Seal Flush Rates

The following order of magnitude rules of thumb are in common use:

• absolute minimum of 1/8 gpm
• minimum flow that results in a 15 °F temperature rise in the flush
• recommended flow of 1 gpm per inch of seal size.

There are obvious problems with any such simplistic guidelines. For example, under certain conditions, seals can operate with no flush. The 15 °F temperature rise guideline is a rule of thumb for water.   For other fluids, the following temperature rises are often used:

• water – 15 °F
• light hydrocarbons – 5 °F
• oils – 30 °F

Finally, although 1 gpm/inch is a useful and convenient guideline, pressure and shaft speed obviously should be considered when recommending the flush rate.