Everest Tri-Lobe Roots Blowers are positive displacement units. Their pumping capacity is determined by size, operating speed, and pressure conditions. It employs two Tri-Lobe impellers mounted on parallel shafts, rotating in opposite directions within a casing that is closed at both ends by side plates. As the impellers rotate, air is drawn into one side of the casing and forced out of the opposite side against the existing pressures. The differential pressure developed, therefore, depends upon the resistance of the connected system.
As positive displacement blowers, they do not generate pressure within the casing. The discharge pressure depends on the system's resistance or back pressure. The effective sealing of the compressor inlet area from the discharge area is achieved through very small operational clearances, eliminating the need for internal lubrication of the lobes. A pair of accurately machined alloy steel hardened, and ground timing gears maintain clearances between the impellers, during rotation.
The air, thus delivered, is 100% OIL FREE. The pumping capacity of a lobe compressor, operating at constant speed, remains relatively independent of inlet and discharge pressure variations. These Blowers are constant volume machines, which deliver a fixed discharge against the system back pressure. It is, therefore, essential to ensure that minimum pipeline restrictions, at the inlet and discharge, are imposed. Adequate size piping and large radius bends ensure minimum line losses resulting in higher efficiency and low power consumption. Sudden changes in pipeline cross section should also be avoided.
To change capacity, it is necessary either to change speed (energy saving) or vent some of the air into the atmosphere (not energy saving). The air must not be re-circulated from the discharge to suction as it may result in overheating of the tri-lobe blower. No attempt should ever be made to control the capacity of compressor by means of throttle valves in the intake or discharge piping. This increases the power load on the motor and may seriously damage the compressor. There is an increase in the discharge air temperature due to heat of compression. As a thumb rule the discharge air temperature increases @ 100C for every 0.1 Kg/cm2 of P above the inlet temperature.
