Overview:
Stokes 61B by-pass mechanical 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. The Stokes 61B by-pass boosters include an integral by-pass valve enabling the booster to start from atmosphere, eliminating the need for a vacuum pressure switch and ensures continuous operation regardless of vacuum level. The Stokes 61B 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: 

• GV Drystar or Chemical Drystar dry pumps
• Two stage LR series liquid ring pumps
• RV, EM or EVC oil sealed pumps
• Microvac series piston pumps

Features & 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: 

Displacement
V belt (2750 rpm)	3375m3h-1 / 2000ft3min-1
Direct drive (1800 rpm)	2210m3h-1 / 1300ft3min-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	10/25hp
By-pass available	Yes
Cooling method	Air cooled
Oil capacity (horizontal flow)	1.9 litre / 0.51gal
Oil capacity (vertical flow)	4.1 litre / 1.1gal
Max temp rise	135°C / 275°F
Max discharge temp	191°C / 375°F
Weight bare shaft	284kg / 625lbs
Weight TEFC direct drive	530kg / 1170lbs