Explosion proof mechanical booster pumps are certified for use within potentially explosive atmospheres.

The EH500C mechanical booster pump has been certified for use in CSA Division 1 area Gas Class I Group C D and Dust Class II Group F G, Temperature Class T3C. The temperature classification of the pump is based on the outlet pressure of the pump being maintained below the critical backing pressure of 10 mbar (1 x 103 Pa) at zero flow.

The EH mechanical booster pump, based on the simple Roots principle, remains the favourite pump for applications where high pumping speeds are required for pressures in the region of 0.01 to 10 mbar. This pump must always be backed by another pump, which can deliver against a high-pressure differential to atmospheric pressure.

Operating at relatively low pressures, the mechanical booster pump is not exposed to the same concentrations of corrosive process media as is the backing pump, which makes it highly reliable.

Explosion proof mechanical booster pumps may be supplied with explosion proof motors individually or part of an explosion proof system. Please consult Edwards.

Features and Benefits

  • Suitable for applications where high pumping speeds over 3000 m3h-1/1776 ft3min-1 are required in the pressure region of 0.01 to 50 mbar/0.0075 to 37.5 Torr.
  • Operating at relatively low pressures makes it highly reliable.
  • The EH pumps have a high quality, oil-free pumping mechanism. This offers:
    • Quiet, vibration free operation.
    • ­Rugged and corrosion resistant.
    • ­Advanced shaft-seal technology with no oil contamination of the process chamber
  • The corrosion resistant pumping mechanism is manufactured from high grade cast iron.
  • The proven shaft-seal arrangement ensures that no oil enters the pumping stator, and the absence of internal and external by-pass lines and valves which may corrode or stick minimizes maintenance requirements.
  • The design of the shaft seals is optimized to ensure that no lubricants can migrate into the pumping mechanism. This maintains booster pump performance in applications which demand the highest standard of cleanliness. In addition, this prevents the build-up of trapped particles on the rotor lobes and end-faces which have very close tolerances.
  • The dynamically balanced rotors and precision ground gears contribute to the smooth, quiet operation of the pumps, as demanded by manufacturers of advanced technology equipment.


  • Semiconductor processing
  • Vacuum distillation
  • Vacuum packaging
  • Steel de-gassing
  • Thin film coating
  • Vacuum metallurgy
  • Low density wind tunnels
  • Space simulation
  • Vacuum impregnation
  • Oil drying and de-gassing
  • Pharmaceutical freeze drying
  • CO2 lasers
Technical data  
Displacement (swept volume)  
  50Hz 505 m3h-1 / 300 ft3min-1
  60Hz 605 m3h-1 / 335 ft3min-1
Effective pumping speed with backing pump  
 E2M40 350 m3h-1 / 206 ft3min-1
 E2M80 400 m3h-1 / 236 ft3min-1
 E2M175 440 m3h-1 / 259 ft3min-1
 E2M275 460 m3h-1 / 271 ft3min-1
Pressure differential across pump  
  50Hz 0-110 mbar / 0-83 Torr
  60Hz 0-90 mbar / 0-68 Torr
Inlet connection ISO100
Outlet connection ISO63
Rotational speed  
  50Hz 0-2900 rpm
  60Hz 0-3500 rpm
Operating continuous inlet pressure 0-1000 mbar / 0-760 Torr
Maximum outlet pressure 1000 mbar / 760 Torr
Recommended backing pumps GV80, E2M80, ES100, ES200, ES300
Electrical supply  
  50Hz 220-240V / 380-415V
  60Hz 208-230V / 460V
Motor power  
  Hydrocarbon 2.2 kW / 3hp
  PFPE 2.2 kW / 3hp
  ATEX 2.2 kW
  Explosion proof 3hp
Ambient temperature range  
  Operating 5 to 40°C / 40 to 104°F
  Storage -10 to 80°C / 14 to 176°F
Maximum operating humidity 90% RH
Recommended oil  
  Standard version Ultragrade 20
  PFPE version Fomblin® YVAC 16/6
Oil capacity  
  Coupling cover 1.5 litre
  Shaft seal reservoir 0.125 litre
Weight 100 kg