Measures for greater safety when handling silane

modifications to the flow rates, connection voltage, system hierarchy and product supply without a hitch. Stainless steel was used for the pump housing and PTFE was used for the sandwich diaphragm. These materials show hardly any wear, even when pumping aggressive fluids.

How precisely silane can be metered during continuous plastics processing has a direct influence on the quality of the end product. This is why fast and precise control of the flow rate must always be guaranteed – even when different types of silane are being used for different products. Lewa GmbH from Leonberg, Germany, has a customer that faced this very challenge


ilane crosslinking is an established process that improves the

performance of cables. In comparison to thermoplastic polymers, crosslinked polymers achieve much better results when it comes to resisting heat, deformation and weather effects as well as electric flow and creep behaviour. In addition, the process has the advantage of requiring much less energy for the procedure compared to similar methods such as radiation crosslinking. The results are lower operating costs for production and environmental conservation. One company that uses this process is a customer of Lewa GmbH. Depending on the application and product, the customer (a cable manufacturer) uses various types of silane to produce cable insulation, such as aminosilane or vinylsilane. Since silanes are usually highly flammable as well as highly reactive in combination with atmospheric oxygen, the systems used for metering must make safe handling possible. For these purposes, the company has been relying on customised metering systems from the pump experts. The Lewa Ecoflow diaphragm metering


pumps are the core of the new systems. Customers have the option to select from a variety of pump head types (diaphragm or packed plunger pump head), materials and surfaces, which means that their systems can be built to handle a wide range of fluids, including flammable, toxic, abrasive, viscous, environmentally harmful and sensitive fluids. The Ecoflow series can be used for flow rates up to 19m³/h per pump head (the model used by the customer operates between 0.5 and 10 l/h) and discharge pressures up to a maximum of 1,200 bar. Tank sizes also vary between 60 and 240l/h. The hydraulically actuated pump heads stand out in particular for their high operating reliability as well as a long service life, which is made possible by features such as the patented diaphragm protection system (DPS). This ensures that the pumps remain hydraulically stable even in the event of accidents or operating errors. As a result, the pumps are extremely reliable and have low maintenance and operating costs. The systems have also been adapted to the customer's specific requirements. This way, it is possible to make

Figure 1:

The Lewa Ecoflow diaphragm metering pumps are the core of the new systems

MEASURES FOR GREATER SAFETY WHEN HANDLING SILANE Lewa took a variety of steps to guarantee the level of safety required by the customer for the handling the silane being used. These steps included designing the system in accordance with Ex-Zone 2 and equipping it with continuous monitoring for certain parameters such as fill level, flow rate and pressure or diaphragm status. Additionally, an inert atmosphere is created by nitrogen blanketing. The "Smart Control" controller allows

for intuitive operation using a colour touch panel directly on the control cabinet. The controller is integrated into the higher-level system control. Among other features, the touch panel delivers a general graphic overview of the individual processes and parameters as well as a summation of production related data. This data can then be used as a foundation for initial analyses in the event that maintenance should be required. Using an optional data connection, Lewa is able to connect to the system directly and provide support from their headquarters in Leonberg. This data connection even allowed it to provide the customer with support during commissioning. Thereby, the process was able to be significantly shortened.

To ensure optimal reproducibility,

consistency and product purity of the plastics, it is necessary for the silane to be metered precisely and independently of external influences. The fact that the customer once again called upon the company to implement this process at various plants shows that Lewa has truly earned the trust of this customer thanks to its technical expertise.

Lewa T: +49 7152 140 e:


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