MECHANICAL SEAL SELECTION

NOTE: The blue links do not work on this version of the tutorials. They only work on the CD version

In the following pages I'll be using the word "pump" to describe the piece of equipment that you'll be sealing. If your equipment is anything other than a single stage centrifugal pump with an over hung impeller, the information still applies with a couple of exceptions:

In the following paragraphs, whenever I use the word fluid, I am talking about either a liquid or a gas. If I say liquid or gas, I am limiting my discussion to that one phase of the fluid.

Any discussion of mechanical face seals requires that you have many different types of knowledge. The first is, "should you be converting packed pumps to a mechanical seal?" Seals cost a lot more money than conventional packing and unless you are using split seals, they can be a lot more difficult to install. There is a packing conversion down side.

Assuming you have made the decision that the mechanical seal is your best choice for sealing, you must know how to select the correct design for your application. There are many different kinds of seals to choose from:

There are some very desirable design features that you should specify for your mechanical seals:

We would like to be able to install the seal without having to modify the pump. The seal should be the shortest, thinnest design that will satisfy all of the operating conditions. Once you have the shortest, thinnest design that will satisfy the operating conditions there is seldom a need to modify any seal design.

The specific sealing application will dictate which seal design you should choose. If your seal application falls within the following parameters any stationary or rotating, "off the shelf" balanced O-ring seal should be able to handle the application without any serious problems.

You may have to go to a special seal design if your application falls into any of the following categories:

If any of the following are part of the application, you may need a metal bellows design that eliminates all elastomers.

You should go to a dual seal application if your product falls into any of the following categories:

You need dual seals as a protection for personnel in the area if your product is any of the following categories:

The other places we use dual seals are:

In the Sealing Application section you will learn:

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