PREMAFLEX pinch valves – robust and reliable

Mr. Wolfgang Körber
Sales / Engineering
wolfgang.koerber@prema-service.com

Tel: +49 6172 6778-53

PREMAFLEX pinch valves are pneumatic shut-off devices for liquid, viscous, granular, contaminated, fibrous and aggressive substances. Our pinch valves have proven themselves over many years in a wide variety of industries. They are reliable, robust, inexpensive and available in a wide range of nominal widths. In addition, we offer all valve components in different material versions, in order to offer you, the customer, the widest possible range of applications.

PREMAFLEX pinch valves are used in the pneumatic transport of bulk materials of all kinds and are frequently used in the food and pharmaceutical industries as well as in the plastics and chemical industries. Likewise, the pneumatic shut-off devices are used in environmental technology, wastewater treatment, plant engineering, construction and mining. PREMAFLEX pinch valves serve to seal, shut off, regulate and meter various materials and raw materials.

By applying compressed air or liquid via the control connection of the PREMAFLEX pinch valve housings, a special, highly elastic rubber sleeve is compressed. The rubber sleeve closes flush to the central axis and, even with solid inclusions, locks the product flow completely tight. The function continues working, even at high switching frequencies, thanks to the highly elastic rubber sleeve. After the control medium is switched off, the rubber boot opens on its own due to the high rebound resilience and releases the nominal diameter cross section again. The medium pressure also supports the opening process but is not strictly necessary.

How PREMAFLEX pinch valves work:

ABOUT PINCH VALVES

Is it possible to use a pneumatically operated pinch valve with vacuum?

Pneumatically operated pinch valves can certainly be used with low vacuum. They are considered vacuum-tight up to a vacuum of 100 mbar.

Is it possible to control a pneumatically operated pinch valve with liquid (e.g. water)?

Pneumatically operated pinch valves can be controlled with gas and air as well as with liquid mediums. Safe operation of the pinch valve is therefore independent of the control medium. A sufficiently large differential pressure of 2 bar is required, however, to ensure the sleeve closes in the proper manner (lip-shaped). In addition to water, other, non-viscous and clean liquids are allowed.

What should I look for when selecting a pinch valve if my medium is very abrasive?

Pneumatically operated pinch valves are characterized by short closing and opening times. This is what protects the valve from the influence of abrasive media. Therefore, be sure to install the magnetic valve directly on the pinch valve and install a quick-release valve.

According to what standard or DIN are the pneumatically operated pinch valves manufactured?

A pneumatically operated pinch valve is subject to the Pressure Equipment Directive PED 2014/68 / EU. The conformity assessment procedure depends on the pressure and the nominal size of the respective valve. Following the replacement of the old Pressure Equipment Directive PED 97/23 / EC, however, all previous certificates remain valid. The previous EC Declaration of Conformity will be replaced by the new Pressure Equipment Directive of the EU Declaration of Conformity.

What sets your product line apart from your competitors?

As a medium-sized, owner-managed family business, we differ in many respects from traditional holding or listed companies. Whether owner, employee or customer, we place special emphasis on sustainability. This means that finding a targeted solution for our customers comes before profits. In addition, we guarantee dependability through committed employees, many years of experience, quality and environmental management as well as continuous and extensive certification both at home and abroad. We have representatives in many European countries, Asia, the Middle East, CIS countries, South Africa, South America and Australia. In short, for us, flexible solutions, high quality and long service life are not just slogans. We live it!

What happens in the event of compressed air failure?

Operating a pneumatically operated pinch valve is relatively simple. By supplying a pressure of at least 2 bar, a flexible elastomer sleeve is compressed into a lip-shape which closes the pipe cross-section. Generally speaking, the pressure is supplied via compressed air. If the air supply fails and the air escapes, the pinch valve opens automatically.

Is there a pneumatic pinch valve from PREMA-SERVICE with a safety position (closed by default)?

If the escape of the control air and the associated automatic opening of the pinch valve pose a risk for safety reasons, the pneumatically operated pinch valves can be equipped with a safety switch. This ensures that the valve remains closed in the event of power or compressed air failure. In the case of pipe pinch valves, spring-loaded pneumatic cylinders can also be used. This ensures the pinch valve can control the shut off and regulation or dosing of solid or liquid materials.

Does vibration in the system damage the pneumatically operated pinch valve?

A pneumatically operated pinch valve consists of both rigid and solid as well as elastic components. The assembly is relatively simple. The elastomer sleeve is clamped by the two flanges in the valve. PREMAFLEX pinch valves are not known to suffer damage due to vibration. In principle, however, precautionary measures should always be taken to ensure that all pipelines are laid stress-free to prevent possible damage.

How are the pneumatically operated pinch valves maintained and what are the spare/wear parts?

A pneumatically operated pinch valve from PREMA-SERVICE does not require any extraordinary maintenance. The components are largely wear-free. Only the elastomer sleeve should be checked at regular intervals and replaced if necessary. Replacing the sleeve of the pinch valve can be done in a few simple steps once the clamping flanges are released. There are detailed instructions included in the technical documentation of every PREMAFLEX pinch valve.

What is the optimal installation position for the pneumatic pinch valves?

The ideal installation position of a pinch valve is horizontal with the air connection placed underneath. In principle, however, a PREMAFLEX pinch valve can be installed in every imaginable position. Even an upwards facing air connection is not a problem as long as one pays attention to whether the compressed air is accumulating condensation, which must be discharged at regular intervals.

Are pneumatically operated pinch valves gas-tight?

Pneumatically operated pinch valves are not gas-tight. If there is sufficient differential pressure between the control air and the operating pressure, a pinch valve possesses a certain degree of water-tightness. That is, it is leakproof. However, a pinch valve is considered hermetically sealed to the outside.

What is the air consumption of the pneumatically operated pinch valves per closing operation?

The goal of every user is to keep their energy costs as low as possible. Of course, this includes the use of compressed air. Our aim is to minimize the consumption of the control air while improving the functionality. Our PREMAFLEX pinch valve is one of the most economical pinch valves on the market in terms of air consumption. The required air volume of a closed pinch valve depends on the nominal diameter and can be found in the respective technical data sheets.

How do I find the most suitable pneumatically operated pinch valve for my application?

Customer-oriented, technical advice is important to us, meaning we would never leave you to choose a pneumatically operated pinch valve without assistance. We can only guarantee a perfect fitting if we are able to see the actual pipe system, however. The more application details we are aware of, the more accurately we can meet your budget and technical requirements and provide you with proper specifications.

Is a pneumatically operated pinch valve suitable for flood or even underwater installations?

The total hermetic tightness against the outside air and the waterproofness allow for use even under water. Please provide your exact application case with the order; that way we can dimension the pinch valve correctly and, in the event of underwater usage, fit it with the appropriate coat. A pinch valve used under water requires a special coating to prevent rapid decay.

How does the pneumatic operated pinch valve open?

If there is no control air on the sleeve of the pinch valve, there are two properties that ensure it quickly and completely returns to its compressed lip shape. The first is that the sleeve has an enormous rebound resilience, meaning the elastomer remembers its starting position and quickly springs back to it. The second is that the existing service pressure within the pipeline itself forces the sleeve back to its starting position. The service pressure is not absolutely necessary as it only supports the opening process.

How high is the closing pressure of a pneumatically operated pinch valve?

Pneumatic pinch valves generally require a minimum closing pressure of 2 bar. The closing pressure corresponds to the delta between the medium pressure and the control air. This depends on the nominal diameter and may also be less than 2 bar. The exact closing pressures can be found in the technical data sheets.

Is it possible to reduce or optimize the closing and opening times of pneumatically operated pinch valves?

There are various ways to reduce or optimize the opening and closing times of the pinch valves. For one, compressed air supply lines with a larger cross-section can be installed. Another possibility is to install a magnetic valve with a higher throughput volume. Finally, quick exhaust valves can be used. The higher throughput volume reduces the respective times. The results are more efficient work and better outcomes.

Is there a pneumatically operated pinch valve that closes in the event of air failure?

Pinch valves are designed in such a way that they open automatically in the event of air failure. To prevent this, mechanical pinch valves with a spring-closing pneumatic cylinder are used, which guarantees the pinch valve will close in the event of air failure.

How do I get a position feedback that indicates whether the pneumatically operated pinch valve is open or closed?

This can be dealt with easily using a pressure switch. However, this is not as efficient as a mechanical pinch valve. This is due to mechanical pinch valves having so-called end position sensors, the job of which cannot be managed perfectly by pressure switches.

Is it possible to operate a pneumatically operated pinch valve with water or nitrogen?

It is possible to operate a pneumatically operated pinch valve with mediums other than compressed air. In this case, all common neutral gases or fluids can be used, meaning it is possible to use water or nitrogen as the medium: Compressed air is not the only option.

What housing and flange materials are available for the pneumatically operated pinch valves?

In the case of the pneumatically operated pinch valve, it is of course also possible to determine and select a material for the housing and the flange. This depends on where the pinch valve is to be used and what function it should perform. The metallic materials are grey cast iron, aluminium, steel and stainless steel. In addition, various plastics are available. The plastic pinch valve has a high resistance against many chemical influences as well as a high hardness and rigidity.

Can the opening and closing of a pneumatically operated PREMAFLEX pinch valve be prevented in the event of compressed air and/or power failure?

Yes, by means of a security switch. This will prevent the pinch valve from opening or closing in the event of air and/or power failure.

The safety switch consists of a check valve, pressure regulator, compressed air reservoir and a corresponding magnetic valve (electroless open or electroless closed). Please contact us if necessary.

Which accessories do you recommend for pneumatically operated pinch valves?

The pneumatically operated pinch valve has an extensive package of accessories. A pressure/filter regulator, a pressure switch and a quick exhaust valve are all recommended. A magnetic valve must be installed in order to control the pneumatically operated pinch valve.