Vacuum Pumps

Basics vac·u·um – noun 1. a space entirely devoid of matter. – 2. an enclosed space from which matter, especially air, has been partially removed so that the matter or gas remaining in the space exerts less pressure than the atmosphere ( opposed to plenum). (dictionary.com)whichplenum Exhaust pressure= atm generally Base pressure = pressure pump gets down to Compression ratio = exhaust/base= big number Boyles Law P 1 V 1 =P 2 V 2

History of vacuum pumps Suction pumps go way back (Romans, Byzantine empire, etc) Major improvements on the idea of vacuum made by Galileo, Evangeilist Torricelli, and Blaise Pascal Otto von Guericke made first pump and famous for Magdeburg hemispheres experiment

Types of Vacuum pumps Positive displacement pumps – Expand a cavity, seal, exhaust, repeat Momentum transfer pumps (molecular pumps) – High speed liquids or blades to knock gasses around Entrapment – Create solids or adsorbed gases (cryopumps)

Roughing pumps Pumps from atm pressure down to rough vacuum (0.1 Pa, 1X10 -3 torr) Necessary because turbo pumps have trouble starting from atmospheric pressure Usually Rotary Vane pumps Can have oil or not

Rotary vane pumps Oil Sealed Rotary Pumps Understanding Gas BallastOil Sealed Rotary Pumps Understanding Gas Ballast www2.avs.org/chapters/nccavs/pdf/Gas_Ballast_OilSealedPumps.pdf

Rotary vane pumps Works by increasing the gas/vapor ratio (air is mostly gas) As you might imagine this interferes with the final vacuum Condensation of vapor in the gas mixture is a problem with these pumps. Solution Ballasting

Types One stage or two stage Belt Drive or direct drive Slower RPM Bigger, Cheaper Faster 1500 to 1725 RPM Smaller, lighter

Turbo (molecular) pumps Gas molecules interact with spinning blades and are preferentially forced downward High vacuum (10 -6 Pa) requires rotation of 20,000 to 90,000 revolutions per minute Generally work between 10-3 and 10-7 Torr Ineffective before gas is in “molecular flow”

Options: – Bearings: Ceramic (oil lubricated) Magnetic (supported w/out physical contact), also hybrid – Rotor options (Blade configuration) – Cooling (air or water) Turbo (molecular) pumps

Pump Care Rough pumps shouldn’t need a lot of maintenance If they do repair kits are available: Minor kit includes all necessary seals (shaft seals, valves, o-rings, etc) Major kit includes Minor Kit components plus vanes, springs, plugs, etc. Seem to be available for most major brands and types Turbopumps should need even less maintenance, bearings can wear out but must be replaced by manufacturer for balancing.

Pump specs Displacement 50Hz3.7 m 3 h -1 / 2.2 ft 3 min -1 60Hz4.5 m 3 h -1 / 2.6 ft 3 min -1 Speed (Pneurop 6602) 50Hz3.3 m 3 h -1 / 2 ft 3 min -1 60Hz3.9 m 3 h -1 / 2.3 ft 3 min -1 Ultimate pressure (high vac mode)2.0 x mbar / 1.5 x Torr Ultimate pressure GB I (high vac mode)3.0 x mbar / 2.3 x Torr Ultimate pressure GB II (High throughput mode)1.2 x mbar / 9.1 x Torr Max inlet pressure for water vapour80 mbar / 60 Torr Max water vapour pumping rate – GB I60 g/h Max water vapour pumping rate – GB II220 g/h Max allowed outlet pressure1 bar gauge / 14 psig Max allowed inlet and gas ballast pressure0.5 bar gauge / 7 psig Motor power 50/60Hz450 / 550W Nominal rotation speed 50/60Hz1500 / 1800rpm Weight (without oil)25 kg / 55 lb Oil capacity min/max0.42/0.7 litres Recommended oilUltragrade 19 Inlet flangeNW25 Exhaust flangeNW25 Noise level48 50 Hz Operating temperature range12 – 40 °C Spec sheet for an Edwards A RV rotary vane pump $3171

Pumping Speed N 2 ISO63/63CF (DN40NW)(ISO100)61 ls -1 (42 ls -1 ) (66 ls -1 ) He ISO63/63CF (DN40NW)(ISO100)57 ls -1 (49 ls -1 ) (59 ls -1 ) H 2 ISO63/63CF (DN40NW)(ISO100)53 ls -1 (48 ls -1 ) (54 ls -1 ) Compression ratio N 2 >1 × He1 x 10 6 H 2 5 x 10 4 Ultimate Pressure (mbar)With RV backing pump ISO/CF<5 x / 5 x With diaphragm backing pump ISO/CF<5 x / 5 x Outlet flangeDN16NW Recommended backing pump*RV5/XDS5 Vent port1/8 inch BSP Purge port1/8 inch BSP Max continuous inlet pressure (light gas pumping) † Water cooling (water at 15 °C, ambient temp at 40 °C) 2 × mbar Forced air cooled, 35 °C ambient1 × mbar Pump rotational speedNominal rotational speed90000 rpm Standby rotational speedVariable from to rpm (63000 rpm default) Programmable power limit settingsVariable from W (80W default) Start time to 90% speed110 s ‡ Analogue outputsRotational speed; Power consumption; Pump temp; Controller temp Cooling method ? Forced air / water Ambient air temperature for forced air cooling °C Min cooling water flow rate (water 15 °C) 15 l h -1 Water temp range °C Max inlet flange temp100 °C Subset of specs for Edwards EXT 556H turbomolecular pump

Pump Speed Pressure Rotary Vane: Pump speed lower at low vacuum Turbo pumps: opposite

Useful fitting terminology Flanges – Standard quick Release (QF, KF, NW, or DN) Named based on internal diameter DN16KF is 16mm (16-50mm) – Large Quick releases (LF, LFB, MF or ISO) Clamps or bolts (63-500mm) – Conflat (CF) used in ultra high vacuum settings, usually metal to metal seals Sizing odd: Europe inner diamter in mm, NA outer diameter in inches

Sizes we will likely find.

Pumps on the Delta S Pumping system for Analyzer – Turbo molecular pump TPH 050 – Vacuum pump E2 M1, 5 2 Differential Pumping system – Turbo molecular pump TPH 050 – Turbo molecular pump TPH 240 – Vorvakuumpumpe E2 M5, Hz

Turbo molecular pump TPH 050Turbo molecular pump TPH 240

Units of pressure for your notes Pascal Pascal (Pa) Bar Bar (bar) Technical atmosphere Technical atmosphere (at) Atmosphere Atmosphere (atm) Torr Torr (Torr) Pound-force per square inch Pound-force per square inch (psi) 1 Pa≡ 1 N/m 2N 10 − ×10 − ×10 − ×10 − ×10 −6 1 bar10 5 ≡ 10 6 dyn/cm 2dyn at × ≡ 1 kgf/cm 2kgf atm × ≡ 1 atmatm Torr ×10 − ×10 − ×10 −3 ≡ 1 Torr; ≈ 1 mmHgmmHg ×10 −3 1 psi6.895× ×10 − ×10 − ×10 − ≡ 1 lbf/in 2lbf