Description

VM Pneumatic Pinch Valve for Powder Conveying

The VM Pneumatic Pinch Valve provides pneumatically operated shut-off control for pipelines handling powders, granules, dust and other compatible materials.

Instead of using a rigid disc or gate to close the passage, the valve compresses a flexible rubber sleeve. With the sleeve released, material can pass through its internal opening. Compressed air applied around the sleeve causes it to deform inward and restrict the flow path.

The VM design combines an aluminum alloy housing, a replaceable sleeve and a pneumatic control connection. Threaded and flanged configurations are available within the nominal size range of 13–200 mm.

It is particularly suited to pneumatic conveying installations where the material passage, closure pressure and sleeve compatibility are important selection factors.

Technical Specifications

The operating pressure and temperature limits apply to the specified reference configuration. Sleeve material, actual process temperature, ambient conditions and connection dimensions should be confirmed for the selected assembly.

VM Pneumatic Pinch Valve Dimensions

The VM series includes different connection arrangements according to nominal bore. The dimensional information below separates smaller threaded configurations from larger flanged valve bodies.

VM013–VM032 Threaded Dimensions

VM040–VM0200 Flanged Dimensions

Dimensional Notes

• All linear dimensions are in millimeters unless otherwise stated.

• G identifies the pneumatic control-air connection.

• M identifies the pipe connection thread where applicable.

• D identifies the flange fixing thread, while Holes indicates the number of fixing positions.

• The remaining letters correspond to the dimensional drawing.

• For VM050, the J dimension must be checked against the approved installation drawing because different reference dimensions exist.

For replacement installations, the nominal bore, overall dimensions, flange arrangement and control-air connection should be compared before ordering.

Flexible Sleeve and Pneumatic Operation

The flexible sleeve is both the material-contact passage and the valve’s closing element.

During normal air-released operation, the sleeve remains open. Material travels through its internal bore without a rigid closing disc positioned across the flow path.

To close the valve, compressed air enters the chamber between the housing and the sleeve. The pressure causes the sleeve to contract until the passage is shut.

The sleeve returns toward its open shape when the closing pressure is released.

Because the conveyed material contacts the sleeve, selecting the rubber compound is important. Abrasive particles, chemical exposure, temperature and operating frequency can affect sleeve suitability and wear.

The valve should therefore be selected as a complete housing-and-sleeve assembly rather than by nominal diameter alone.

Pipeline Pressure and Closing Air Requirements

The VM valve uses two different pressure conditions.

Pipeline pressure (Pi) is the pressure inside the conveying passage.

Control pressure (Pc) is the compressed-air pressure applied around the sleeve to close the valve.

For the standard reference closing arrangement:

The closing-pressure relationship must remain within the permitted control-pressure limit. Different sleeve configurations may require different closing-pressure settings.

The pneumatic supply should be regulated to the required pressure for the actual operating condition. The air-control circuit should also allow the sleeve chamber to exhaust when the valve is commanded to open.

The 6 bar control-pressure limit must not be interpreted as a 6 bar rating for the conveying pipeline.

For automated systems, the compressed-air supply, solenoid valve, regulator and required valve state during loss of air should be considered together.

Sleeve Material and Replacement

The sleeve is a serviceable component rather than a permanent part of the metal housing.

As the main material-contact surface, it is exposed to the conveyed product while repeatedly deforming during valve operation.

Its condition should be inspected for:

• Surface abrasion or localized wear

• Cracks, cuts or visible damage

• Permanent deformation

• Deterioration affecting sleeve recovery

• Damage around the sleeve mounting areas

Sleeve replacement should be based on the observed condition and actual duty rather than a fixed service-life claim.

Before maintenance, the conveying line must be isolated, depressurized and made safe for disassembly. The sleeve should be replaced with a correctly matched component and the assembled valve checked before returning it to operation.

Where sleeve material differs from the original configuration, compatibility with the conveyed product and closure requirements should be confirmed.

Pneumatic Conveying Applications

The VM Pneumatic Pinch Valve is intended for compatible material-transfer pipelines that require pneumatically controlled isolation.

Typical applications include:

• Cement and fly ash conveying pipelines

• Mineral powder transfer equipment

• Plastic granule conveying systems

• Dust and dry bulk material handling

• Chemical powder processing

• Building material production systems

In these applications, the valve is installed in the conveying line rather than acting as a conventional rotating-disc valve at the bottom of a silo.

For installations that require a compact shut-off arrangement directly at a silo outlet, a VFS Butterfly Valve may be considered according to the connection and operating requirements.

The pinch valve’s installation should account for pipeline alignment, available maintenance space and access to the control-air connection.

The valve body should not be used to compensate for misaligned piping or excessive unsupported loads.

Selection and Replacement Information

A VM Pneumatic Pinch Valve should be selected using the conveying conditions and the existing pipeline interface.

For accurate selection, the following information is useful:

For replacement work, the air-connection position and overall installation dimensions should be checked together with the pipe connection.

TONGJINJIN supplies VM Pneumatic Pinch Valves for powder conveying and bulk material handling systems.

Valve size, connection arrangement and sleeve requirements can be matched according to the installation. OEM and ODM supply is available for equipment manufacturers, conveying system suppliers, distributors and maintenance projects.

Frequently Asked Questions About VM Pneumatic Pinch Valves

Can the VM Pneumatic Pinch Valve operate in a pipeline with 6 bar internal pressure?

Not under the stated reference pipeline-pressure limit of 3.5 bar. The 6 bar value is the maximum control-air pressure used to compress the sleeve, not the allowable internal conveying pressure.

What happens if the compressed-air supply is lost?

In the standard air-to-close arrangement, releasing the pressure around the sleeve allows it to relax toward the open position. However, actual valve behavior can be influenced by residual pressure, material conditions and the pneumatic control circuit. The valve should not be assumed to provide fail-closed isolation during loss of air.

Can the sleeve close while powder or granules remain in the pipeline?

It may be possible with compatible materials, but closure depends on particle characteristics, material concentration and the available closing pressure. Large, hard particles or accumulated material may interfere with complete sleeve closure.

Can the VM Pinch Valve handle abrasive powders?

It can be considered for abrasive-material service when an appropriate sleeve compound is selected. Material hardness, particle size, conveying speed and operating frequency should be reviewed because these conditions influence sleeve wear.

Can the rubber sleeve be replaced separately?

Yes, the sleeve is a replaceable component. The valve must be isolated and depressurized before maintenance. The procedure and required disassembly depend on the selected valve construction and installation.

Why might the valve fail to close even when compressed air is available?

Check whether the control pressure is sufficient relative to the pipeline pressure. The regulator, air supply, control valve, connecting lines and sleeve condition should also be inspected. A control-pressure reading alone does not confirm that the sleeve has completed closure.

What should be checked before replacing an existing VM Pinch Valve?

Confirm the nominal bore, overall dimensions, pipe connection, mounting arrangement and pneumatic control-air connection. The sleeve material and operating-pressure requirements should also match the application. For direct replacement, use the approved dimensional drawing rather than the nominal size alone.