Lubrication for Rotary Lobe Blowers

Roots Synthetic lubricant oil and greaseProper lubrication is the key to long life for your blowers.The Roots Universal RAI® series utilizes grease on the drive end and oil on the gear end. The vast majority of remaining Roots products utilize oil on the gear and drive end.

Oil Lubrication

Synthetic lubricants provide the longest life between oil change intervals and should be used wherever practical. Oils must be premium grade and non-detergent with rust, oxidation, and foam inhibitors.

The recommended oil for all Roots’ products is ROOTS™ Synthetic Oil which is superior in performance to petroleum based products. It has high oxidation stability, excellent corrosion protection, extremely high film strength and a low coefficient of friction. Typical oil change intervals are increased 2-3 times over petroleum based lubricants. Another important property is it is 100% compatible with petroleum based oils. Simply drain the oil in the blower and refill the reservoirs with ROOTS™ Synthetic Oil to maintain optimum performance.

Oil viscosity is dependent on the expected ambient conditions surrounding the blower and driver. Note: Ambient temperature is the temperature in the space the blower is located, not the outside air temperature.

The required viscosity is as follows:

Splash Lubricated Blowers

  • Ambient Temperature 90°F to 120°F (32°C to 48°C) use ISO Viscosity No. 320
  • Ambient Temperature 32°F to 90°F (0°C to 32°C) use ISO Viscosity No. 220
  • Ambient Temperature 0°F to 32°F* (-18°C to 0°C) use ISO Viscosity No. 150
    (This is an uncommon grade and VG-100 or VG-200 can be substituted. See manual for more detail)
  • Ambient Temperature below 0°F* (-18°C) use ISO Viscosity No. 100

Pressure Lubricated Blowers

  • Ambient Temperature 32°F to 120°F (0°C to 48°C) use ISO Viscosity No. 220
  • Ambient Temperature 0°F to 32°F* (-18°C to 0°C) use ISO Viscosity No. 100

*Oil is to be heated to 60°F prior to starting the blower

The oil should be changed after the initial 100 hours of operation.

Effect of temperature on blower oil life infographicNormal life expectancy of petroleum based oils is about 2000 hours with an oil temperature of about 180°F (82°C). As the oil temperature increases by increments of 15 to 18°F (8°C to 10°C), the life is reduced by half.  Normal expectancy of ROOTS Synthetic Oil is about 4000 to 8000 hours with an oil temperature of about 180°F (82°C). As the oil temperature increases by increments of 15 to 18°F (8°C to 10°C), the life is reduced by half.

The oil temperature may be estimated by multiplying the discharge temperature of the air or gas stream by 0.8. As an example, if the discharge air temperature of the blower is 200°F, it is estimated that the oil temperature is 160°F.

Grease Lubrication

For the Roots Universal RAI® blowers that utilize grease in the drive end, there are two primary types of grease that may be used, depending on which unit you have: a clay-based Shell grease and a synthetic Roots grease. Old Roots product manuals recommended the clay-based Shell Darina grease for general use (note: Shell has replaced the Darina grease with Gadus grease) and a NLGI Grade 2 premium grade aluminum complex grease for gas applications. Starting in fall of 2016, Roots standardized and began using synthetic grease on all units. If you have a new unit (look for a serial number starting with 16 followed by a letter) it will use the purple Roots synthetic grease. Older units could use either, but it is important to note that the two types of grease cannot be mixed as they will separate and no longer provide proper lubrication for your blower.

To maintain your Roots blower, you should continue using the same type of grease your blower has now. A quick visual inspection should help you identify your grease: Shell grease has a tan color and Roots synthetic grease is purple. Click here for more information on which type of grease to use with your blower.

Note: Lithium based greases are not approved for use with ROOTS™ blowers.

Roots grease - synthetic vs clay

Roots recommended greasing intervals

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