How to determine the right seal for my application?

Here are some questions that will help identify the proper mechanical seal for a given application and process:

• What is the temperature range for the process?
• What is the pressure? Suction? Discharge? Stuffing box?
• Is the product viscous? Does it crystallize, solidify, freeze or build up film?
• the product corrosive?
• kind of pump is used in the process?
• size is the pump? What is the pump’s speed?
• What are the shaft and sleeve sizes?
• the pump cavitate or run dry?
• Which mechanical seals are best for a given application?

The best method of specifying the right mechanical seal is to work in cooperation with a knowledgeable representative from your mechanical seal supplier. Take some of the information you’ve developed from the list above, and work with your sales representative to identify the right product and design features.

Generally speaking, a basic, single-cartridge balanced mechanical seal is adequate for applications where stuffing box pressure is less than 300 pounds per square inch (psi), the temperature is less than 400°F, and the shaft size is from 1 inch to 4 inches. Conditions in excess of these parameters, along with other requirements, might necessitate a special seal design. Double cartridge seals are best in processes where temperature and emission control are critical factors. This is typically the case when working with material that is toxic, radioactive, explosive, or is categorized as a pollutant.²