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Kind of mechanical seals which is divided into several
Time : 2019-07-26 Hits : 311
1.push mechanical seal and non-push mechanical seal
Push-type
mechanical seal refers to the secondary seal of the mechanical thrust
along the shaft or sleeve to compensate for the wear of the sealing
surface of the mechanical seal, usually the spring-loaded mechanical
seal.
A non-push
mechanical seal for secondary sealing is secured to the shaft of the
mechanical seal, typically a bellows mechanical seal.
2.balanced and unbalanced mechanical seal type mechanical seal
The
mechanical seal seals the pressure acting on the ring to form a closing
force, and the liquid film is formed between the opening force of the
end face. Load factor K> 1, sealed unbalanced mechanical seal.
General unbalanced mechanical seals can only be used for low pressure.
When the pressure is greater than a certain limit, the liquid film
between the sealing surfaces will be extruded. The film in the
lubrication loss and the role of high load, sealed mechanical seal is
about to be destroyed. Unbalanced mechanical seals can not be balanced
by the action of the liquid on the end face of the face and the pressure
increases as the fluid pressure increases.
Load
factor K <1, the seal is balanced mechanical seal. Balancing the
mechanical seal shaft seal the built-in step, so that the radial inner
seal surface extension movement, but does not reduce the width of the
sealing surface. The seal opening force is constant, but due to the
presence of a large torus exposed to the liquid, a considerable portion
of the closing force is balanced. Balance Mechanical Seal External Seal
Balanced Method Other Force In the opposite direction, on the other hand
has the same built-in mechanical seal. In this case, increase the share
of the hydraulic closing force to offset the mechanical seal between
the film opening forces. The balanced mechanical seal can be partially
balanced by the end face of the liquid surface effect, with the pressure
increasing slowly as the fluid pressure increases. General non-balanced
mechanical seals can only be used for low pressure, but the lubrication
performance is poor, low boiling point, easy to medium steam and high
speed conditions, even under low pressure should also use balanced
mechanical seal. As the mechanical seal is not balanced, the mechanical
seal chamber when the pressure increases, the seal between the liquid
film will be squeezed out, the mechanical seal surface quickly damaged.
Balanced mechanical seals can be used for a variety of pressure
conditions.
3.no pressure double pressurized mechanical seal double mechanical seal
Single
mechanical seal only a pair of friction, simple structure, easy
manufacturing, easy disassembly, generally only set the flushing system,
no external seal liquid supply system.
The
double mechanical seal (formerly known as the double mechanical seal)
means that there are two pairs of friction pairs, the structure is
complex, the need for external sealing liquid supply system, pressurized
double mechanical seal through the high than 0.5 ~ 1.5bar medium
pressure isolation chamber fluid, Block, lubrication, etc., in the
internal seal of the liquid seal. No pressure double seal (formerly
known as series seal) means that there are two pairs of friction pairs,
the structure is complex, the need for external sealed liquid system, no
pressure double sealed sealed chamber buffer is not pressurized, the
process medium lubrication internal sealing effect.
In
general, the preferred use of single mechanical seal, single mechanical
seal structure is simple, easy to use, low prices. However, in the
following cases, the preferred dual mechanical seal is preferred.
(1) toxic and dangerous media.
(2) high concentration of H2S.
(3) low temperature volatile media (such as liquefied petroleum gas, etc.).
With
the increasing importance of health, safety and environmental
protection, the number of non-pressurized double mechanical seals
increases year by year. The non-pressure sealed double mechanical seal
can be used for toxic and volatile dangerous media such as vinyl
chloride, carbon monoxide and light hydrocarbons The Sealed double
mechanical seal (first seal) without pressure is the main seal, the
equivalent of single-ended built-in mechanical seal, single mechanical
seal by the media lubrication and was sealed to play. The sealed chamber
is filled with a water tank to seal the liquid without pressurization.
The non-pressure dual mechanical seal, once the inner seal fails,
results in an improved pressure seal chamber that can be displayed,
recorded or alarmed by a sealed tank gauge. At the same time there is no
pressure outside the seal double mechanical seal and sealed shell can
play before the role of liquid leakage.
For some harmful particulate media (corrosive or very powerful medium), consider the following methods:
(1) Use appropriate environmental control measures such as cleaning the + line with cyclone flushing system.
(2) using a double mechanical seal.
Pressure
double mechanical seal blocking fluid pressure higher than the medium
pressure, so that the pump medium does not enter the sealed room.
Pressure sealed within the double mechanical seal to prevent the
isolation, the liquid into the pump room. Thus, when transporting this
viscous abrasive and high temperature medium, the double mechanical seal
is pressurized inside the seal because there is no exposure in the
medium and may not be expensive for alloy production. Pressure outside
the seal double mechanical seal can only play a role in isolation of
liquid leakage to the atmosphere.
4.built-in mechanical seal and external mechanical seal
Built-in mechanical seal: mechanical seal installed in the sealed chamber.
External mechanical seal: refers to the mechanical seal installed in the sealed room outside.
Due
to the built-in mechanical seal effect is better than the pressure to
increase the pressure, the built-in mechanical seal leakage direction
and centrifugal force in the opposite direction, it is usually made of
built-in mechanical seals. Only when there is corrosive media, and
because I do not want to consider the use of pressurized dual mechanical
seal, consider the choice of external mechanical seal.
5.rotating mechanical seal and mechanical seal fixed
The rotary mechanical seal compensating part rotates with the shaft mechanical seal.
The static mechanical seal compensating member does not rotate with the shaft mechanical seal.
Usually
the rotating mechanical seal is made, but at a large shaft diameter,
high speed, the sealing peripheral speed is 25 m / s, the centrifugal
force is large, and because the spring needs to balance the other
rotating elements to produce high stirring power consumption is also
large, Use a static mechanical seal. In addition, if the medium is
easily crystallized while stirring, it is also recommended to use a
static mechanical seal.
6.single, multi-spring mechanical seal mechanical seal spring
Single
spring mechanical seal, simple structure, can play a role in the
spring, but the surface pressure is not uniform, not suitable for
high-speed operation.
Multi-spring
mechanical seals, complex structure, can not play a role in the spring,
and even high-speed operation will face pressure. In general, it is
recommended to use a multi-spring mechanical seal.
