SUBJECT: Controlling the temperature in the stuffing box 4-6

Many fluids are adversely affected by a change in their temperature, and when this change takes place, seal failure is almost sure to follow. The failure can take several forms:

By keeping the stuffing box temperature within specified limits you can prevent all of the above from happening. These limits vary with each fluid, but they can be obtained from any one knowledgeable about the fluid that has to be sealed.

A balanced mechanical seal incorporating the following features and installed at the proper compression, is your best insurance against a significant rise in stuffing box temperature:

Sometimes, that is not good enough, so occasionally you'll have to come up with some additional method of controlling the temperature in the stuffing box area and between the lapped seal faces.

THE HEATING / COOLING JACKET.

If your pump does not have a heating/ cooling jacket installed, one is usually available from the pump distributor. If possible try to select an oversized stuffing box with a cooling/ heating jacket cast around it. This jacket can be used to heat a product, cool a product, or keep the product within close temperature limits. When using the jacket there are several important things to keep in mind:

THE QUENCH OR DRAIN CONNECTION

Quench and drain connections are available in American Petroleum Institute (API ) type glands. The quench and drain connection (Q) is used in conjunction with a close fitting, non sparking disaster bushing (DB)

THE FLUSH CONNECTION

In temperature control applications we flush in cooled product to control the stuffing box temperature. If you use the pump fluid cooled, or cooled finished product you'll have no problem with product dilution.

THE DUAL SEAL

Another method of providing temperature control is to utilize two seals with the correct temperature liquid circulating between them as a barrier or buffer fluid. Look at the following illustration:

THE HEAT EXCHANGER

The normal procedure is to install the heat exchanger in the discharge recirculation line connected between the pump discharge and the stuffing box. If you elect to use this method be careful of the following:

OTHER CONSIDERATIONS

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