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A double mechanical seal consists of two independent seals mounted within a sealed chamber outside the pump, which is flushed with an independent supply.  A dual mechanical seal has two primary seals with a barrier or buffer fluid area in between. Each primary seal typically consists of a softer, narrower stationary face accompanied by a harder, wider rotating face. This arrangement enables the softer seal to wear while maintaining the integrity of the harder faced seal during service. These seals often use two rotating seal faces and two stationary seal faces. The fluid is provided between these two seals at a lower pressure than the sealed fluid (known as buffer fluid) or at a pressure higher than the sealed fluid (known as barrier fluid). The fluid provided to the double cartridge mechanical seal allows the seal to survive in lethal, explosive, carcinogenic, hazardous, adhesive, or extremely viscous fluids. This makes dual seal mechanical seal ideal for sealing hazardous liquids, liquids with abrasives or liquids that are corrosive, as the seal faces only see clean lubrication greatly increasing dual mechanical seal life. 


Three ways seal faces are arranged in double mechanical seals: Back-to-Back, Tandem, and Face-to-Face.

● Back to back

Two rotating seal rings are arranged to face away from each other. This is the original concept of a dual mechanical seal. The lubricating film is generated by the barrier fluid. This arrangement is commonly found in the chemical industry. In case of leakage, the barrier liquid penetrates the product. 

● Tandem

This configuration occurs when two sets of seal rings are identically orientated and mounted in series. This configuration is often referred to as the “in-series seal face arrangement” or “face-to-back.”  It is commonly used in dual mechanical seals. By using a buffer fluid with pressure to lower than process, the dual mechanical seal can reduce the pressure differential across a single set of seal faces.

● Face-to-Face

Face-to-face seals can be used when the equipment is space-constrained. The spring-loaded rotary seal faces are arranged face to face and slide from the opposite direction to one or two stationary seal parts. In this configuration, a portion of the seal is mounted in the seal chamber and the remainder is mounted outside of the seal chamber. This is a popular choice for the food industry, particularly for products that tend to stick.


Dual mechanical seal is mostly used inflammable, explosive, toxic, granular, and lubricating medium. The pump products that use double mechanical seal are fluorine plastic centrifugal pump or IH stainless steel chemical pump, etc. As a professional China mechanical seal manufacturer, Wendong's dual seal mechanical seal has independent seal-face designs, to enhance safe containment of process fluid in the event of damage to any individual sealing element.


WenDong specializes in produce mechanical seals and custom mechanical seals solutions. By utilizing our extensive expertise, we can provide a complete solution to your challenge.

Chehe Industrial Park Shiqi Town Ningbo Zhejiang, China


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