Positive Displacement Lobe Pumps

Is a LobeStar rotary pump right for you?

1. Are you pumping sludge, mud or slurry?
2. Does your application require a pulse free or low shear flow?
3. Does your application require self-priming suction lift or a strong vacuum?
4. Are you pumping a mixture of air and fluid?

If you answered yes to just one of the above questions, then you could possibly benefit from a LobeStar pump. LobeStar rotary lobe pumps are members of the positive displacement pump family and are ideal for agricultural, industrial and municipal applications.

Lobestar Pumps Versus Centrifugal Pumps

LobeStar Pumps are effective replacements for centrifugal pumps in sludge and slurry applications because they are more forgiving. Centrifugal pumps are adversely affected by entrained air, by inadequate Net Positive Suction Head (NPSH) or if not operated within 10% of their best efficiency point. Operating centrifugal pumps in excess of 10% their best efficiency point causes shaft deflection, vibration and cavitation, which damages internal parts and reduces the effective life of the pump.

Rotary Lobe Pumps will happily pump air and water, will not cavitate as a result of inadequate NPSH and are equally efficient at all points within their operating range. Unlike centrifugal pumps, the output of positive displacement pumps are largely unaffected by head or viscosity.

Wear rates in abrasive applications are greatly affected by pump RPM’s. As pump RPM’s increase, relative wear rates increase exponentially. This is why LobeStar engineers are involved in every aspect of pump selection. LobeStar engineers will specify the proper pump and speed requirement for your application ranging from 200-300 RPM’s for abrasive applications to 500-600 RPM’s in non abrasive applications. Contrast this for wear rate to centrifugal pumps which commonly operate at 1750 RPM’s. This difference in pump speed has the added result that centrifugal pumps mix and agitate the fluids pumped whereas rotary pumps operated at low RPM and gently transfer the fluid with low shear flow.

Another significant difference is rotary lobe pumps create a strong vacuum which brings the material to the pump and makes them self priming without having to separate air from fluid. Centrifugal pumps must have a separate priming mechanism to separate air from water in order to self prime. This mechanism is easily clogged by solids or viscous materials. Centrifugal pumps do not bring the material to the pump.

LobeStar Pumps Versus Progressive Cavity Pumps

LobeStar pumps can be used in most transfer processes involving thick or thin sludge, mud and slurries. They have the following advantages over progressive cavity pumps:

1. Ability to run dry for a period of time
2. Sharply lower maintenance and repair cost.
3. Require approximately 1/3 their physical space. In addition, progressive cavity pumps need additional space for removing the rotor and stator.
4. As an added benefit, LobeStar rotary pump lobes, seals and wear plates can be replaced without removing attached piping.

How Do Rotary Lobe Pumps Work?

Lobestar rotary pumps are positive displacement pumps. A positive displacement pump operates by trapping a fixed amount of fluid from an intake pipe and then forcing (displacing) that trapped volume into a discharge pipe.

1. To displace the pumped material, LobeStar pumps utilize intermeshing helical lobes mounted on parallel shafts. The shafts are rotated by timing gears.
2. As the lobes un-mesh on the intake side, they create a cavity with an expanding volume. Your sludge or slurry flows into the cavity and is trapped by the lobes as they rotate.
3. The sludge or slurry then travels around the interior of the casing in the void between the lobesand the housing segments. The pumped material does not pass between the lobes.
4. As the lobes begin to mesh on the discharge side, the lobes force the sludge or slurry through the outlet port under pressure. The capacity of material being pumped can be changed by varying speed of the rotary pump.

LobeStar pump model numbers correspond to the volume pumped per 100 revolutions. For instance, the RM100 can pump 100 GPM per 100 revolutions or 1 gallon per RPM.