Technical guide
Pneumatic pinch valves
Pneumatic pinch valves are industrial valves intended primarily for shutting off the flow of liquid, semi-liquid media and media containing solid particles. Their operation is based on pinching a flexible rubber sleeve by a mechanism located outside the medium stream.
This solution is used, among other applications, in installations transporting slurries, pulps, wastewater, suspensions and other media containing abrasive particles or contaminants. The rubber sleeve is the working component in direct contact with the medium. Its material and execution must be selected for the type of medium, temperature, pressure and operating conditions of the installation.
How does a pneumatic pinch valve work?
In the open position, the rubber sleeve remains open, allowing the medium to flow through the valve. In the pneumatic version, the pinching mechanism is moved by an actuator using compressed air. The closing mechanism is located outside the direct medium stream, which makes the design useful in installations where the medium contains solid particles, deposits or substances that may cause wear of conventional valve components.
Depending on the design, the valve may have manual, electric or pneumatic actuation. A pneumatic version is worth considering in installations requiring remote control or integration with an automatic process control system. The possibility of such operation, available supply pressure, control method and operating frequency must be confirmed for the specific execution.
Which media are pinch valves used for?
Pinch valves are used primarily where the medium may interfere with conventional valves whose closing elements are located directly in the flow. Typical applications include:
- slurries and pulps,
- wastewater and sludge,
- suspensions,
- media containing solid particles,
- abrasive materials,
- bulk and dusty materials,
- aggregates and other industrial media.
Pinch valves are used, among other applications, in mining, cement plants, wastewater management and industrial installations. The industry alone does not determine whether a particular valve can be used. Selection must take the actual properties of the medium and process conditions into account.
Can a pinch valve be used to regulate flow?
Pinch valves can be used not only to shut off flow but, in suitable executions, also to restrict or regulate it. However, not every model and valve configuration will be suitable for control service.
The suitability of a specific execution for throttling must be confirmed based on the valve parameters, sleeve and process conditions. If the valve is to operate as a control element, this function must be taken into account at the selection stage.
Rubber sleeve in a pinch valve
The rubber sleeve is the working component of the valve. It is responsible for shutting off the flow and separates the medium from the pinching mechanism. Available variants include drilled, undrilled and conical sleeves, as well as NR, EPDM, NBR and SBR compounds.
Sleeve material selection should take into account primarily the type of medium, its temperature, pressure, solid-particle content and the valve operating conditions. The sleeve is a replaceable component, so its wear does not mean that the entire valve body must be replaced. Before ordering, however, the type, dimensions and compatibility of the sleeve with the specific valve execution must be confirmed. Until the dedicated English selection page is published, available sleeve executions can be checked on the pinch valves and sleeves product page.
How do you select a pneumatic pinch valve?
- Medium – provide its name, composition, concentration and information about solid particles and abrasive properties.
- Operating pressure – include any temporary peak values.
- Operating temperature – provide the possible minimum and maximum values.
- Nominal diameter – provide the DN and required flow cross-section.
- Connections – specify their type and installation requirements.
- Valve function – specify whether the valve is to shut off the flow or, in a suitable execution, also regulate it.
- Control method – for a pneumatic execution, provide the parameters of the available air supply and the required control method.
- Operating conditions – specify cycle frequency, operating pattern and installation conditions.
- Sleeve requirements – provide the material, design, identification of the existing component or the need for a special execution.
Based on this information, the appropriate valve model, sleeve material and execution, and actuator configuration can be selected. The final execution should be confirmed by the technical team after analysing the operating conditions.
What information should be provided with an enquiry?
The more complete the installation data, the easier it is to confirm the appropriate execution.
| Area | What to provide | What it helps determine |
|---|---|---|
| Medium | type, composition, concentration and solid particles | sleeve compound and design |
| Pressure | operating pressure, maximum pressure and temporary peak values | permissible valve execution |
| Temperature | operating, minimum and maximum temperature | sleeve material and execution |
| Function | shut-off or regulation | operating and control method |
| Diameter | DN and required flow cross-section | valve model |
| Connections | type and dimensions | connection and installation method |
| Pneumatics | available supply pressure and control method | actuator and accessory configuration |
| Operation | number of cycles and operating frequency | operating requirements |
| Sleeve | material, type or identification of the existing sleeve | part compatibility with the valve and medium |
| Installation | available space and installation method | dimensions and service access |
When replacing an existing valve or sleeve, photographs, manufacturer markings, dimensions and technical documentation are also helpful.
Metal-Gum pinch valves
The Metal-Gum range includes different pinch valve executions, including the following series:
The individual models differ in design and in the range of available executions. Parameters of one model must therefore not be automatically applied to the others. For a specific installation, the appropriate model, sleeve and configuration should be selected based on the process parameters and the documentation for the specific execution.
See also
Frequently asked questions
Is a pinch valve suitable for media containing solid particles?
Yes. Pinch valves are used, among other applications, for media containing solid particles, slurries, pulps, sludge and abrasive materials. The appropriate execution must be selected for the type, size and concentration of the particles and the other process parameters.
Can the rubber sleeve be replaced?
Yes. The sleeve is a replaceable component. Before ordering, however, its type, dimensions, material and compatibility with the specific valve must be confirmed.
How should the sleeve material be selected?
The material should be selected primarily for the medium, temperature, pressure and operating conditions. Material tables are indicative, so the name of the medium alone is not always sufficient to determine the appropriate compound. Material compatibility should be confirmed by the technical team.
Can a pinch valve be controlled automatically?
Whether a pneumatic execution can be integrated with an automatic control system depends on the configuration of the specific valve and actuator. Selection should specify the available supply, control method, required operating mode and operating frequency.
Selecting a Metal-Gum pinch valve
If you need to select a pinch valve for a specific installation, provide information about the medium, pressure, temperature, DN, connections and required control method. Based on this information, the Metal-Gum technical team can verify the appropriate model, sleeve and configuration for the installation.