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Flat gaskets made of rubber in NBR, EPDM, FKM & silicone. Find out all about applications, selection criteria and custom-made parts.
The selection of the right seal in water technology directly influences service life, operational reliability and maintenance effort. Depending on the area of application, the requirements for material, resistance and mechanical properties differ significantly. A well-founded selection reduces failures and secures stable systems in the long term.
In practice, it becomes clear that seals are often used under demanding conditions: fluctuating temperatures, changing pressure conditions and different media act on the material simultaneously. With an unsuitable selection, this combination quickly leads to leaks, material failure or increased maintenance effort.
Even at the planning stage, precise matching to the operating medium, temperature and pressure is worthwhile. For individual requirements, cut-to-size rubber and elastomers are suitable, precisely matched to the respective application.
Requirements for seals in water technology
Seals in water-carrying systems must remain permanently tight, even under changing loads. Typical requirements are:
- Resistance to water and additives
- Temperature resistance in cold and hot water
- Pressure stability in pipelines and plants
- Ageing resistance and low embrittlement
- Flexibility under movement and vibration
Particularly in water technology, several factors often act simultaneously, which makes the choice of material more demanding.
Materials in comparison
The choice of the right material decisively determines the performance of the seal.
| Material | Properties | Typical areas of application |
|---|---|---|
| EPDM | Very good water and weather resistance | Drinking water, outdoor installations |
| NBR | Good oil resistance, limited water resistance | Mixed systems |
| FKM | High temperature and chemical resistance | Industrial plants |
| PTFE | Very high chemical resistance | Aggressive media |
EPDM is regarded as the standard material in water technology, particularly in drinking water applications. Further details on properties and areas of application can be found under EPDM seals.
Influencing factors in selection
The selection of a seal is always based on the real operating conditions. Several factors are decisive and must be assessed in combination. An isolated consideration of individual parameters frequently leads to wrong decisions.
Temperature
Temperature has a direct influence on the material properties. In hot water applications, the thermal load increases permanently, as a result of which elastomers can change more quickly.
EPDM shows stable performance in the typical hot water range. At higher temperatures or strongly fluctuating conditions, materials such as FKM are used. It is important to take continuous and peak temperatures into account.
Pressure
Pressure conditions determine the mechanical load on the seal. In static applications such as flange connections, different forces act than in dynamic systems with movement.
The right Shore hardness, material thickness and geometry ensure that the seal remains dimensionally stable and seats evenly. Materials that are too soft can be displaced, materials that are too hard often seal inadequately.
Media
In addition to pure water, additives, chemicals or dirt particles play a major role. These can attack the material or change the surface.
A precise analysis of the medium is therefore essential. EPDM is suitable for many water applications, while PTFE or FKM tend to be used for chemically loaded media.
Selecting the right seal – step by step
- Define the medium: water, additives, chemicals
- Determine the temperature: take continuous and peak values into account
- Determine the pressure: static or dynamic
- Check the standards: drinking water approval required
- Select the material: EPDM, NBR, FKM or PTFE
- Define the geometry: shape, thickness, Shore hardness
- Choose the production method: standard or cut to size
Typical seal shapes in water technology
- Flat gaskets: standard in flange connections
- O-rings: compact and versatile
- Profile seals: for complex geometries
- Moulded parts: individually manufactured for specific applications
The choice of shape influences the sealing effect and the assembly effort.
Important technical characteristics
- Shore hardness: determines deformability and sealing behaviour
- Compression behaviour: behaviour under pressure load
- Recovery capability: ability to return to shape after unloading
- Ageing resistance: behaviour over long periods of use
These characteristics determine the long-term function of the seal.
Typical applications in water technology
Seals are used in different areas:
- Drinking water systems
- Wastewater plants
- Pump systems
- Pipelines
- Fittings and valves
Depending on the application, the requirements vary considerably.
Standards and approvals
For applications in water technology, particularly in the drinking water sector, clear legal and technical requirements apply. These concern both the materials used and their processing.
Materials must be approved for contact with drinking water and must not release any substances that affect water quality. Typical requirements concern migration, odour and taste neutrality as well as hygienic safety.
In addition, national and European regulations play a role in defining the suitability of materials. For operators and planners, this means planning certainty as well as a clear basis for material selection.
Certifications and tested materials secure use in sensitive areas and reduce risks in ongoing operation.
Selection aid
The following overview helps with classification:
| Application | Recommended material |
|---|---|
| Drinking water | EPDM |
| Wastewater | EPDM, NBR |
| Chemically loaded water | PTFE, FKM |
| Hot water | EPDM, FKM |
For precise requirements, individual matching and technical advice are recommended.
Installation and typical assembly errors
- incorrect preload
- contaminated sealing surfaces
- incorrect storage before installation
- unsuitable lubricants
Clean assembly considerably increases the service life.
Typical errors in selection
Errors in seal selection frequently lead to leaks or premature wear:
- Wrong material for the medium
- Insufficient temperature resistance
- Failure to take pressure conditions into account
- Standard solutions instead of precisely fitting cut pieces
A precise analysis before selection prevents later problems.
Practical examples
In practice, it becomes clear that standard solutions often work only in the short term. Particularly in plants with changing operating conditions, problems frequently occur when material and geometry are not precisely matched.
A typical example is pump systems in water treatment. Here, pressure fluctuations and temperature changes act on the seal simultaneously. Custom-made EPDM seals with adapted Shore hardness ensure a significantly longer service life in such cases.
In pipeline systems with chemically loaded water, too, the advantage of specialised materials becomes apparent. The use of PTFE or FKM reduces wear and prevents material degradation by aggressive components.
Individually manufactured seals increase the service life of plants and reduce maintenance intervals. Particularly in complex applications, tailor-made solutions offer clear economic advantages.
Enquiry and implementation
For specific applications, a project-related design is recommended, in which all relevant parameters are systematically recorded and assessed. These include medium, temperature range, pressure conditions as well as the installation situation and the desired service life.
On this basis, the suitable material is selected and the geometry, material thickness and Shore hardness are defined. Particularly in demanding applications, precision manufacturing offers clear advantages, since the seal can be adapted exactly to the existing components.
In the next step, it is checked whether standard solutions are sufficient or whether individual manufacturing makes sense. Especially in complex plants, special dimensions or increased requirements for resistance and service life, cutting to size leads to significantly more stable results in ongoing operation.
Through close coordination, typical problems can be avoided in advance. These include leaks, premature wear or unnecessary maintenance intervals.
Submit your requirements for a well-founded assessment and a solution that suits your application technically and economically.
Frequently asked questions about seals for water technology
Which seal is suitable for drinking water?
EPDM is frequently used for drinking water applications, since this material has a high water resistance and is available with corresponding approvals for many applications.
Which seal is suitable for hot water?
EPDM and FKM are primarily suitable for hot water. Which variant fits depends on the specific temperature range and the other operating conditions.
What influences the service life of a seal?
The service life is determined primarily by the medium, temperature, pressure, material quality and correct assembly. Changing loads and chemical influences also play a role.
Are custom-made seals worthwhile?
Yes, particularly for special dimensions, special installation situations or demanding operating conditions. Custom-made seals improve fit accuracy, service life and operational reliability.
EPDM or NBR for water?
EPDM is very well suited to many classic water applications. NBR tends to be used when oil or other media also play a role. The selection always depends on the actual case of use.
Which seal is suitable for pressure lines?
In pressure lines, material, geometry, material thickness and Shore hardness must be matched exactly to the pressure conditions so that the seal remains dimensionally stable and tight in the long term.
Our rubber sheets
For industry and trade, we offer a wide variety of rubber sheets.
SBR rubber sheet
Our high-quality SBR rubber sheet (styrene-butadiene rubber) is the solution for numerous industrial and commercial applications. This rubber sheet is manufactured from first-class styrene-butadiene rubber and is characterised by its outstanding physical properties.
EPDM rubber sheet
Discover the versatility and reliability of our EPDM rubber sheet, which is manufactured from ethylene propylene diene monomer (EPDM). This high-quality elastomer solution has been specially developed to meet the most demanding industrial and commercial applications.
NBR rubber sheet
The NBR rubber sheet is a high-quality industrial product that has been specially developed for applications requiring excellent resistance to oils, greases and various chemicals.
Viton rubber sheet
The Viton rubber sheet is a high-quality technical product that is used for a wide range of industrial applications. Manufactured from fluoro rubber (FKM), it offers outstanding properties that make it the ideal choice for extreme conditions.
FKM rubber sheet
The FKM rubber sheet is a high-quality technical product that is ideal for use in demanding industrial applications. Made from fluoro rubber (FKM), it is distinguished by a wide range of outstanding properties that make it the optimum choice for extreme operating conditions.
Silicone rubber sheet
The silicone rubber sheet is a first-class technical product that has been specially developed for applications placing high demands on temperature resistance and flexibility.
PUR rubber sheet
The PUR rubber sheet, made from high-quality polyurethane, is a technically advanced product that has been developed for applications placing the highest demands on abrasion resistance and mechanical load capacity.
Neoprene rubber sheet
The neoprene rubber sheet, manufactured from high-quality chloroprene rubber (CR), is a versatile technical product that is ideal for a wide range of industrial and commercial applications.
