Extrusion International 2-2020

39 Extrusion International 2/2020 Busch Vacuum Solutions Schauinslandstr. 1, 79689 Maulburg, Germany www.buschvacuum.com aquatherm GmbH Biggen 5, 57439 Attendorn, Germany www.aquatherm.de operating fluids and thus provide completely dry com- pression of intake air. The moving parts within MINK vac- uum pumps do not come into contact with each other. So there is no resulting friction that would make lubrication of the parts necessary. No friction also means no wear. For Markus Korth, who is responsible for maintenance, this means he does not need to replace spare parts or worry about work associated with operating fluids like oil. Because aquatherm runs a three-shift operation seven days a week, the vacuum supply needs to operate reliably almost around the clock. This is why an internal maintenance team annually changes gear oil in the vac- uum pumps as a preventive measure. Today, aquatherm uses a total of 29 MINK claw vacuum pumps for material feed, supplying a total of 22 material feed circuits with vacuum. All vacuum pumps (Picture 2) are located in a machine room and are easily accessible. Over the past 20 years, the number of MINK claw vacuum pumps has grown parallel to aquatherm’s success and the associated production increase. This vacuum technology provides a further benefit: Claw vacuum technology has the highest efficiency factor of all mechanical vacuum pumps. By eliminating internal fric- tion and thus the need for operating fluids, MINK claw vacuum pumps are extremely energy efficient. The only change at aquatherm since the first MINK vacuum pumps were delivered 20 years ago, is that the IE1 motors have been exchanged for today’s standard motors in energy efficiency class IE3. PP-R is delivered to aquatherm as a raw material in pel- let form and then processed to create a master batch using additives, stabilizers and pigments in compound- ing extruders. The polyolefin-based thermoplastic PP-R is excellently suited for use in potable water and heating installations due to its high heat and extraction stability. When used in potable water installations, its absolute corrosion resistance is of great significance for hygienic reasons. The pipeline systems are also used for industrial applications in pressure and vacuum lines. At ten of the 19 extruders (Picture 3) the molten PP R is degassed us- ing the MINK claw vacuum pump. A standing filter from Busch directly attached to the extruder prevents water vapor, residual monomers, and other by-products and degradation products resulting from chemical reactions, temperature load, and shear stress in the molten material from entering the vacuum pump, potentially leading to splitting. For nearly 17 years aquatherm has also been using MINK claw vacuum pumps for degassing molten material. The ten extruders that need to be degassed are each con- nected in parallel to two MINK claw vacuum pumps in constant operation. Both of these vacuum pumps are also set up in a separate machine room. For safety purposes, an inlet filter is installed directly on the vacuum pump’s gas inlet. However, if any cracking occurs inside the vac- uum pump, which can happen on occasion, two vacuum pumps are available as a reserve and can be immediately switched in. Contaminated or cracked vacuum pumps can be easily dismantled, cleaned and reassembled by the maintenance team. They are immediately operational af- ter that. Maintenance Manager Markus Korth says: “Our maintenance staff is able to dismantle MINK claw vacu- um pumps in 20 minutes.” Maintenance effort and thus maintenance costs are significantly lower than the previ- ously used liquid ring vacuum pumps. These use water as an operating fluid, which needed to be checked on a daily basis and replenished, if necessary. Furthermore, the entire water circulation system required regular cleaning. Correct disposal of the operating water also took addi- tional time and produced further costs. After about 20 years of using MINK claw vacuum technology, the team at aquatherm is very satisfied. The high degree of opera- tional safety and reliability as well as the high economic efficiency – thanks to energy-efficient operation and low maintenance costs – speak for themselves. Picture 3: Extrusion facility: aquathermmanufacturers PP-R pipes with diameters of 16 to 630 millimeters (Picture: aquatherm)