1Product Support

Basic Sealing

Principles

2Product Support

Mechanical seals

Basic parts

Function of a mechanical seal

Types of mechanical seals

Arrangements

Materials

Operation of seals

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Mechanical seals in Pumps

Stuffingbox

MotorShaft

Coupling

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Basic Parts

Rotating Sealface (1)

Stationary sealface (3)

Secondary sealing elements (2+4)

Spring element (5)

Torque transmission(6)

12 35 46

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Features of Sealfaces

z Solid, homogen materials

z Surface roughness(polished , lapped)

z Hardness

z Facewidth

z Good heat dissipation

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Rotating faces

Solid faces

Inserted faces

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Rotating faces

Composite faces Shrunk in Bonded Brazed Supported

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Stationary faces

Solid

Composite type

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Stationary faces

Mounting 0 Ring mounted

single 0 ring double 0 ring

elastomer cup rigid clamped

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Secondary sealing elements

0-rings

Enveloped rings

Rubber cups

Wedge designs Quad rings

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0-rings: location and compression

Dynamic 0-ring Stationary 0-ring

Dynamic 0-ring7 %

Stationary 0-ring10 - 12 %

Static 0-ring20 %

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Springs

helical springs

wave springs

metall bellows

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Torque transmissions

Form locked transmission

Friction locked transmission

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Function of a seal 1

Closing forces Static closing force Hydraulic closing force

Media Spring

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Function of a seal 2

Media as a lubricant and coolant

Media

Lubrication

Cooling

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Function of a seal 3

acceptable minimal Leakage

Medium

Leakage

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Function of a mechanical seal

Closing forces Static closing force Hydraulic closing force

Lubrication friction cooling

Leakage

Media

lubrication

cooling Leakage

friction

Spring

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Unbalanced / balanced seals

Balance ratio of a seal

k =

necessary to reduce the face load of a seal

sliding face areahydraulic loaded area

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Unbalanced seals

k >1 = unbalanced seal

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Balanced seals

k

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Heat developement of a seal

Face friction

Heat dissipation

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The sealing gap

Media

Frictional heat

Pressurereduction

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The sealing gap

high temperature media

Boiling point

Frictional heat

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Leakage

minimal = is acceptable

is influenced by many parameters

is neccessary for proper seal operation

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Leakage effecting parameters

finish of the sliding faces running in process flatness of the faces face deflections caused by thermal and pressure loads conditions of the secondary seals

vibrations and stability of the maschine operation mode of the plant characteristics of the sealed fluids accuracy of the seal mounting and assembly condition of the equipment

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Types of seals

0-ring seals (pusher type seals)

Bellows type seals

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Single seal arrangement 1

Externally pressurized

springs in product contact

springs without product contact

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Single seal arrangement 2

Internally pressurized

Springs facing awayfrom the product

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Single seal arrangement 3

Stationary seals

springs withproduct contact

springs without product contact

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Seal arrangements

Multiple seals

Back to back face to face tandem

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Double acting seal arrangerments

Double acting seals

z Multiple sealz Faces barrierfluid lubricatedz Back to back or face to facez Pressurized barrierfluid

( P1 + 2..3 bar resp.+10% over P1)

z No product leakage z For aggressive mediaz For solid loaded mediaz For polimerising, sticky mediaz Environmental safe operation

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Tandem arrangement

Tandem seal

z Multiple sealz Function as single seal with safety sealz Quenchmedia

pressureless ( standard ) z Surveyance possibility of sealz Leakagecontrol and drain

QuenchmediaProduct

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Seal materials

Face materials

Secondary seals

Spring element

Construction partsdepending on the seal type

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Seal face materials

Ideal characteristics

resistence to corrosionresistence to weargeometrical stablenessthermal conductivityemergency running capabilityprice competitiveness

A selection is always a compromise

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Burgmann standard materials

Soft faces

Buko 1 = resin impregn. carbon graphite

Buko 03 = antimony impregn. carbon graphite

Hard faces

Bume 5 = stainless steelBuke 5 = ceramic (99%)Buka 22 = silicone carbideBuka 20 = silicone carbideBuka 16 = tungsten carbide

With hard / hard face pairing Buka 22 and /or Buka 16 is used

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DIN standard materials

Soft faces B = Buko 1 A = Buko 03

Hard facesS = Bume 5V = Buke 5 Q1 = Buka 22Q2 = Buka 20

U2 = Buka 16

More details in DIN 24960

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Secondary seals materials

Elastomers

z P = Nitril Butadien Kautschuk ( Perbunan )z E = Ethylen-Propylen-Dien Kautschuk, EPDMz V = Fluor-Kautschuk, FPM, (Viton )z K = Perfluor-Kautschuk, (. Kalrez, Chemraz )

Elastomers, wrapped ( enveloped )z M1 = TTV, Viton double PTFE envelopedz M2 = TTE, EPDM, double PTFE enveloped

Produkt

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Secondary sealing elements

Non-Elastomers

z G = Statotherm, pure graphite

z T = PTFE (Polytetrafluorethylen)

z Y1 = Burasil, gasket asbestos free

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Springs and construction

Springs

1.4571 = stainless steel, 316 Ti 2.4610 = Hast. C4

Construction

1.4571 = Stainless steel, 316 Ti 2.4610 = Hast. C4 1.4462 = Duplex SS, 329

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Operation I

Operation with productcirculation

Flushing into the stuffingbox

from discharge

external source

to the seal face

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Operation I : Flush

Flush

- Increase of pressure in the stuffingbox

- Temperaturreduction

- Avoiding of deposits

- Reduction of solids content

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Operation II

Packing

Throttlebusch

Lipseal

Mechanical seal

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Operation II Quench

Operation with an external quench with different medias

liquid steam gas

Collection of leakage Prevent air contact Cooling / heating Additional lubrication Prevent icing Vacuum operation Leakagecontroll

Mechanical sealsBasic PartsFeatures of SealfacesRotating facesRotating facesStationary facesStationary facesSecondary sealing elements0-rings: location and compressionSpringsTorque transmissionsFunction of a mechanical sealUnbalanced / balanced sealsUnbalanced sealsBalanced sealsHeat developement of a sealThe sealing gapThe sealing gapLeakageLeakage effecting parametersTypes of sealsSingle seal arrangement 1Single seal arrangement 2Single seal arrangement 3Seal arrangementsDouble acting seal arrangermentsTandem arrangementSeal materialsSeal face materialsBurgmann standard materialsDIN standard materialsSecondary seals materialsSecondary sealing elementsSprings and construction