Mechanical Seals


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What is a Mechanical Seal?

A basic mechanical seal is not a complex device. It consists primarily of a rotary seal face with a driving mechanism which rotates at the same speed as the pump shaft, a stationary seal face which mates with the rotary and is retained using a gland or in some pump models an integral stuffing box cover, a tension assembly which keeps the rotary face firmly positioned against the stationary face to avoid leakage when the pump is not in operation, and static sealing gasket(s) and elastomers strategically located to complete the seal assembly.

Why Mechanical Seals for Pump?

Mechanical seals are engineered for most  pumps, mixer and agitator applications in maintenance. In many cases the designs have been proven to be workhorses over years of use. In others seals must be designed for evolving industrial demands.

Mechanical Seals deliver a full range or rotary configurations and component materials - to handle virtually and fluid moved by any equipment. When you specify engineered mechanical seals you have the advantage of the most advanced mechanical seal technology, the latest in field proven design and when working with an outside sales force there is hands on technical support.

Rotating face units are the dependable mechanical seals answer for worn equipment when your shaft mechanical seals must be replaced.  They are ideal for new equipment designs or to improve the usefulness of existing equipment by converting from pump packing to mechanical seals.

Single Spring Seals

Cartridge Seals

Burgmann Replica seals

Metal Bellows Mechanical Seal

Features of Mechanical Seals:

*Invisible leakage
*Less friction/power loss
*No to little wear on the shafts or sleeves
*Flexibility - to accommodate shaft deflections and "End Play"
*No period maintenance
*Long Life

In practical use, the basic rotating face mechanical seal principle is adaptable to serve a tremendous number of sealing needs: standard mechanical seals can suit most requirements-including temperatures to 500 degrees F and shaft speeds to 3600 RPM through the choice of secondary seal and the combination of seal and seat face materials which are offered.  Seals can be ordered in balanced configurations to seal pressures above 200 psi, or used in a multiple for extremely high pressures or especially severe fluid services....Special mechanical seals can be furnished to meet the most demanding of industrial applications considering pressure, temperature, speed or fluid.

American Seal and Packing

Mechanical seal designs range from the work horse "single spring" mechanical seals, to highly engineered double cartridge seals for extreme applications.  The basic of each type follows:

Single spring mechanical seals:

Utilize a single spring coiled in a right of left hand design to accommodate left and right hand turning pumps. They have the flexibility to accommodate misalignment, shaft deflection, and break away shock loading.  It resists clogging in extremely viscous fluids.

All mechanical seals are constructed of three basic sets of parts:

1) A set of primary seal faces: one that rotates and one that remains stationary.

2) A set of secondary seals known as shaft packings and insert mountings, such as o-rings, rubber boots, PTFE or Grafoil wedges, or V-Rings.

3) Mechanical Seals have hardware including gland rings, collars, compression rings, pins, springs, retaining rings and bellows.

Mechanical Seals can be classified by Arrangement

Mechanical Seals can be classified by Design

Mechanical Seals by arrangement

mechanical seals by design

A mechanical seal works though the use of two very flat (generally within 3 light bands flat) lapped faces which make it difficult for leakage to occur (beyond a vapor). As mentioned above one face is stationary and one rotates with the shaft. One of the two faces is usually a non-galling material such as carbon-graphite.  The other will be a harder material providing dissimilar materials making contact and allowing one to be a sacrificial. The softer mechanical seal face usually has the smaller mating surface and is commonly called the "wear nose" of the mechanical Seal.

The Easiest seal to install as a replacement for pump packing is a cartridge type mechanical seal:

The Beauty of cartridge seals are they are self-contained.  Holding all the elements of a mechanical seal set: 

*Rotating Face Seal

*Stationary Seal face or faces

*Shaft sleeve


Cartridge mechanical seals :

Are the easiest seal for a mechanic to install.  Only being required to slide onto the pump shaft and bolt to the pump gland, the cartridge seal cannot be miss installed. 

Cartridge seals must fit the stuffing box  there is a form on under mechanical seals with this and other information on it to help the customer make sure the seal fits there pump.  

Installation of single spring, metal bellows or multiple spring seals require much more effort to be sure of an effective long lasting seal.  Ask your American Seal & Packing sales representative for installation directions. 

Inflatable seal Seals that inflate and deflate in three basic directions of operation: the axial direction, the radial-in direction, and the radial-out direction. Each of these inflation directions has their own set of performance parameters for measurements such as the height of inflation and the center-line bend radius that the seal can negotiate.

If you have any questions please contact us at:  E-Mail about your mechanical seals applications.

Phone: 714-361-1435                                            Fax: 714-593-9701

bellows seals
Single Spring Pump Seal
Swimming Pool Seals
wave spring
Mechanical Seal Catalog




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