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)

• Exhaust pressure= atm generally• Base pressure = pressure pump gets down to• Compression ratio = exhaust/base= big

number• Boyles Law P1V1=P2V2

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 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 400-600 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 maintenanceIf 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.

http://www.sisweb.com/vacuum/sis/iseries-maintkit.htm

Pump specsDisplacement

50Hz 3.7 m3h-1 / 2.2 ft3min-1

60Hz 4.5 m3h-1 / 2.6 ft3min-1

Speed (Pneurop 6602)

50Hz 3.3 m3h-1 / 2 ft3min-1

60Hz 3.9 m3h-1 / 2.3 ft3min-1

Ultimate pressure (high vac mode) 2.0 x 10-3 mbar / 1.5 x 10-3 TorrUltimate pressure GB I (high vac mode) 3.0 x 10-2 mbar / 2.3 x 10-2 TorrUltimate pressure GB II (High throughput mode) 1.2 x 10-1 mbar / 9.1 x 10-2 Torr

Max inlet pressure for water vapour 80 mbar / 60 TorrMax water vapour pumping rate – GB I 60 g/hMax water vapour pumping rate – GB II 220 g/hMax allowed outlet pressure 1 bar gauge / 14 psigMax allowed inlet and gas ballast pressure 0.5 bar gauge / 7 psigMotor power 50/60Hz 450 / 550WNominal rotation speed 50/60Hz 1500 / 1800rpmWeight (without oil) 25 kg / 55 lbOil capacity min/max 0.42/0.7 litresRecommended oil Ultragrade 19Inlet flange NW25Exhaust flange NW25Noise level 48 dBA @ 50 HzOperating temperature range 12 – 40 °C

Spec sheet for anEdwards A65209903RV rotary vane pump

$3171

Pumping Speed N2 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) H2 ISO63/63CF (DN40NW)(ISO100) 53 ls-1 (48 ls-1) (54 ls-1)

Compression ratio N2 >1 × 1011

He 1 x 106

H2 5 x 104

Ultimate Pressure (mbar) With RV backing pump ISO/CF <5 x 10-9 / 5 x 10-10

With diaphragm backing pump ISO/CF <5 x 10-8 / 5 x 10-9

Outlet flange DN16NWRecommended backing pump* RV5/XDS5Vent port 1/8 inch BSPPurge port 1/8 inch BSP

Max continuous inlet pressure (light gas pumping)†

Water cooling (water at 15 °C, ambient temp at 40 °C)

2 × 10-2 mbar

Forced air cooled, 35 °C ambient 1 × 10-2 mbarPump rotational speed Nominal rotational speed 90000 rpm

Standby rotational speed Variable from 49500 to 90000 rpm (63000 rpm default)

Programmable power limit settings Variable from 50-120W (80W default)Start time to 90% speed 110 s ‡Analogue outputs Rotational speed;

Power consumption; Pump temp; Controller tempCooling method? Forced air / waterAmbient air temperature for forced air cooling

5 - 35 °C

Min cooling water flow rate (water 15 °C)

15 l h-1

Water temp range 10 - 20 °CMax inlet flange temp 100 °C

Subset of specs for Edwards EXT 556H turbomolecular pump

Pum

p Sp

eed

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.

www.vacuumresearchcorp.com/pdfs/valves/nwflanges06.pdf

Pumps on the Delta S

• Pumping system for Analyzer– Turbo molecular pump TPH 050– Vacuum pump E2 M1, 52

• Differential Pumping system– Turbo molecular pump TPH 050– Turbo molecular pump TPH 240– Vorvakuumpumpe E2 M5, 50160 Hz

Turbo molecular pump TPH 050 Turbo molecular pump TPH 240

Units of pressure for your notes

Pascal(Pa)

Bar(bar)

Technical atmosphere(at) Atmosphere

(atm)Torr

(Torr)

Pound-force persquare inch

(psi)

1 Pa ≡ 1 N/m2 10−5 1.0197×10−5 9.8692×10−6 7.5006×10−3 145.04×10−6

1 bar 105 ≡ 106 dyn/cm2 1.0197 0.98692 750.06 14.5037744

1 at 0.980665 ×105 0.980665 ≡ 1 kgf/cm2 0.96784 735.56 14.223

1 atm 1.01325 ×105 1.01325 1.0332 ≡ 1 atm 760 14.696

1 Torr 133.322 1.3332×10−3 1.3595×10−3 1.3158×10−3 ≡ 1 Torr; ≈ 1 mmHg 19.337×10−3

1 psi 6.895×103 68.948×10−3 70.307×10−3 68.046×10−3 51.715 ≡ 1 lbf/in2