Roots-type blowers

Many users consider rotaiy compressors, such as the Rootes -type blower, as turbomachines because their behavior in terms of the rotor dynamics is very close to centrifugal and axial flow machineiy. Unhke the reciprocating machines, the rotary machines do not have a veiy high vibration problem but, like the reciprocating machines, they are positive displacement machines. 

Limited operating pressures (e.g., 80 to 100 kPag for Roots-type blowers)... 

The agglomerator is shown in the partial sectional view in Figure 7 and the system is shown in Figure 8. Starting from the left we have the 600 acoustic watt siren designed and built at Penn State. Compressed air is provided by a Roots-type blower. Pressure to the siren is controlled by means of a bypass valve. 

Pneumatic conveying is frequently a cost effective option, using a Rootes-type blower and a rotary blowing seal. Alternative proprietary units are available. Pipelines should normally have a nominal bore of at least 50 mm and bends should have a radius of at least 1 m. The reception hopper should be fitted with an air-pressure relief valve. Powder pumps are also used successfully. They tend to use less air than pneumatic conveying systems. 

Use root-type blower instead of centrifugal blower for getting steady air flow which is necessary for smooth plant operations. 

Precaution—Use a Roots-Type Blower with Variable Frequency-Driven Motor... 

Figure 12-108. Typical performance curve for lobe-type blower. (Used by permission 1961. Roots Division Dresser Industries, Inc.)...

Evacuation of the chamber is achieved by means of a series of pumps initially a rotary piston pump takes the pressure down from atmospheric to around 30 Torr, then a blower of the Rootes-type reduces it further to about 0.1 Torr lastly, an oil-diffusion pump brings the chamber down to the condition required for the evaporation cycle—in the region of 0.0002 Torr. 

Figure 6-43. Screw-type rotors for rotary lobe blower. By permission. Roots Division, Dresser Industries, Inc.

Roots blower A type of low-gauge pressure compressor for the transport of large volumes of gas. It consists of two rotating lobe-type to tots that have a small clearance between the rotors and the casing. It is named after its American inventor Francis Roots (1824-89) and his brother Philander (1813-79), who founded the Roots Blower Company. 

Blower (vacuum technology) A low compression mechanical, compression-type vacuum pump. Example Roots blower. 

Roots blower (vacuum technology) A compression-type mechanical pump that uses lobeshaped interlocking rotors to capture and compress the gas. The roots pump uses tight mechanical tolerances for sealing (no oil) and so is sometimes classed as a dry pump. See also Vacuum pump. 

---