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Apr 21, 2022 View:

What is a lobe pump?

Rotor pumps are divided into gear pumps, screw pumps, rotary piston pumps (lobe pumps, Roots pumps), flexible impeller pumps, sliding vane pumps, hose pumps, etc. according to the structure type.


(1) Gear pump

lobe pump
Gear pumps mainly have gears, shafts, pump bodies, pump covers, bearing sleeves, shaft seals and other components. Relying on the pump body and the working volume formed between the meshing gears change and move to transport the liquid or make it pressurized rotary pump. Gear pumps have two types of structure: external and internal. External gear pumps are divided into double gear pumps, three gear pumps and five gear pumps, and external double gear pumps are most commonly used. A pair of intermeshing gears and the pump body separates the suction chamber and the discharge chamber. When the gears rotate, the volume between the teeth on the side of the suction chamber where the teeth are separated from each other gradually increases, the pressure decreases, and the liquid enters between the teeth under the action of differential pressure. With the rotation of the gear, the liquid between the teeth is brought to the discharge chamber. At this time, the volume between the teeth at the engagement of the teeth on the discharge chamber side gradually decreases, and the liquid is discharged.

(2) Screw pump

The screw pump consists of a pump casing and one or more screws. The working principle of twin-screw pumps is very similar to that of gear pumps, which relies on the mutual meshing of the screw to suck and send the liquid. Screw pumps are divided into single screw pumps, twin screw pumps and triple screw pumps according to the number of screws, among which twin screw pumps are of two types: closed and non-closed.

(3) Rotary piston pump

Rotary piston pumps have a wide variety of structures, the most commonly used of which are lobe pumps, Roots pumps and so on.
Lobe pump is a multi-purpose bi-directional volume pump, one of the most advanced fluid transfer equipment in the international arena. It uses two rotors with synchronous motion, the rotors are driven by a pair of external synchronous gears, the rotors are driven by the drive shaft for synchronous counter-directional rotation, the rotors do not contact each other and between the rotors and the pump body, but form a gap line or face seal, thus constituting a high vacuum and discharge pressure. It is especially suitable for food, medicine, corrosive and high viscosity media.
Roots pump and lobe pump structure form similar, the difference is that the liquid seal also to form between the rotor, large pumps are mostly simple support arrangement, it is simpler processing than lobe pump, working pressure is lower than lobe pump.

(4)Flexible impeller pump

Flexible impeller pump is a volumetric rotor pump. The flexible impeller pump consists of a flexible impeller made of rubber, pump body, mechanical seal and rotating shaft. When the impeller rotates away from the eccentric section of the pump casing, the flexible impeller vane straightens to produce vacuum, and the liquid is sucked into the pump, and as the impeller rotates, the liquid then reaches the discharge side from the suction side, and when the impeller vane comes into contact with the eccentric section of the pump casing, the working volume changes and the liquid is discharged out of the pump smoothly.

(5) Sliding vane pump

The rotor with radial groove is installed in the pump body with eccentric stator, the slide is located in the radial groove of the rotor, the slide can be two or more pieces, when the rotor rotates under the action of centrifugal force, the slide is thrown out from the rotor body, sliding along the inner surface of the stator. These slips and the stator constitute a sealed cavity with the eccentric increase in cavity gradually increase, continue to rotate, the cavity is reduced to zero, and filled in the rotor, the cavity between the slips liquid began to suck in from the suction area, and then pressed to the discharge area to complete the liquid transfer process.

Selection points

Centrifugal pumps account for about 80% of all pumps in industrial production, and rotor pumps account for about 10%. Therefore, users are generally more familiar with centrifugal pumps, but also more preferential. This often causes in some occasions not suitable for the use of centrifugal pumps in the choice of centrifugal pumps.
Generally speaking, for a variety of different viscosity of the liquid transport, rotor pumps have other pumps incomparable advantages, but in the liquid transport, not only the viscosity of the problem, and often accompanied by high temperature, high pressure and sometimes corrosive, or contain solid particles characteristics. For this reason, in the selection of rotor pumps, the following requirements must be considered.
1) the flow of the transported liquid, the selected pump for the viscosity of the applicable range.
2) the occasion of the metering requirements, the selected pump in viscosity and other process conditions change performance stability.
3) the back pressure of the system, the selected pump pressure applicable range.
4) Suction performance, high viscosity when the pumping performance.
5)High temperature resistance, corrosion resistance, etc.
6) Simple structure, easy to disassemble, cleaning and maintenance, etc.
In addition to this, in the selection of pump type must also consider the nature of the transported liquid, for the lack of lubrication of the liquid, the pump is required to have a certain gap or make the contact surface is small, because under load to avoid excessive friction and wear, the lack of lubrication of the liquid can not be shaped into an oil film; for the liquid containing grinding solids, the selection should consider the transport of solid particles in suspension does not cause jamming or excessive wear; for With soft solid particles of liquid, the selection should consider the pump has a suitable gap for such solid particles, not resulting in particle damage; for shear stress-sensitive liquid, the selection should consider the pump has a gentle action, and make the liquid is not high local shear stress. Usually choose a lower speed pump.


Also known as colloid pump, lobe pump, triple lobe pump, universal transfer pump, etc., the rotor pump is a volumetric pump. It is to achieve the purpose of conveying fluid with the help of the periodic transformation of multiple fixed volume conveying units in the working chamber. The mechanical energy of the motor is directly transformed into the pressure energy of the conveyed fluid through the pump, and the flow rate of the pump depends only on the value of the change in the volume of the working chamber and its frequency of change per unit time, and (theoretically) has nothing to do with the discharge pressure; the rotor pump actually works through a pair of synchronously rotating rotors. The rotor has a pair of synchronous gears inside the box for transmission, and the rotor is driven by the main and secondary shafts to rotate in the opposite direction synchronously. The volume of the pump is made to change, thus constituting a higher vacuum and discharge pressure. It is especially suitable for the transportation of sanitary medium and corrosive and high viscosity medium. The specific working principle can be seen in the working principle diagram.
Rotor pump is a form of volumetric pump. It consists of a rotor and a stationary pump body. It has no suction and discharge valves, and changes the working volume through the relative movement between the rotor and the pump body, and discharges the liquid by the squeezing effect of the rotor, while leaving space on the other side to form a low pressure, so that the liquid is continuously sucked in.
According to its structure and principle, the rotor pump can be divided into gear pump, screw pump, rotary piston pump (lobe pump, Roots pump), flexible impeller pump, sliding vane pump, hose pump, etc. Rotor pump is a rotating volumetric pump, with positive displacement nature, its flow does not change with the change of back pressure.
Preferred occasions for rotor pumps are: viscous liquids, occasions requiring metering, occasions requiring self-priming, occasions containing gases, small flow occasions, pumps requiring no shearing of the medium, high pressure occasions requiring reversal of the pump, etc.


The whole assembly of the coupling makes the volume smaller (the length can be shortened by 100-250mm), reducing the floor space, compact structure, stainless steel outer package, mirror polishing, beautiful appearance, high grade, avoiding the original paste painting off. Performance optimization: the use of coupling overall assembly, reduce the elastic coupling power consumption, noise and wear and tear replacement and improve efficiency, to get the highest efficiency, the smallest internal sliding and longer service life.


working principle

The rotor pump relies on two rotors (2-4 teeth) that rotate in reverse synchronously to generate suction (vacuum) at the inlet during the rotation, thereby drawing in the material to be conveyed. The two rotors separate the rotor chamber into several small spaces and operate in the sequence a→b→c→d. When running to position a, only the I chamber is full of media; to position b, the B chamber is closed part of the media; to position C, the A chamber is also closed media; to position d, the A chamber B chamber is connected with the II chamber, the media is transported to the discharge port. So the cycle is repeated, the medium (material) that is constantly transported out.


1. Food and beverage: dairy products, latex, chocolate, syrup, cheese, wort, beer, soft drinks
2. Fruit concentrates: pudding, jam, jelly, ketchup
3. Paste products: fats and oils, etc.
4. Cosmetics: creams, detergents, hair gels, fragrance oils, etc.
5. Pharmaceuticals: infusions, emulsions, pills, etc.
6.Chemical industry: dyes, fats, solvents, resins and polymers


Technical parameters

1. Flow rate: Q=200L/hour~400,000L/hour
2、Viscosity range of conveyed material: 1CP~1000,000CP
3. Maximum outlet pressure: 0.1-1.2Mpa (in high viscosity), special configuration can reach 1.6Mpa
4. Product temperature: room temperature (special requirements must be specified)



1. All parts and components in the rotor pump that come into contact with the conveyed materials are made of stainless steel materials that meet sanitary standards, and its seals are made of non-toxic rubber. Reliable rust resistance and non-toxic sealing ensure safety and hygiene.
2. The streamline structure of the rotor and the absence of dead spots and non-metal parts in the rotor chamber avoid contamination of the conveyed material.
3. Suitable for in-situ CIP cleaning and steam sterilization, fully complying with the requirements of the U.S. FDA specifications and pharmaceutical grade (GMP) specifications.

4. It is especially suitable for the process of conveying foam easily and conveying high viscosity, high concentration and any media containing particles, and the material conveyed by it keeps the original quality and does not have any physical and chemical reaction.
5. Adopt external movable and static ring mechanical seal, which can be flushed by water directly, resistant to high pressure, not easy to wear, no leakage.
6. Small volume, large flow, high head pressure, suitable for long distance and high resistance quantitative conveying.
7. The impeller and transmission gear of the pump are separated, and the gap between the parts in the pump cavity is ensured, no contact with each other, no wear and tear, low noise, good reliability, long service life, energy saving and consumption reduction.
8. After configuring the frequency converter, the flow rate can be adjusted at will, and can be used as a general metering pump.
9. It can convey three-phase mixture of steam, liquid and solid materials. The viscosity of the medium that can be conveyed can be as high as 1000000CP and the slurry with solid content up to 55%.
10. Compact structure, easy maintenance, almost no wearing parts, low cost of operation.
The common features of various rotor pumps are as follows.
①No suction valve and discharge valve, their main working parts are pump casing and rotor (such as gear, screw, cam, etc.).
②Compared with reciprocating pumps, the rotor makes rotary motion, no impact, higher speed, compact structure and smaller volume.
③Discharge pressure is generally higher, but lower than the reciprocating pump, the flow is smaller than the reciprocating pump, lower efficiency, generally only suitable for conveying small amounts of liquid, and mostly used as auxiliary equipment.
④Most of the rotor pump is dependent on its own transport of liquid lubrication, so it is generally suitable for the transport of lubricity and does not contain solid particles of liquid.
⑤The rotor pump is also intermittently discharging liquid, so the fluctuation of flow is larger than centrifugal pumps and smaller than reciprocating pumps, but can be seen as approximately uniform.
⑥When a liquid film exists on the rotor surface (conveying lubricious liquid), the pump will have self-priming capability.


1 Installation of coupling
When installing the coupling, it must be pressed into the drive shaft through the threaded hole at the end of the drive shaft with a special tool, and the coupling must not be struck with a hammer.
2 Alignment of pump drive shaft and motor
The maximum tolerance range of different shaft degrees allowed for the two couplings (standard installation).
--radial offset: 1% (maximum outside diameter)
--Deflection angle: ≤ 1°30´
For pump assembly (including drive unit and base), after the factory has been adjusted and the pump is installed on the foundation, the coupling cover should be removed to check the coaxiality of the pump shaft and the drive shaft (if the foundation is not level and the base pawn is bent after installation, it will cause great danger).
3 Rotation direction
The direction of rotation of the pump is indicated on the label, and the direction of rotation of the pump determines the direction of media delivery. If you need to change the direction, you must get the consent of the manufacturer or supplier.
4 Pressure
The pressure of the pump has been tested and marked on the nameplate before the pump leaves the factory, the user must consider the pressure of the pump and the surrounding accessories system when selecting the pump.
5 Piping system
When stopping operation, a certain amount of medium should be retained in the piping connected with the discharge body and suction chamber to lubricate the sealing device when starting, or flush the mechanical seal with water.
Before the installation of the pump, clean the piping connected with the pump.
It must be ensured that no additional force is applied to the pump body after connecting the piping on. That is, when connecting the pipeline down the inlet and outlet to ensure that it does not affect the pump and the base connection bolts.
Must ensure that the vibration of the pipeline has no danger of damaging the pump body.
6 Shaft seal
Must regularly check the shaft seal and O-ring, if wear damage or aging will be replaced in a timely manner, the required additional parts can be contacted with the manufacturer or consulting.
7 Connect the electricity
Electrical work must be carried out by electrical technicians in accordance with the relevant regulations.

Precautions and operating procedures for rotor pumps

I. Precautions before starting.
Check whether the oil quantity in the gear box is normal, observe the transparent oil mark, the oil stock should be half of the oil mark sight window, the lubricant should be replaced regularly, normally, all should be replaced after 4000 hours of operation.
Open all the inlet and outlet valves of the pipeline before starting, when the medium flows into the cavity, no abnormality after turning the pump by hand, you can first point, confirm the pump steering and medium flow before starting the official operation, it is strictly prohibited to run empty pump. When the pump reaches the normal speed, the
Observe the pressure indicator of the pump.
When the pump installation position has suction range requirements, should be filled with material in the pump inlet pipe and pump cavity.
When the process requires heating or cooling of the medium, the heating or cooling device should be opened before the pump is turned on, half of the heating energy should be opened 10 minutes in advance, and then the pump should be turned on.
Mechanical seal pump equipped with cooling water, the cooling water must be turned on before starting, and to ensure that there is no disconnection after starting, otherwise the mechanical seal is damaged immediately.
Second, operation
1, the pump in the process of operation, should pay attention to the motor power and pump operation, there are abnormalities should stop the pump to find the cause.
2, the mechanical seal should be no leakage, heat phenomenon.
3, the pump with packing seals, allow 1 ~ 3 drops per minute, such as leakage increases slightly tighten the material ring can be, no need to disassemble.
4、When mechanical stepless transmission is used, the speed is gradually adjusted according to the speed displayed in the digital display after the machine is turned on, and it is strictly forbidden to rotate the speed regulating disk when it is stopped, otherwise the induction reducer will be damaged.
5, the use of inverter speed regulation can use manual frequency regulation and automatic control of two methods.
6, often check the heat of the pump and motor, when the pump is in the water-cooled state, the bearing temperature rise is 40 ℃. When the pump is in the hot water insulation state, the bearing seat temperature is allowed to be 30℃ higher than the pump body temperature.
7, can not use the valve of the inlet pipeline to adjust the flow, to avoid cavitation and cause vibration of the pump.
8、When the pump is running, it is forbidden to close all the inlet and outlet valves.
Third, stop
1, stop the pump to close the import and export valves, easy to condense material discharge cleanup.
2, the pump after a long period of time out of use, before starting should first turn the coupling by hand, feel the resistance, but can turn at will and light and heavy uniform. And pay attention to identify whether there is friction sound and foreign matter in the pump.
3, in the pump and the reducer motor re-installation, should check the coaxiality of the pump shaft and the motor shaft, measuring the coupling of the outer circle of the upper and lower left and right piece position not more than 0.1mm, otherwise it will cause the pump vibration, affect the spindle life.


(1) Check the rotor pump and pipeline and the combination of any loose phenomenon. Rotate the rotor pump by hand and try to see if the rotor pump is flexible.
(2) Add bearing lubrication oil to the bearing body, observe the oil level should be at the center line of the oil mark, the lubricant should be replaced or replenished in time.
(3) unscrew the pump body of the rotor pump draw plug, fill the draw water (or draw slurry).
(4)Close the gate valve of the outlet pipe and export pressure gauge and import vacuum gauge.
(5)Start the motor and try to see if the motor steering is correct.
(6)Start the motor, when the rotor pump is running normally, open the outlet pressure gauge and the inlet vacuum pump, and gradually open the gate valve after it shows the proper pressure, and check the motor load at the same time.
(7) Try to control the flow and head of the rotor pump within the range indicated on the label to ensure that the rotor pump operates at the highest efficiency point in order to obtain the maximum energy saving effect.
(8) During the operation of the rotor pump, the bearing temperature should not exceed the ambient temperature of 35C and the maximum temperature should not exceed 80C.
(9) If abnormal sound is found in the rotor pump, it should be stopped immediately to check the cause.
(10) When the rotor pump is to be stopped, close the gate valve and pressure gauge first, then stop the motor.
(11) Rotor pump in the first month of work, after 100 hours to replace the lubricant, after each 500 hours, change the oil once.
(12) Adjust the packing gland frequently to ensure that the drip inside the packing chamber is normal (to become a drip leak out as appropriate).
(13) Regularly check the wear and tear of the shaft sleeve, and replace it in time after the wear and tear is large.
(14) rotor pump in the winter season, after parking, the pump body needs to be unscrewed lower water release screw to release the media net. Prevent freezing and cracking.
(15) rotor pump for a long time out of use, the pump need to be completely disassembled, dry water, the rotating parts and combined with grease installed, properly stored.
Commonly used model: nyp internal ring high viscosity rotor pump

Use introduction

NYP series internal gear pump is a new type of volumetric rotor pump developed according to the special needs of petroleum, chemical, coating, grease, pharmaceutical, fuel, food and other industries, and its biggest feature is that it can be used to transport ultra-high viscosity liquid or even semi-solid material. The suitable temperature of medium is: -10℃~200℃, and the suitable viscosity of medium is 1cst~3000000cst. by going because the product can choose different materials and its unique structure, so it is widely used in different nature and different viscosity of medium transportation.

Structure description

The pump is mainly composed of inner and outer rotor, shaft, pump body, front cover, bracket, seal, bearing, etc. There are two forms of mechanical seal and packing mechanical seal, for high temperature, high viscosity and corrosive media, the packing seal is selected. When conveying easy to crystallize materials, in the front cover and pump body can be designed with insulation jacket, work through steam insulation melting, the pump can be equipped with a safety valve, when the pump or management system overpressure, the safety valve open, the formation of internal reflux, to ensure the safety of the system, the pump device by the pump, motor good base composition, the transmission mode has a bridge and direct connection type two. From the motor end to this look, for clockwise rotation.
NYP internal ring type high viscosity rotor pump has the advantages of smooth transmission of liquid, no pulsation, small vibration, low noise, etc. It has strong self-priming, and the corresponding raw materials can be selected to convey corrosive media, and the use temperature can reach 200℃. Rotor wear is small so that the pump life is long, can change the speed to change the pump flow and other advantages.

Main matters

(1)The lubricity, cleanliness and corrosiveness of the medium.
(2) The viscosity of the medium, temperature.
(3) The import and export pressure of the pump, installation height.
(4) Explosion-proof requirements of the use occasion
(5) When ordering, please specify the pump model, design pressure, speed, medium viscosity, temperature, motor explosion-proof level, medium name.
(6)For the special working conditions other than this sample, we can design and supply separately according to the user's requirements.