Description

 O-ring most widely use as sealing element. o-rings offer to the designers an ef- ficient and economically advantageous sealing element for a wide range of various static and/or dynamic applications.

cost-effective way of production and easy us- ability made from the o-rings the most expanded sealing element. the wide range of elastomer materials for standard and special applications enables usage of the o-rings for sealing of practically all liquid and gaseous media.

the o-rings are vulcanised in dies and are characterised by their ring shape with round cross-section. the size of the o-ring is defined by internal diameter  Ød and by cross- section H (thickness). please see picture below.

the cross-sections from 0.35 to 15 mm and the internal diameters  up to 5,000 mm are available.

Application

 

 

 

Function

the o-ring is a double-acting  sealing element. the sealing effect is achieved by deformation of the round profile of the o-ring. the size of the deformation is determined by the groove depth t. the deformation,  which is sometimes  called also depression  or pre-tension, acts in radial or axial direction and provides the o-ring with the initial sealing ability. under pressure, the o-ring behaves similarly as a liquid with high surface tension. the pressure is uniformly transferred in all directions. the force raised by the initial deformation of the o-ring is added  to the force raised by the pressure in the system and they together create the resulting sealing force.

 

Advantages

compared with other sealing elements the o-ring features many advantages:

– it inexpensive and enables cost-effective solutions;

– it may be used as the single and double acting solutions due to its symmetrical diameter;

– simple groove decreases costs for design and production;

– compact shape enables lower built-up;

– simple and reliable installation, incorrect assembly is not possible;

 

Usability area

–usability for wide range of static and dynamic sealing applications;

– wide choice of mixtures for compatibility with most of the liquids.

the o-rings are used primary as the sealing elements and as activating elements for combined sealants and oil scraper rings.

the o-rings are mostly used as the static seal

– with radial compression, e.g. for cocks, valves, hydraulic cylinders etc.

– with axial compression, e.g. flange joints, lids, hydraulic elements etc.

for dynamic applications, the o-rings are recommended only for mild operating conditions. their life-time depends above all on existence

of the lubricating film, system pressure, temperature, size of the sealing gap, speed/type of media, and on the surface quality of areas of

the metal components.

very generally  it is possible to recommend  the limit values of 100 bar or 0.3 m/s, respectively the product p x v ≤ 2 [MPa,  m/s].

in case the larger gaps are needed, it is always necessary to use the back-up ring according  to the pressure application  from one / both

ends of the o-ring. for rotational movement, the o-rings are generally not suitable, as the lubricant supply to the sealing surfaces is imper-

fect. during the movement, increase friction an occur, local overheating and quicker wearing.

if exceptionally other sealing element may not be used, it is more suitable to assemble the o-ring on the stationary part. then the centrifu-

gal force does not affect on the o-ring. more suitable types of the sealants are available for most of the rotation applications.

 

overview of materials

 

polyacrylate rubber (ACM)

the excellent characteristic  of the acrylate rubber is its excellent resistance against high temperatures and hot oil. ACM is resistant against engine oils with modern additives, gearbox oils, lubricating greases etc. besides this, it features the high oxidation and ozone resistance of the saturated polymer chain. the temperature range is from –40 °C to +200 °C.

 

acrylonitrile-butadiene rubber (Nitrile rubber) (NBR)

the NBR rubber is resistant above all against effecting of oils, mainly hydraulic oils, lubricating oils, petrol and other aliphatic hydrocarbons, acids and bases. good physical properties such as high durability, abrasion resistance and temperature resistance (-25 °C - +125 °C) ensure to this type of rubber wide area of usage.

 

hydrogenated acrylonitrile-butadiene rubber (HNBR)

the sealants from the HNBR rubber feature excellent spectrum of characteristics. the high resistance against additive technical oils, low liquid

/ gas  permeability, good flexibility at coolness to –40 °C, good resistance against ozone and high abrasion resistance. the HNBR are resistant

against temperature up to +145 °C.

 

chloroprene rubber (CR)

chemical and physical characteristics of the CR rubber are similar to the ones of the NBR rubber. however, the resistance against mineral oils is somewhat lower, but the resistance against the ageing, ozone, acids and alkalis are excellent. the application temperature range is from –40 °C to +120 °C.

 

butyl rubber(IIR)

sealants from the material feature very low permeability of gasses, high resistance against oxide and ozone, good electric properties and excel- lent resistance against animal and vegetable oils/greases. this material is not suitable for applications  with mineral oils. the application tempera- ture range is from –40 °C to +140 °C.

 

natural rubber (NR)

the natural rubber is highly elastic material with excellent physical properties. in spite of wide range of synthetic rubbers with special character- istics, the natural rubber is still extensively  used. the temperature range is from –45 °C to +100 °C.

 

chlorsulphonated polyethylene rubber (CSM)

CSM features excellent resistance against ozone, acids and alkalis, is resistant against ageing, and has good mechanical and physical proper- ties. the mineral oils may cause the swelling, whose size depends on the application temperature and type of hydrocarbons components. the temperature range is from –25 °C to +135 °C.

 

ehtylene propylene diene rubber (EPDM)

the usage area of the rubber is in case, where the high resistance against hot water and steam is required from the used sealant. besides this, the EPDM  is very resistant against ageing and ozone. the resistance against freezing may be treated as good compared with usual types of synthetic rubbers. the behaviour under influence of oils, lubricating greases and solvents approximately corresponds to the properties of the butadiensty- rene rubber (SBR). the resistance against chemicals, even oxidizing, is very good. the temperature range is from –40 °C to +140 °C.

 

fluorocarbon rubber – viton® (FPM, FKM)

extraordinary resistance against mineral oils, aliphatic and aromatic hydrocarbons and chlorinated hydrocarbons, concentrated and rarefied ac- ids and mild alkali substances. the excellent temperature resistance up to +200 °C and resistance against low temperatures to – 30 °C according to used types, high mechanical values and excellent resistance against ageing classify the FPM rubber high above usual synthetic rubbers.

 

fluorocarbon rubber viton ® extreme™

excellent resistance of the fluoroelastomer against the chemicals is yet superseded  by the viton® extreme™ material. the modified polymer struc- ture significantly decreases the swelling in solvents and high alkali medias, the resistance against temperatures and flexibility under low tem- peratures  are preserved  and range from –15 °C to +200 °C. this material is used in areas, where the aggressive chemicals require high resistance.

 

polytetrafluoroethylene teflon® (PTFE)

beside general resistance, it features the resistance against alkali metals and gaseous fluorine under pressure. good sliding characteristics, low wearing, heat resistance from –200 °C to +260 °C. regarding  the PTFE hardness of cca 95° Dhore, the assembly into open grooves is recommend- ed.

 

tetrafluoroethylenepropylene rubber (TFE/P) aflas®

aflas is a special rubber and belongs to the newer generation of fluoroelastomers. the sealing rings from aflas feature extraordinary resistance against whole range of specific medias and chemicals, such as hot water, water steam, acids, alkalis, ammoniac, bleaching agents, sulphur gases and oils and amines, especially against medias with additives, containing amines and corrosion inhibitors, additive engine and gearbox oils, break liquid and medias with oxidants. the application temperatures are similarly as for fluoroelastomers from –20 °C to +200 °C. mostability from - 200 °C bis +260 °C. Regarding hardness PTFE c. 95° shore advises assembly  bis open grooves.

 

fluorsilicone rubber (FVMQ)

the fluorsilicon rubber features besides typical properties of normal silicon rubber also the substantially improved resistance against the oils, fuels and solvents. this characteristic applies above all for aromatic and chlorinated hydrocarbons and alcohols. the application ranges are therefore determined above all for requirement for resistance at the wide temperature range from –60 °C to +200 °C by simultaneous affecting of aggressive medias as e.g. petrol, alcohol mixtures, aromatic oils and number of chlorinated solvents.

 

silicon rubber (VMQ)

the application  area of the rubber is based on its excellent heat resistance (-55 °C to +200 °C), however it cannot be transmitted to hot water or steam. even if the silicon rubber resistance against oils is approximately at the level of NBR, the good physically mechanical properties of the material are not achieved.

 

polyurethane rubber (AU)

the sealants from the polyurethane rubber feature above all high resistance. the sealing rings from polyurethane feature high mechanical values, such as breaking / abrasion resistance, high reflection elasticity and good properties for sealing of gases. the resistance against fuels and against number of technically usual oils, mainly against the oils with high content of aromatics, is excellent. the sealants from the polyurethane rubber have with regard to good heat resistance (up to +125 °C) and good flexibility under low temperatures (to –30 °C) also the excellent resistance against oxide and ozone and high life-time.

 

medium

NR

IIR

EPDM

NBR

HNBR

CR

CSM

AU

ACM

MVQ

FVMQ

TFE/P

FKM

RP-1 (Mil-R-25576C)

D

D

D

A

A

B

B

A

A

D

A

E

A

S

 

 

 

 

 

 

 

 

 

 

 

 

 

Salicylous Acid

A

A

A

B

B

A

E

E

E

E

A

E

A

Salt Water

A

A

A

A

A

B

A

B

D

A

A

E

A

Sewage (as per DIN 4045)

B

B

B

A

A

B

A

D

D

B

A

E

A

Silage

D

B

B

A

A

D

D

A

A

B

A

E

A

Silicate Ester

D

D

D

B

B

A

A

A

E

D

A

E

A

Silicone Grease

A

A

A

A

A

A

A

A

A

C

A

E

A

Silicone Oil

A

A

A

A

A

A

A

A

A

C

A

E

A

Silver Nitrate

A

A

A

B

B

A

A

A

A

A

A

E

A

Sizing Agent (DIN 16920)

B

B

A

A

E

A

A

A

E

A

A

E

A

Skydrol 500

D

B

A

D

D

D

D

D

D

C

C

B

D

Skydrol 7000

D

A

A

D

D

D

D

D

D

C

C

E

B

Soap Solution

B

A

A

A

A

B

A

C

D

A

A

E

A

Sodium Acetate

A

A

A

B

B

B

A

D

D

D

D

E

D

Sodium Borate Solution

A

A

A

A

A

A

A

E

E

A

A

A

A

Sodium Carbonate, crystallic, anhydrous

A

A

A

A

A

A

A

E

E

A

A

E

A

Sodium Cyanide Solution

A

A

A

A

A

A

A

E

E

A

A

E

A

Sodium Hydroxide Solution

A

A

A

B

B

A

A

D

C

B

B

A

B

Sodium Hypochlorite Solution

D

B

B

B

B

A

A

D

D

B

B

A

A

Sodium Chloride Solution (Salt)

A

A

A

A

A

A

A

A

E

A

A

A

A

Sodium Nitrate Solution

B

A

A

B

E

B

A

E

E

D

E

A

A

Sodium Peroxide Liquid

B

A

A

B

B

B

B

D

D

D

A

E

B

Sodium Phosphate Solution

A

A

A

A

A

B

A

A

A

D

E

A

A

Sodium Silicate Solution

A

A

A

A

A

A

A

E

E

E

E

A

A

Sodium Thiosulphate Solution

B

A

A

B

E

A

A

A

D

A

A

E

A

Solution for chromating

D

B

B

D

D

D

D

D

D

B

B

E

A

Solvent - Stoddard

D

D

D

A

A

B

D

A

A

D

A

E

A

Soy Bean Oil

D

C

C

A

A

B

C

B

A

A

A

E

A

Spirit

A

A

A

A

A

A

A

D

D

A

A

E

A

Stack Gas

D

D

D

D

D

D

D

D

D

A

B

E

A

Stack Oil

D

D

D

A

A

D

D

B

A

B

A

E

A

Stannic Chloride Solution

A

A

A

A

A

B

A

E

E

B

A

E

A

Stannous Chloride Solution

A

A

A

A

A

A

A

E

E

B

A

E

A

Stearic Acid

B

B

B

B

B

B

B

A

E

B

E

A

A

Sucrose Sap

A

A

A

A

B

B

B

D

D

A

A

E

A

Sulphate Slop, green

B

A

A

B

B

B

B

A

B

A

B

E

A

Sulphur

D

A

A

D

D

A

A

E

D

C

A

E

A

Sulphur Dioxide (damp)

D

A

A

D

D

B

A

E

D

B

B

E

B

Sulphur Dioxide (dry)

B

B

A

D

D

D

B

E

D

B

B

B

B

Sulphur Dioxide Liquid

D

B

A

D

D

D

D

E

D

B

B

E

B

Sulphur Hexafluoride

D

A

A

B

B

A

B

E

D

B

B

E

A

Sulphur Chloride

D

D

D

C

D

C

B

E

D

C

A

E

A

Sulphur Trioxide

B

B

B

D

D

D

D

E

D

B

B

E

A

Sulphuric Acid (20% Oleum)

D

D

D

D

B

D

D

D

D

D

D

A

A

Sulphuric Acid, concentrated

D

D

C

D

E

D

A

D

D

D

D

A

A

Sulphuric Acid, diluted (Battery Acid)

C

B

B

C

E

B

A

C

B

D

C

A

A

Sulphuric Acid, diluted (Battery Acid)

C

B

B

C

E

B

A

C

B

D

C

A

A

Sulphurous Acid

B

B

B

B

B

B

A

C

D

D

E

E

C

Events