Absolute Vacuum Services Limited are Vacuum Pump Specialists For The Following Vacuum Pump Manufacturers:
Alcatel Vacuum  Becker vacuum  Busch Vacuum  Edwards Vacuum  Formerly BOC Edwards Vacuum  Leybold Vacuum  Pfeiffer vacuum  Stokes pumps  Varian vacuum

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Absolute Vacuum Services Ltd present the Edwards Vacuum ® range of vacuum pump products
    Absolute Vacuum is a non-affiliated reseller of Edwards Vacuum ® products  

Turbo vacuum pumps: Edwards (formely known as BOC Edwards) turbomolecular vacuum pumps

Edwards vacuum (formerly BOC Edwards) Turbomolecular pumps: Edwards EXT556H compound turbomolecular pump

Edwards (formerly BOC Edwards) Vacuum - Turbo pumps and accessories


EXT turbomolecular pumps

EXT75DX compound turbomolecular pump
EXT255DX compound turbomolecular pump
EXT255H compound turbomolecular pump
EXT406PX compound turbomolecular pump
EXT556H compound turbomolecular pump


Turbomolecular pump controllers

Edwards Vacuum: EXC controllers
Edwards Vacuum: TIC turbo controller
Edwards: TIC turbo & instrument controller


EXT accessories

Edwards EXT accessories
EXT pump to controller cable
EXT ACX air-cooler
EXT BX bakeout band
EXT PRX10 purge-restrictor
EXT TAV vent-valve
EXT Vent-port adaptor
EXT Vibration isolator
EXT VRX vent-restrictor
EXT turbo pump spares


EXPT combined outfits

Edwards EXPT 1 &2 pumping stations


STP magnetically levitated turbomolecular pumps and accessories

Edwards Vacuum - STP turbo pumps
STP-XA4503C turbomolecular pump
STP-iX455 turbomolecular pump
STP301/STP301C turbomolecular pump
STP-L301/STP-L301C turbomolecular pump
STP603/STP603C turbomolecular pump
STP1003/STP1003C turbomolecular pump
STPH301C high performance turbo pump
STPH451C high performance turbo pump
STPA803C "advantage" turbo pump
STPA1303C "advantage" turbo pump
STPA1603C turbomolecular pump
STPA2203C "advantage" turbo pump
STP-XA2703C turbo pump
STP-XA3203C turbo pump


Edwards turbo molecular pumps (turbo vacuum pumps) overview, information and definitions

A turbomolecular pump (TMP)
A compound molecular pump (CMP)
Turbo vacuum pumps - pumping speed
Turbo vacuum pumps - quiescent electrical power
Turbo vacuum pumps - compression ratio
Turbo vacuum pumps - ultimate pressure
Turbo vacuum pumps - bearing and suspension
Turbo vacuum pumps - rotor
Turbo vacuum pumps - motor
Turbo vacuum pumps - corrosive applications
Turbo vacuum pumps - purge port
Turbo vacuum pumps - venting
Turbo vacuum pumps - inlet screen
Turbo vacuum pumps - cooling
Turbo vacuum pumps - scope of supply
Our range of EXT turbomolecular and compound molecular pumps and EXC Controllers uses state-of-the-art technology to provide reliable, high and ultra high vacuum. The EXT556H incorporates our hybrid bearing and enhanced molecular drag pumping technologies with turbomolecular pump stages on a single rotor. The result is a highly reliable pump well suited to applications requiring excellent light gas performance and ultimate pressures <10-10 mbar. With the optional ferromagnetic envelope the EXT556H excels in applications, such as FTMS, where high magnetic fields are present.

Edwards EXT556H compound turbomolecular pump


Edwards EXT556H compound turbomolecular pump
EXT556H with DN160ISO-K and DN160CF inlet flange


Edwards EXT556H compound turbomolecular pump - Features & benefits

  • High critical backing pressure
  • High volume flow rate
    • Fast pump down
  • Multistage Holweck molecular drag mechanism gives high compression ration for light gases
  • Ultimate vacuum <10-10 mbar
  • Proven EXT performance and reliability
  • Hybrid bearing configuration
  • Maintenance free . oil bearing reservoir sealed for life
  • Machined monobloc rotor
  • DC motor drive


Edwards EXT556H compound turbomolecular pump -
Technical data

Main inlet flange: DN160ISO-K / DN160CF
Outlet flange: DN25NW
Vent port: 1/8 inch BSP
Purge port: 1/8 inch BSP
Inlet pumping speed*

N2 540 l s-1
He 580 l s-1
H2 500 l s-1
Ar 510 l s-1

Compression ratio

N2 >1010
He 108
H2 106
Ar >1010

Ultimate pressure (CF variant): <10-10 mbar
Recommended backing pump: RV12
Maximum continuous inlet pressure (N2, He, H2)**

forced air cooled, 30 °C ambient: 1x10-3 mbar
forced air cooled, 35 °C ambient: 5x10-4 mbar

water cooling at 15 °C: 2x10-3 mbar
Nominal rotational speed: 50000 rpm
Start time to 90% speed

EXC250: 5 min
EXC300: 6.5 min
EXDC160: 8 min

Cooling method: forced air / water
Ambient air temperature for forced air cooling: 0 °C – 35 °C
Recommended cooling water flow rate (water at 15 °C): 15 L h-1
Water temperature: 10 - 20 °C
Maximum inlet flange temperature: 80 °C
Operating attitude: Vertical and upright, through to horizontal
Noise level at 1 metre: <60 dBA
Maximum magnetic field (standard envelopes)

Axial: < 7 mT
Radial: < 3 mT

Maximum magnetic field (martensitic envelopes)

Axial: < 50 mT
Radial: < 50 mT

Recommended controllers: EXC250, EXC300
Quiescent power consumption: 35 W

* Measured without inlet screen. Inlet screens are supplied fitted and may reduce speed by up to 20%

** With backing pressure < 0.3 mbar. Above this inlet pressure rotational speed drops.



Edwards EXT556H compound turbomolecular pump – Pumping speed

EXT556H turbo pump -  pumping speed vs inlet pressure

Edwards EXT556H compound turbomolecular pump – Pumping speed



Edwards EXT556H compound turbomolecular pump – Throughput

EXT556H turbo pump - throughput vs inlet pressure

Edwards EXT556H compound turbomolecular pump – Throughput



Edwards EXT556H compound turbomolecular pump – Dimensions

Edwards EXT556H compound turbomolecular pump – Dimensions

A Inlet ISO100

B Inlet ISO160

C Vent port

D Earth stud

E Purge port

F Backing port

G Electrical connector

H Base mount holes (8)/Rubber feet (4)



Edwards EXT556H compound turbomolecular pump – Ordering information

Product description                                                                                                             Order No.

                                                                                        Pump Inlet flange

EXT556H ISO160                                                        DN160ISO-K                                     B77751000

EXT556H CF160                                                         DN160CF-K                                      B77752000

EXT556H ISO160 (fine inlet screen)                         DN160ISO-K                                      B77761000

Martensitic envelope

EXT556H ISO160*                                                      DN160ISO-K                                      B77757000

EXT556H CF160*                                                       DN160ISO-K                                      B77758000

* HF pumps have Martensic envelopes for use in high magnetic field environments of up to 50 mT.

Accessories Order No.

For safe and reliable operation, the EXT555H requires one of the following external cooling accessories

ACX555 Air cooling accessory                                                                                             B58053561

WCX555 Water cooling accessory                                                                                       B58067003