Subject : The sealing of dangerous fluids.13-5

The definition of fluids includes both liquids and gases and any of these fluids could be labeled dangerous for a variety of reasons:

My seal application technique involves classifying these fluids into one or more of seven specific categories. Dangerous fluids are just one of these categories, but dangerous fluids could be placed into one or more of the other six categories also. Here are the other six categories in case you don't know them:

Dangerous fluids are just like any other fluid you'll be sealing, you must always make two decisions:

In every instance you'll need some type of seal back-up protection to protect personnel in the area when the seal wears out or fails. In most cases it'll mean installing dual seals, but here are some other options:

An A.P.I. gland with a disaster bushing (DB), and a quench (Q) and drain connection that will direct most of the mechanical seal leakage to a collecting tank or out to a flare where it can be burned.

Dual seals with a convection tank supplying liquid to the second seal. The convection tank is filled with a high pressure barrier fluid to ensure that there will be no pressure drop across the inner seal face to the convection tank.

Here is a picture of a typical convection tank. The tank can be either purchased or manufactured in your shop.

Purchased tanks must meet the boiler makers code, meaning that the high pressure requirement might make them very expensive for your application.

Some other back up options include:

Some additional things to consider when you are sealing dangerous fluids.


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