What is a double mechanical seal? - LEAK-PACK

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WHAT IS A DOUBLE MECHANICAL SEAL?
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Double Mechanical Seal
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BRIEF DESCRIPTION ABOUT DOUBLE MECHANICAL
SEAL  Amongst the several types of mechanical
seals, double seals are preferred for maximum
sealing safety. The seals reduce the possibility
of leakage of gas or fluid being handled in
mixers or pumps to almost zero. Hence, in the
applications that need zero emission compliance
or 100 safety guarantee, the double seals are
the best choice. When properly installed and
maintained, they offer a complete service
guarantee.
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Since the double seals give the total control
over the fluid film over the seal faces and the
operating environment, they serve for quite a
long time as compared to the single seals. THE
WORKING MECHANISM OF A DOUBLE MECHANICAL
SEAL The double seal uses a couple of primary
seals and a buffer fluid area or barrier in
between the two layers. Each primary seal has two
parts a soft and narrow stationary face and a
hard and wide rotating face. The soft seal shows
wear and tear whereas the hard part maintains the
integrity of the seal when it is operational.
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• APPLICATIONS THAT USE DOUBLE SEALS
• To stop a pollutant or hazardous material
  reaching the surroundings
• To prevent leakage of some precious process
  fluid product
• To extend the life of the seal by controlling
  the type of fluid film on the faces of the seal
• To keep the mechanical seal secure from the
  atmospheric conditions
• To avoid contamination of the process media even
  if one seal fails

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• In the situation of inboard seal failure or
  scheduled equipment repair, double seal acts
  backup seal
• In the applications where no reliable and stable
  lubrication of the seal face is offered by the
  process fluid, it works as an alternative. The
  examples are non-settling slurries, viscous
  fluids or gaseous media
• To extend the life of the seal it is essential
  to control the fluid film that gets into the
  contact of the seal face. By this, ideal
  pressure, temperature and lubrication are
  achieved.
• When the double seal is installed, it must
  contain the environmental support and control
  system. It is nothing but a buffer or barrier
  fluid. It is stored in a separate tank and
  supplied to the seal faces. It keeps the faces
  cool and lubricated.

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The level of the fluid and pressure is crucial
for the safety of the system and the environment.
It can manage the operating temperature,
lubrication and isolate the seal from external
conditions. Double seals are used in various
situations when safety is the prime
concern. Also Read   How does a mechanical
seal works? What is a Mechanical Seal in a
Pump? What is the difference between Mechanical
Seal and Gland Packing?
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