90061b5h25 - 61B 5H25, 25hp, 230/460V, 3-ph, 60Hz @ 3600rpm

61B 5H25, 25hp, 230/460V, 3-ph, 60Hz @ 3600rpm



Stokes 61B series process isolation boosters are designed to be used in conjunction with rotary-piston, dry vacuum, rotary vane and liquid ring pumps to increase pumping speed at working pressures and shorten pump down time significantly. It incorporates five mechanical seals for optimum protection from dust and particulate contamination. It also includes an integral by-pass valve enabling the booster to start from atmosphere, eliminating the need for a vacuum pressure switch to ensure continuous operation regardless of vacuum level. The Stokes 61B series can be mounted separately or on the inlet of the backing pump to create a compact integrated package. 

Featuring an extra large diameter shaft, the Stokes 6” series has the capability for use with higher powered motors in addition to ensuring a uniquely rugged and durable mechanical booster. This allows the pumps to operate at their full displacement from atmospheric pressure with an appropriately sized backing pump. 
The Stokes 6" series must be backed by a primary vacuum pump designed to discharge to atmospheric pressure. Examples of suitable backing pumps are listed below:
•  Microvac series piston pumps 
•  GV Drystar or Chemical Drystar dry pumps
•  EM or ES oil sealed pumps 
•  Two stage LR series liquid ring pumps


  • Automotive
  • Chemical processing
  • Heat treatment
  • Leak detection
  • Metallurgy
  • PET processing
  • Pharmaceuticals
  • Thermal processing
  • Transformer drying and cable fluid conditioning
  • Vacuum coating
  • Vacuum melting
  • Many other industrial applications

Features and Benefits

  • Mechanical shaft seal – improved life and serviceability
  • Ringfeder® keyless gear locking system – stronger, faster timing
  • Large shaft diameters – allowing improved performance at high pressures
  • Belt drive or direct drive capability
  • Vertical or horizontal gas flow  
  • Drive end roller bearing – resists belt pull and thermal effects
  • Over-sized anti-friction bearings – increased uptime and longer service intervals
  • Rugged proven design and construction
  • Quiet operation
  • Unique impeller design -Dynamically balanced to minimize vibration
  • High volumetric efficiency
  • High differential pressure – operation capability
  • Available by-pass option for improved pumpdown
  • Available process isolation seal option – optimum protection from dust and particulate contamination

Technical Data

  V belt (2750 rpm) 3375m3h-1 / 2000ft3min-1
  Direct drive (3000 rpm) 3685m3h-1 / 2170ft3min-1
  Direct drive (3600 rpm) 4420m3h-1 / 2600ft3min-1
Inlet/outlet flanges 8” ASA/ANSI flange
Motor power EU/Asia 18.5kW
Motor power US TEFC 25 hp
By-pass available Yes
Cooling water 7.6 - 11.4l min-1 / 2 - 3gal min-1
Oil capacity (horizontal flow) 1.9 litre / 4.1gal
Oil capacity (vertical flow) 4.1 litre / 8.8gal
Max temp rise 135°C / 275°F
Max discharge temp 191°C / 375°F
Weight bare shaft 284kg / 625lbs
Weight TEFC direct drive 538kg / 1185lbs
Recommended Oil  V- Lube H


A  8" pipe flange connection 13 1/2" (343 mm) OD x  8” (203 mm) ID 8 x 3/4-10 NC-2B x 1 1/8" (29 mm) holes straddle both CL both flanges
B  DIA. Holes
1.  STD Inlet 2. Optional feet
424-051-001 - 3.8 litres (1 US gal)

3.8 litres (1 US gal)

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419-699-001 - 19 litres (5 US gal)

19 litres (5 US gal)

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kit001378 - KIT STOKES 6 INCH – 1YR  SERVICE


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