SUBJECT: Sealing products sensitive to a change in temperature or pressure. 8-9

Liquids and gases are both called fluids and a fluid can shorten the life of a seal in two ways;

In this paper we will be considering how small changes in either temperature or pressure will cause one or both of these failures to occur, and learn how to prevent these changes especially when the pump is stopped and often subject to both temperature and pressure fluctuations. In another paper in this series we learned that a change in temperature could:

If you are not using a dual seal with a pressurized barrier fluid, then you will get some sort of a pressure drop across the seal face. A pressure drop could:

If the temperature or pressure of the pumping fluid never changed we would seldom have any application problems. But since pumpage pressure and temperature changes are normal (especially at shut down) we are going to have to become skillful in controlling the temperature and pressure in the stuffing box area to prevent a premature seal failure.

THE HEATING AND COOLING JACKET

If you use this technique be sure to check:

THE QUENCH AND DRAIN CONNECTION is used to heat or cool the outboard side of a single seal and wash away any product the might leak across the faces or build up outboard of the seal.

A DISCHARGE RECIRCULATION CONNECTION connected between the pump discharge and the stuffing box can be used to pressurize the stuffing box area with the discharge pressure available at the pump.

THE DUAL SEAL is another way to control either temperature, pressure at the seal faces, or both at the same time. Take a look at the following diagram:

You can:

HERE ARE A FEW MORE CONSIDERATIONS ABOUT CONTROLLING PRESSURE AND TEMPERATURE IN THE SEAL AREA:

For information about my CD with over 600 Seal & Pump Subjects explained, click here  

 Link to Mc Nally home page