Rubber seals are selected for a specific location and function, not by diameter alone. The sealing function, medium, temperature and pressure, connection geometry and installation method must be known. It is also necessary to determine whether the ordered component is a connection seal or the working sleeve of a pinch valve — a similar material does not mean the same function.
Rubber seals — what data should selection start with?
The first step is to identify the installation location. A seal between mating surfaces requires different information from a component that is in direct contact with the medium and changes shape while the equipment operates. The term “rubber seal” alone does not describe the geometry or loading method.
Include a drawing, the dimensions of the existing component and a photograph of the installation location with the enquiry. If a replacement is being selected, also provide the equipment designation and describe the reason for replacement. Copying only the dimension of the removed part may repeat the previous selection error.
Five groups of data required for seal selection
| Data group | What to provide | Why it is required |
|---|---|---|
| Component function | The installation location and the component’s task in the valve or fitting. | This distinguishes a connection seal from a moving or replaceable working component. |
| Medium | The exact name, composition or concentration and the presence of solid particles. | Material compatibility is assessed for the actual medium, not for a general industry name. |
| Operating conditions | Pressure, operating temperature and minimum, maximum and transient values. | The operating range of another rubber product must not be transferred to the seal. |
| Geometry | Dimensions, shape, seat or sealing face and mating surfaces. | A material compatible with the medium cannot compensate for incorrect geometry. |
| Installation and operation | Compression method, disassembly frequency, service access and the observed type of leakage. | These data help distinguish a selection problem from an installation or connection-condition problem. |
A seal vs a rubber pinch-valve sleeve
Metal-Gum’s current product page describes the rubber sleeve as the working component of a pinch valve that remains in direct contact with the medium. The valve shuts off the flow by externally pinching the sleeve; when opened, the sleeve returns to its full bore. A worn sleeve can be replaced without replacing the complete valve.
This function differs from sealing a connection. For its sleeves, Metal-Gum publishes NR, EPDM, NBR and SBR compounds and selection by medium, temperature, pressure and operating method. This information applies to pinch-valve sleeves and must not automatically be used as the parameters of any rubber seal.
When ordering a part, state the equipment name and the component’s role. The phrase “rubber for a valve” is too broad and may cause a working component to be confused with a connection seal.
What should be checked when seal service life is too short?
If leakage returns after replacement, do not immediately assume that the next part is defective. First compare the current operating conditions with the data used for the original selection.
- check whether the medium, its composition or concentration has changed;
- compare operating temperature and pressure with the values during start-up, flushing and shutdown;
- inspect the seat, sealing face and mating surfaces;
- confirm the dimensions and shape instead of relying only on the equipment designation;
- verify the compression method and installation sequence against the documentation for the connection;
- determine whether the replaced part is a seal or a working component subjected to cyclic deformation.
This list does not replace the valve manufacturer’s instructions. It organises the data that must be collected before another selection or technical consultation.
Checklist for a rubber-seal enquiry
- Name the equipment and the function of the component being replaced.
- Provide the medium, its composition, concentration and the presence of solid particles.
- State the pressure and the complete operating-temperature range.
- Include dimensions, a drawing or a clear photograph of the connection geometry.
- Describe the compression method and service access.
- If a failure occurred, describe the leakage location and the condition of the removed part.
- State whether a new seal or a pinch-valve sleeve is required.
Common mistakes
- selecting by dimension alone;
- transferring a material or operating range from another rubber component;
- providing a general medium name without composition or concentration;
- omitting transient temperature or pressure values;
- ordering “rubber for a valve” without identifying the function of the part;
- replacing the component again without checking the mating surfaces and installation method.
Frequently asked questions
Can a rubber seal be selected by dimension alone?
No. The dimension confirms only geometric fit. Selection also requires the component’s function, medium, temperature, pressure, compression method and the condition of the mating surfaces. A matching dimension does not confirm material compatibility or correct operation in the specific connection.
Is a rubber pinch-valve sleeve a seal?
These terms should not be used interchangeably. Metal-Gum describes the sleeve as a replaceable working component of the valve that contacts the medium and is pinched when the flow is shut off. A connection seal is selected for a different function and geometry, so sleeve data must not automatically be transferred to the seal.
Which data are most important when leakage keeps returning?
In addition to the medium, temperature and pressure, provide information about the leakage location, geometry, mating surfaces and installation method. Photographs of the removed component and installation location are useful. This allows the complete connection to be assessed instead of simply copying the previous dimension again.
Identify the component before sending an enquiry
If you need a valve working component, see the current Pinch valves and sleeves product page for both rubber sleeves and available Metal-Gum pinch valves.
If the enquiry concerns a rubber component that changes the direction of a pipeline, also read the guide to selecting rubber elbows and bends.
For a connection seal, send the Metal-Gum technical team the complete checklist data. This allows the function of the component to be confirmed before its execution is selected.
