ATOS gear pump malfunctions and repairs

Brand

ATOS/Italian Atos

ATOS proportional valves, ATOS stack valves, ATOS solenoid valves, ATOS amplifiers, ATOS solenoid directional valves, ATOS pressure reducing valves

During operation, ATOS gear pumps sometimes fail to meet production requirements, necessitating performance adjustments. For example, during winter's low water levels or summer's flood season, changes in the water level of the inlet or outlet pool alter the actual terrain's pumping height. The originally determined head and flow rate become unsuitable, leading to reduced efficiency and uneconomical pump operation. Therefore, to ensure the pump meets new requirements while operating at higher efficiency, performance adjustments to the gear pump are necessary.

1) Fault phenomenon: Pump cannot discharge material. Fault causes: a. Reverse rotation direction; b. Inlet or outlet valve closed; c. No material at the inlet or low pressure; d. Viscosity too high, pump cannot bite material.

Solutions: a. Confirm rotation direction; b. Confirm valve is closed; c. Check valve and pressure gauge; d. Check liquid viscosity, whether the flow rate proportional to the speed appears when running at low speed. If there is flow, the inflow is insufficient.

(2) Fault phenomenon: Insufficient pump flow.

Fault causes: a. Inlet or outlet valve closed; b. Low inlet pressure; c. Outlet pipeline blockage; d. Packing box leakage; e. Speed ​​too low.

Solutions: a. Confirm valve is closed; b. Check valve is open; c. Confirm discharge rate is normal; d. Tighten; if a large leakage affects production, stop operation and disassemble for inspection; e. Check actual pump shaft speed;

(3) Fault phenomenon: Abnormal sound.

Fault causes: a. Coupling misalignment or poor lubrication; b. Motor failure; c. Reducer abnormality; d. Improper installation of shaft seal; e. Shaft deformation or wear

Solutions: a. Alignment or filling with grease; b. Check the motor; c. Check the bearings and gears; d. Check the shaft seal; e. Disassemble and inspect after stopping

(4) Fault phenomenon: Excessive current

Causes of fault: a. Excessive outlet pressure; b. Excessive melt viscosity; c. Improper shaft seal fitting; d. Shaft or bearing wear; e. Motor failure

Solutions: a. Check downstream equipment and pipelines; b. Check viscosity; c. Check shaft seal and adjust appropriately; d. Check after stopping, manually rotate the pump to check for excessive force; e. Check the motor

(5) Fault phenomenon: Pump suddenly stops

Causes of fault: a. Power outage; b. Motor overload protection; c. Damaged coupling; d. Excessive outlet pressure, interlock reaction; e. Abnormal entrainment inside the pump; f. Shaft and bearing stuck together Countermeasures: a) Check the power supply; b) Check the motor; c) Open the safety cover and check by rotating the pump; d) Check the instrument interlock system; e) After stopping, check by rotating the pump in both forward and reverse directions; f) Check by rotating the pump

1) Fault phenomenon: The pump cannot discharge material. Fault causes: a) Reverse rotation direction; b) Inlet or outlet valve closed; c) No material at the inlet or low pressure; d) Viscosity too high, the pump cannot bite the material

Countermeasures: a) Confirm the rotation direction; b) Confirm whether the valve is closed; c) Check the valve and pressure gauge; d) Check the liquid viscosity, and whether the flow rate proportional to the speed appears when running at low speed. If there is flow, the inflow is insufficient.

(2) Fault phenomenon: Insufficient pump flow

Fault causes: a) Inlet or outlet valve closed; b) Low inlet pressure; c) Blocked outlet pipeline; d) Leaking stuffing box; e) Low speed

Countermeasures: a) Confirm whether the valve is closed; b) Check whether the valve is open; c) Confirm whether the discharge volume is normal. d. Tighten; if a large amount of leakage affects production, the pump should be stopped and disassembled for inspection; e. Check the actual speed of the pump shaft;

(3) Fault phenomenon: abnormal sound

Fault cause: a. large eccentricity of the coupling or poor lubrication b. motor failure; c. abnormal reducer; d. poor installation of the shaft seal; e. shaft deformation or wear

Countermeasures: a. Align or fill with grease; b. Check the motor; c. Check the bearings and gears; d. Check the shaft seal; e. Stop the pump and disassemble for inspection

(4) Fault phenomenon: excessive current

Fault cause: a. excessive outlet pressure; b. excessive melt viscosity; c. poor shaft seal fit; d. shaft or bearing wear; e. motor failure

Countermeasures: a. check downstream equipment and pipelines; b. check viscosity; c. check the shaft seal and adjust it appropriately; d. check after stopping the pump and manually rotate the pump to check if it is too heavy; e. check the motor

(5) Fault phenomenon: pump suddenly stops

Fault cause: a. power outage; b. motor overload protection; c. Damaged coupling; d. Excessive outlet pressure, interlock reaction; e. Abnormal pump engagement; f. Shaft and bearing stuck together.

Solutions: a. Check power supply; b. Check motor; c. Open safety cover and manually rotate the pump; d. Check instrument interlock system; e. After stopping, manually rotate the pump in both forward and reverse directions to confirm; f. Manual rotation confirmation.

ATOS gear pump performance adjustment typically employs two methods:

1. Speed ​​Variable Adjustment: We know that axial flow pumps operate at a certain speed, obtaining corresponding flow rate, head, power, and efficiency. When the speed changes, its performance parameters also change accordingly, thus achieving the purpose of adjustment. If the axial flow pump is powered by a diesel or gasoline engine, the speed can be changed by altering the throttle position; if the axial flow pump is connected to the power unit via a V-belt or flat belt indirect transmission device, the speed can be changed by altering the diameter of the transmission pulley. Replacing the drive pulley or driven pulley can also change the transmission ratio. Speed ​​variable adjustment of pump performance is relatively economical, has a wide range of applications, and can be used for all agricultural water pumps. Based on the impeller structure and blade installation angle, ATOS gear pumps classify blades into three types:

(1) Fixed blades: The blades and hub are cast as a single unit, and the blade installation angle is fixed during design and manufacturing and cannot be adjusted during use. This type of impeller is mostly used in gear pumps.

(2) Semi-adjustable blades: On the impeller hub, loosen the fixing nuts and positioning screws of each blade, adjust the blade installation angle to be consistent as required, and then tighten them. Generally, the blade installation angle is from -100° to 180°. Within this range, adjust according to usage requirements.

(3) Movable blades: The blades are adjusted using a specially designed angle adjustment mechanism. The blade installation angle can be changed directly by manipulating the mechanism without disassembling the impeller. The adjustment range is from 0° to 260°. There are two types of blade angle adjustment mechanisms: mechanical and hydraulic. This type of impeller is mostly used in large screw pumps. Structure and Principle of ATOS Gear Pumps

The structure of an ATOS gear pump is very simple. Its most basic form consists of two identical gears meshing and rotating within a tightly fitted housing. The housing's interior is shaped like an "8," housing the two gears with their outer diameter and sides tightly fitted to the housing. Material from the extruder enters the space between the two gears through the inlet, filling this space. As the gears rotate, the material moves along the housing and is finally discharged when the two gears mesh. Technically, a gear pump is also called a positive displacement device, much like a piston in a cylinder. When one gear enters the fluid space of another gear, the liquid is mechanically squeezed out. Because liquid is incompressible, the liquid and the gears cannot occupy the same space simultaneously, thus the liquid is expelled. Due to the continuous meshing of the gears, this phenomenon occurs continuously, providing a continuous discharge rate at the pump outlet. The discharge rate is the same for each pump revolution. As the drive shaft rotates continuously, the pump continuously discharges fluid. The pump's flow rate is directly related to its rotational speed. In reality, a small amount of fluid is lost within the pump, preventing it from reaching 100% efficiency. This is because the fluid is used to lubricate the bearings and gears, and the pump body cannot be perfectly flush, thus preventing 100% fluid discharge from the outlet. Therefore, a small amount of fluid loss is inevitable. However, the pump can still operate well, achieving 93%–98% efficiency for most extruded materials. This type of pump is not significantly affected by fluids whose viscosity or density varies during the process. If a damper is present, such as a filter or restrictor on the outlet side, the pump will force fluid through them. If this damper changes during operation—for example, if the filter becomes dirty or clogged, or the back pressure of the restrictor increases—the pump will still maintain a constant flow rate until the mechanical limit of the weakest component in the system is reached (usually equipped with a torque limiter).

ATOS gear pumps are a type of positive displacement pump, consisting of two gears, a pump body, and front and rear covers forming two enclosed spaces. When the gears rotate, the volume of the space on the disengaged side increases, creating a vacuum that draws in liquid. Conversely, the volume of the space on the meshing side decreases, forcing the liquid into the pipeline. The suction and discharge chambers are separated by the meshing line of the two gears. The discharge pressure of a gear pump depends entirely on the resistance at the pump outlet. A gear pump is a rotary pump that transports or pressurizes liquid by changing and moving the working volume between the pump cylinder and the meshing gears. The structure of an external meshing double gear pump: A pair of meshing gears and the pump cylinder separate the suction and discharge chambers. When the gears rotate, the volume between the teeth on the suction side gradually increases, the pressure decreases, and liquid enters the space between the teeth under the pressure difference. As the gears rotate, the liquid between each tooth is carried to the discharge chamber. At this point, the volume between the teeth on the discharge side gradually decreases, discharging the liquid. ATOS gear pumps are suitable for conveying lubricating liquids that are free of solid particles, non-corrosive, and have a wide viscosity range. The pump's flow rate can reach 300 m³/h, and the pressure can reach 3 × 10⁷ Pa. It is commonly used as a hydraulic pump and for conveying various oils. Gear pumps have a simple and compact structure, are easy to manufacture and maintain, and have self-priming capabilities; however, they experience significant flow and pressure pulsation and are noisy. Gear pumps must be equipped with a safety valve to prevent damage to the pump or prime mover caused by factors such as blockage of the discharge pipe, which could lead to the outlet pressure exceeding the permissible value.

The company mainly deals with European and American brands and can source brands from any European country. For example, our key German brands include: BURKERT, DEMAG, HAWE, REXROTH, HYDAC, PILZ relays, FESTO, IFM sensors, E+H, HEIDENHAIN, P+F sensors, SICK, TURCK, and HIRSCHMANN industrial switches. German brands: Hengstler, Murr, Schmersal, Samson, EPRO (Emerson Group)

American brands: MOOG, ASCO, MAC, NUMATICS, PARKER, VICKERS, ROSS

British brands: Norgren

Italian brands: OMAL, ATOS, CAMOZZI, UNIVER, Camozzi