Roots model 33 AF Blower
Flow Range: to 91 CFM
Max ΔPressure: 6 psi
Max ΔVacuum: 10″ Hg
Maximum Speed: 1850 RPM
Minimum Speed: 1090 RPM
Max ΔT: 190° F
Connection Size: 2″
Shaft Diameter: 0.6562″
Drive End Lubrication: Grease
Gear End Lubrication: Oil
Required Oil for Gear End: 6 Fl Oz
Unit Weight: 95 lb
The Roots rotary blower AF Series are now obsolete, replaced by the Universal RAI series. The 33 AF blower is typically replaced by the 33 URAI blower. Comparing these models, the inlet size, mounting feet diameter, and speed are the same, but the shaft size has changed from 0.6562″ on the 33 AF to 0.750″ on the 33 URAI.
The AF Series were standard duty units suitable for either pressure or vacuum service. The basic model is suitable for rotation in either direction consisted of a grey iron casing, alloy steel gears, grey iron impellers and anti-friction ball bearings. The unit has splash oil lubrication on the gear end and grease lubrication on the drive end.
By today’s standards, these units were operated very slow and were limited in maximum allowable pressure and vacuum.
Features that make the Roots rotary blower AF Series distinctive over the current Universal RAI are as follows:
- Mounting Feet are cast into the headplates versus removable mounting feet on current Universal RAI frames
- Cast iron gear housing versus cast aluminum on current Universal RAI’s
- The AF series is only available as a horizontal unit (vertical air flow) with a left hand shaft
- The unit will have a threaded inlet and discharge connection versus threaded as well as flanged connections on the current Universal RAI
- Shaft sizes on the 2″ through 5″ frames are an “odd ball” size – it will be difficult to find bushings to match these sizes
In general, you can determine the flow of the units below by multiplying the cfr by the RPM you are currently running then by 0.75. This will actually give you a close estimate when compared to the actual flow which takes into account slip inside the unit.