JN-5-B-1201
ROTARY LOBE PUMP JN-5-B-1201 OPERATING PRINCIPLES
Rotary lobe pumps are similar to external gear pumps in operation in that fluid flows around the interior of the casing. Unlike external gear pumps, however, the lobes do not make contact. Lobe contact is prevented by external timing gears located in the gearbox. Pump shaft support bearings are located in the gearbox, and since the bearings are out of the pumped liquid, pressure is limited by bearing location and shaft deflection.
1. The lobes, they create expanding volume on the inlet side of the pump. Liquid flows into the cavity and is trapped by the lobes as they rotate.
2. Liquid travels around the interior of the casing in the pockets between the lobes and the casing --it does not pass between the lobes.
3. Finally, the lobes forces liquid through the outlet port under pressure.
Rotary lobe pumps are frequently used in food applications because they handle solids without damaging the product. Particle size pumped can be much larger in rotary lobe pumps. Since the lobes do not make contact, and clearances are not as close as in other pumps, this design handles low viscosity liquids with diminished performance. Loading characteristics are not as good as other designs, and suction ability is low. High-viscosity liquids require reduced speeds to achieve satisfactory performance.
A=AXIAL clearance lobe / front cover
B=AXIAL clearance lobe / back side rotorcase
C=Radial clearance lobe / rotorcase top and bottom
D=Clearance lobe / lobe
Rotors in stainless steel clearances
| Pump Type | A | B | C | D |
| JN-1-L | 0.1±0.02 | 0.1±0.02 | 0.1±0.02 | 0.1±0.02 |
| JN-2-L | 0.125±0.03 | 0.125±0.03 | 0.1±0.03 | 0.1±0.03 |
| JN-3-L | 0.125±0.035 | 0.125±0.035 | 0.1±0.035 | 0.1±0.035 |
| JN-4-L | 0.15±0.04 | 0.15±0.04 | 0.12±0.04 | 0.12±0.04 |
| JN-5-L | 0.15±0.045 | 0.15±0.045 | 0.15±0.045 | 0.15±0.045 |