and then clean the old paint with solvent to remove any silicone wax that could damage the new paint job. We would then do our body work and sand the paint smooth. Priming and more sanding would come next and finally we would wipe the body down with a "tack" cloth to remove any dust that might cling because of static electricity.

This procedure could take many hours or even days, but it's the necessary first step because, without it, the paint wouldnt look as nice as we want.

To prepare the pump for a mechanical seal we want to do a number of things:

Use good quality paint and store it properly.

The final result will be directly related to the quality of the paint you put on the car. We need a paint that has a high percentage of solids, with good corrosion resistance and the ability to maintain a high gloss over a long period of time.

A good seal will incorporate the following features when ever possible:

The paint must be put on correctly.

To do this you would have to mask the parts carefully, control the temperature and dust, do not apply the layers too thick and sand between applications.

There are several problems associated with good seal installation:

Taking care of the paint means frequent washing and waxing.

It also means that you should not park the car in places where opening doors can chip and damage the paint on your vehicle. Following too close to trucks can cause rocks to be thrown into the grill and body. If the car is not garaged, the heat of summer and the cold of winter can shorten the life of any paint job.

We take care of a mechanical seal by providing environmental controls that'll allow the pumping fluid to stay at the correct temperature and pressure to prevent it from changing to a solid, vapor or crystal that could damage the mechanical seal. These environmental controls are especially important with intermittent service pumps because the constant starting and stopping is always harmful to a mechanical seal.

How long can a good paint job last on an automobile?. The answer would have to be many years if you did the four things mentioned in the above paragraphs. Obviously most people do not take the proper care with their investment, and the cars you see on the street are the result.

All companies would like to get better seal life and the method of doing it's not complicated. Take a look at most of the seals you have removed from your pumps and notice that in 85 % or more of the cases, there is very little carbon wear. It's reasonable to expect that with proper attention you should be able to wear out 85% of your seals and experience only a 15% failure rate.

The seal life you get will be directly related to your interest in addressing these four subjects.

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