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Carbon and Graphitefor Mechanical Seals

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Material Grade Recommendations forMechanical Seals Applications

average loads(typically< 10 MPa x m/s)

Highest load(typically> 10 MPa x m/s)

EK 2100synthetic resin impregnatedcarbon graphite

EK 2230pressed-to-size carbongraphite synthetic resinimpregnatedRIDURID V 1774carbon- and graphite-

filled synthetic resin(pxv 5 MPa x m/s)

EK 3105 antimonyimpregnated carbon

EK 3235 antimony im-pregnated carbon graphite

EK 2239 pressed-to-sizecarbon graphite all car-bon (acidic to alkaline

medium, temperature upto 400 C)

EK 2200 syntheticresin impregnated carbon

EK 3205 antimonyimpregnated carbongraphite

EK 2240 syntheticresin impregnatedcarbon graphite

EK 3245 syntheticresin impregnatedcarbon graphite

Application examplesTemperature Manufacture Material*

standard mechanical seals,e. g. in mechanical enginee-ring and for chemical pumps

automotive cooling waterpumps, household appliances

oil burner pumps

standard mechanical seals,e. g. in mechanical enginee-ring and for chemical pumps

process seals, fuel pumps,cooling compressors

dishwasher pumps, automo-tive cooling water pumps

mechanical seals, e. g. forfeed water pumps in powerstations

mechanical seals; e. g. forcompressors

mechanical seals;e. g. for agitators

mechanical seals;e. g. for autoclaves

up to 200 Cfor use with pre-dominantly neutralto acidic medium

up to 550 C(in oxidisedatmosphere up to400 C)for use with pre-dominantly neutralto alkaline medium

up to 200 C forpredominantlyneutral to acidicmedium

up to 550 C(in oxidising atmos-phere up to 400 C)for predominantlyneutral to alkalinemedium

up to 200 C

up to 550 C(in oxidising atmos-phere up to 400 C)

small-sized andunit production upto 205 mm

high volumeproduction tool-dependent up to 60 mm

small-sized andunit production upto 205 mm

high volumeproduction tool-dependent up to 60 mm

standard dimen-sions up to 550 mm

standard dimensions

up to 550 mm

* Proof of gas tightness available on request for all materials.Certificates for use in the food industry are available.

Dry running

Wet running

Application examplesTemperature Manufacture Material*

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Carbon and Graphite by SGL CARBON

Applications

Carbon and graphite materials

are used in mechanical seals in

cases where gases or liquids

with low hydrodynamic

lubricating action have to be

sealed.

Fields of application

fuel pumps

chemical pumps

process pumps in refineries

seals for agitators and auto-

claves

cold and hot water pumps

pumps for household and

garden appliances

automobile cooling water

pumps

heat-removal loop pumps in

nuclear power stations

pumps for the beverages

industry

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Friction depends on

surface finish of the mating

surfaces

rubbing speed

specific loading

type and quantity of lubri-

cating medium

Wear rates as a function of thecounterface material, using

EK 2230 and EK 3235 at a

steady rubbing speed of

4.4 m/s and steady medium

pressure of 10 bar for differ-

ent counterface materials

(chromium cast, aluminium

oxide and silicon carbide).

Medium: demineralized water

Friction

It is difficult to give expected

wear figures as in practise

many factors have to be

considered, for example:

mating materials

rubbing speed loading

surface finish of mating

surfaces

presence of solid impurities

in the medium being sealed

operating conditions

Service life

grey cast iron

chromium cast

chrome steel

aluminium oxide

tungsten carbide

silicon carbide

carbon

Preferred counter-face materials

Tribological Behaviour

The following coefficients of friction ()

can be assumed as a guide:

Wet running: = 0.01 - 0.05

Mixed running: = 0.05 - 0.10

D ry r unning: = 0.1 - 0.25

Wear rates as a function of the

rubbing speed against carbide

materials, taking as examples

EK 2200 () and EK 3205

(--) at a steady rubbing

speed of 9 m/ s and increasingload. Medium: demineralised

water.

Wear (m/100 h)

Wear (m/h)

specific loading (N/mm2)

0 2 4 6 8 10 12

0 2 4 6 8 10 12

TUNGSTEN CARBIDE

Wear (m/h)

specific loading (N/mm2)

SILICON CARBIDE

Cr cast Al oxide Si carbide

10

1

0.1

0.01

10

1

0.1

0.01

EK 2230 EK 3235 EK 2230 EK 3235 EK 2230 EK 3235

1009080706050403020100

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Can be supplied with a

variety of surface finish.

If the application permits,

bearing in mind economy

and in view of manufactur-

ing costs, storage and pack-

aging as well as handling in

subsequent assembly, the

following maximum surface

finish criteria should beconsidered.

Manufacture

All of the above forming

processes, offer significant

savings when the special featu-

res of carbon and graphite

materials are considered at the

design phase. Take advantage

of SGL CARBON s technical

support at the design phase.

Surface flatness of rubbing faces*

1 light band = 0.297 m, * measured using interference test equipment

Diameter in mm

< 75

75150

150225

> 225

Number of light bands

2

3

5

8

pressed-to-size carbon graphitemechanical seals

RIDURID and graphite-filledplastic mechanical seals

Carbon graphite mechanical

seals

beginning at5,000 units

beginning at10,000 units

1 5,000 units

TolerancesMechanical seals Manufacture Economic batch sizes

tolerances + 0.5 % ofthe nominal size simpleto average complexgeometries

tolerances from IT 9 areachievable

possible without any limita-tion on the geometry

tolerance from IT 6 are are

achieved

tool-dependent manufacturefor large-batch productionup to 60 x 25 mmstandard

material-dependent manu-facture for large batchesusing the familiar process ofplastics forming (injectionmoulding, hot pressing)

machining of small quantities

up to 550 mm

Tolerances and dimensions according to manufacturing process and typical batch sizes

Good surface flatness Poor surface flatness

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Graphite SpecialtiesBusiness Unit

SGL CARBON GmbHWerk Ringsdorff

Drachenburgstrae 1

D- 53170 Bonn

Phone: +49 (228) 841-394

F ax: +49 (228) 841-456

Intern et: www.sglcarbon .com

This information is based on ou r pre-

sent state of knowledge and is intend-

ed to pr ovide general notes on our

products and their uses. It should not

therefore be constru ed as guaranteeing

specific properties of the prod ucts

described or their suitability for a

particular application. A ny existing

industrial property rights must be

observed. The quality of our products

is guaranteed under our General

Co nditions of Sale.

02 02/ 3E Printed in Germany