Special rotary lobe pumps meet even the strictest legal requirements

Tornado T2 NetzschEuropean commercial and industrial companies must comply with strict regulations regarding manufacturing, pump systems, and more, in order to ensure the protection of users and the environment. One of the pump market leaders in this area, Netzsch Pumpen & Systeme, designs and manufactures all its systems to ensure that they meet all applicable regulations, and can meet individual requirements at client request. At the start of 2014 a major chemical producer was supplied with a T.Proc rotary lobe pump specially designed to convey corrosive fatty acid, and is both ATEX-compliant and complies with TA Luft air quality specifications.

The cosmetics industry and the paint and varnish industry are the primary users of fatty acids in production processes. Depending on the chemical composition, concentration and volatility, the acids can burn the skin or even the respiratory tract. The medium therefore comes under the area of the Technical Instructions on Air Quality (TA Luft), which regulates emissions and immissions of hazardous substances and environmental pollutants. At the same time, the installation area is Ex zone 1 due to possible gas accumulations, which means the pump has to be ATEX-compliant. The gear pump that the manufacturer had been using up to this point to feed its tankers was no longer able to meet this requirement and therefore had to be replaced.

Pump design for aggressive fatty acids

In order to fulfil both TA Luft and ATEX regulations, the operating company installed a T.Proc rotary lobe pump, specifically developed for difficult media. The customer chose an all-metal, high-strength steel design due to the aggressive substance and high conveying temperatures of 70ºC required to keep the fatty acids free-flowing.

The pump, part of the Netzsch Tornado T2 series features a design that creates a large free ball passage, ensuring problem-free conveyance. Additionally, backflow is kept low thanks to the long sealing line. The Netzsch Pulsation Reduction System (PRS), a special adaptation to the geometry of the pump chamber, ensures very low pulsation levels.

The whole pump structure is designed for robustness, operational reliability and the lowest possible maintenance costs. In this particular case, in order to ensure the hermetic separation of the fatty acid being conveyed from the surrounding atmosphere required by the TA Luft air quality specifications, Netzsch experts fitted the pump with a double-acting mechanical seal with a pressurised flushing system. The seal is permanently lubricated from the attached quenching pot, which prevents clogging and offers greater reliability than a single-acting seal. The mechanical seals of the T2 series have a cartridge design and are easily fitted onto the shaft along with the rotary lobes during assembly.

Compliance with the regulations for explosion protection zone 1 was also critical. It was possible to use the T.Proc without any risk because it is ATEX certified for medium temperatures of up to 100°C. In this application, the operating company installed an electrical heating band to prevent hardening of the medium in the pump housing which required a separate EX protection certification.

The pump has functioned reliably since installation, filling the manufacturer’s tankers at a volume of 20 m³/h and a pressure of 2.5 bar. In doing so, all legal requirements have been strictly adhered to, including TA Luft and ATEX regulations.

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