Environment Determines Seal Type

Guide to Mechanical Seal Types and Component Properties - Page 4

The balanced seal has the same opening area as the unbalanced seal, but the closing area has been reduced in relation to the face area. Because force = pressure x area, reducing the closing area reduces the closing force: less heat is generated, and the seal generally has a longer life.

Seals can be further classified in a number of ways. There are four additional classifications of mechanical seals which can be described by distinct characteristics:

Rotary spring, springs or bellows rotate with the shaft.
Stationary spring, springs or bellows do not rotate with the shaft.
Non-Metallic, no metal parts come in contact with the fluid being pumped.
All Metal, metal parts are used exclusively where application temperatures require it.

Temperature Chart

Temperature	Inside		Outside
Temperature	Balanced	Unbal.	Balanced	Unbal.
Up to 250 °F Up to 120 °C	*	*	*	*
250 °F to 400 °C 120 °F to 205 °C	*	*		*
Up to 400 °F Up to 205 °C		*

Pressure Chart

Pressure	Inside		Outside
Pressure	Balanced	Unbal.	Balanced	Unbal.
Up to 150 psi Up to 3.5 kg/cm²	*	*	*	*
150 psi to 300 psi 3.5 kg/cm² to 21.1 kg/cm²		*		*
Over 300 psi Over 21.1 kg/cm²		*

Speed Chart

Speed	Inside		Outside
Speed	Balanced	Unbal.	Balanced	Unbal.
Up to 1500 fpm Up to 7.6 rpm	*	*	*	*
1500 to 3000 fpm 7.6 to 15.2 rpm	*	*		*
Over 3000 fpm Over 15.2 rpm		*

fpm = Feet per Minute
rpm = Revolutions per Minute
psi = Pounds per Square Inch
kg/cm² = Kilograms per Centimeter Squared

Information Guide:

Mechanical Seal Components | Various Seal Designs | Determine Seal Replacement | Environment Determines Seal Type | Seal Composition Limits | Seal Head Types | Seal Seat Types | Seal Face Wear Patterns ||| Water Pumps