Selecting the Right Mechanical Seals

What is a Mechanical Seal?

A mechanical seal is used when fluid or gas needs to be contained within an industrial pump, mixer or compressor. In addition, mechanical seals are used when a rotating shaft component is housed in a stationary compartment. Mechanical seals have become a vital part of industrial equipment across many residential and commercial applications.

What makes the Mechanical seal work?

The pressure produced by the pump (hydraulic pressure) forces the seal faces together. The faces are engineered to be perfectly flat with a face OD & ID. That reduces leakage. So that seal faces are lubricated, but leakage is negligible. The spring or springs provide pressure, so there is no leakage when the pump is not running. These springs also ensure that faces maintain contact during vibration or are not parallel.

Residential Mechanical Seal Uses

Hot tubs
Fish Ponds
Dishwashers
Pool & Spa

Commercial Mechanical Seal Uses

Engines
Sea Vessels
Centrifuges
Waterparks
Amusement park
Waterfalls/Fountains

Industrial Mechanical Seal uses

Refinery
Power Plants
Oil & Gas
Mining Industry

The Basics of Mechanical Seal Assembly

A mechanical seal assembly consists of a seal face that rotates in tandem with a pump shaft housed within a stationary compartment containing a stationary seal face. A standard mechanical seal assembly contains a rotating face with a rotating seal to shaft with a gasket (O-ring) and a stationary face sealed in a stationary compartment with a gasket (O-ring)

THE BASIC COMPONENTS OF A MECHANICAL SEAL

A static seal has a rotating seal face retainer on the shaft and is driven with some form of lug or crimped tabs. This face has a secondary seal (usually an O-ring) that seals between the shaft and the retainer or rotating face.
Stationary face container in or on the pump is a way that ensures it is parallel to the rotating face. It has a gasket that prevents leakage into the atmosphere. The face movement is prevented from axial movement by an O-ring or pin.
Spring or springs either behind a rotary or stationary face. A spring or metal bellows tension assembly keeps the rotary face of the mechanical seal securely positioned against the stationary face to prevent leakage and contamination during operation and when the pump is turned off. Static sealing gaskets, o-rings or elastomeric bellows are used throughout to complete the mechanical seal assembly.

The Differences Between a Single Mechanical Seal and a Double Mechanical Seal

Seals come in numerous forms, from single mechanical seals to double mechanical seals. Identify the proper seal for the temperature, application, and environment in which the seal will operate. There is no one-size-fits-all for every application and equipment.

Working With a Mechanical Seal Supplier

Understanding the proper seal for the job is critical to prevent leakage and pump safety. Platinum Performance Products is a mechanical seal manufacturer with over 30 years of experience combined. Selecting the correct seals for your industrial and residential applications. Contact us with your questions at team @3ppumps.com.

Mechanical Seal Application

There are different seals for different applications.

Commercial & Industrial uses. If you have your standard residential application for a freshwater pool or hot tub that can be a specific material / seal. If you were to do salt water with the same pool that would take the same seal but different material. The material has to withstand the heat and or chemicals.

Commercial users – seal would be an upgraded material due to abrasion, corrosion for the application that is possibly used. First question we ask is what are you pumping. Then you can ask what is the high or low temp it gets at. Some might be a hot application so the seal and material will need to withstand the high temperatures.

Mechanical Seal Materials

Different materials (Elastomers) are available for mechanical seals – For example, buna temp range is from -65F to 250F. This is useful for oil, water. The EPR temp range is -50F to 300F. These should not be used in oil or type of grease. They are useful mostly in ketones and alcohols, helium gas. The viton temp range is -20F to 400F. Mostly used in hot water applications because it has chemical resistance.

Prevent Leakage With Mechanical Seals

Leakage refers to visible leakage of the seal. However, in a properly functioning mechanical seal assembly, there should be no visible leakage from the mechanical seals.

Among the different sealing points, the seal between the rotating and stationary seal face is the primary seal to focus on preventing leakage and contamination. This primary seal is a spring-loaded vertical bearing that is comprised of fixed and rotating surfaces rubbing against each other. A form of lubrication, known as fluid film, is applied between the two seal faces. Without the fluid film, leakage will happen due to the surfaces wearing and creating extreme heat and friction, causing the pump to fail.

Mechanical Seal Diagram

In this diagram, you can see that the microscopic gap is achieved using counteracting forces from the spring/hydraulic force pushing the mechanical seal faces toward each other against the pressure of the fluid film that acts to move them apart. Without the hydraulic pressure pushing the faces together, the gap would be too large, allowing fluid to leak out. Likewise, without the fluid film acting to push the two seal faces apart, they would contact each other. This contact between surfaces is known as dry running and needs to be avoided to prevent seal failure.

The Evolution of Mechanical Sealing

Before mechanical seals, a method known as gland packing was used to form a seal between the shaft and the pump. Gland packing uses a braided substrate “packed” around the rotating shaft to create a gap between the moving shaft and the pump operations.

Several drawbacks to this method led to the increased adoption of mechanical seals instead. First, gland packing doesn’t eliminate the friction between the rotating shaft; as a result, the filling wears away, leading to increased leakage. The friction created from the addition of the packing materials also creates excessive heat that needs to be cooled with large amounts of water. Finally, with the breakdown of the packing material, more expenses are incurred to repack the system. 

Benefits of Mechanical Seals

  • Packing can only operate with leakage from the pump it has to leak to liberate the packing. Mechanical seal eliminates leakage between the pump shaft and the stationary seal.

  • It saves money, reduces time and builds sustainability into your operation by no longer needing to “repack” pump shafts and use water for cooling with the gland packing method

  • Process fluid utilization (fluid film) reduces bearing contamination and equipment corrosion

  • Saves power and energy needed to turn the shaft with the friction of the packing. Mechanical seal does not require that. When operating within its parameters effectively prevents leakage and runs with considerably less power.

Platinum Performance Products – Your Mechanical Seals Manufacturers

We sell a wide range of replacement mechanical seals that adhere to the mechanical seal specifications of all major pump brands, such as: Paco, Taco, Goulds, Aurora, Bell & Gosset, Gaso, GOULDS G&L and Myers.

Disclaimer: Platinum Performance Products provides parts that are compatible with or can replace different original equipment manufacturer (OEM) parts. The mention of any OEM names, trademarks, model numbers, or part numbers is purely for reference and does not indicate that we are an authorized distributor or representative of the listed companies and brands. We do not claim any association or affiliation with any of the OEM manufacturers mentioned on our website or in our product descriptions.

For additional information and assistance with sizing, identifying and repairing mechanical seals, contact us at team@3ppumps.com