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Dry running vacuum pumps
Dry vacuum pumps have been developed for the semiconductor industry in the 80's and introduced in chemical and pharmaceutical process industries in the early 90's. They are specified for fine chemicals and pharmaceutical (cGMP) plants in order to avoid a product contamination. They are multistage roots systems or screw- or claw-compressors.
Applications and Features suction capacities up to approx. 1000 m³/h Endvacuum < 1 mbarA - pressure control through speed control - compact - good efficiency - no contamination through oil or seal liquid Advantages and Disadvantages No auxiliary liquid = no lubrication-, no sealing- and no cooling-liquid => no lubrication => no contact between the parts => clearances (*) => no sealing => tight clearances and/or high speed => no cooling => high temperatures (**) * tight clearances + high temperatures => body in cast iron only ** high gas temperature => "hot spots", T3 Standard, T4 possible but relatively complicated. no seal liquid (= no contamination) => no product contamination => vapours are condensed and recovered at pump outlet. => no contamination of auxiliary liquid (oil, motive steam, seal liquid, etc..) => no cost for treatment and waste
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Dry vacuum pumps - FAQ's
dry vacuum pumps manufacturers more than 1000 m³/h suction capacity ? => Improved vacuum levels and shorter pumpdown times can be achieved by combining the dry vacuum pump with roots type mechanical booster(s) Sealing between Pump and Gear ? => with piston rings or mechanical seals, with/without purge gas how to avoid corrosion ? => operating temperature to be higher than product condensation temperature. => pre-heating with closed inlet valve, drying with N2 before shut-down. => outlet piping top to down or with a siphon to avoid bach-flow of condensate ATEX ? => SIHIdry: yes, without flame arrestors for Gases of Atex-categorie 2 (Zone 1) => BUSCH Cobra: yes, with flame arrestors for Zone 0 and Zone 1. speed control ? => instead of pressure control valve |
