German Marzocchi pump Marzocchi model Marzocchi price

Marzocchi pumps are rotary pumps that transport liquids or increase their pressure by relying on the change and movement of the working volume formed between the pump cylinder and the meshing gears. Two enclosed spaces are formed by two gears, the pump body, and the front and rear covers. When the gears rotate, the volume on the disengaging side increases from small to large, creating a vacuum that draws in the liquid, while the volume on the meshing side decreases from large to small, forcing the liquid into the pipeline. The suction chamber and the discharge chamber are separated by the meshing line of the two gears. The pressure at the discharge port of the gear pump depends entirely on the magnitude of the resistance at the pump outlet.

Marzocchi pump structural features

1) Simple structure and low cost; 2) Low operational requirements and wide application; 3) The end covers and the spaces between the gear teeth form many fixed sealed working chambers, so it can only be used as a positive displacement pump. The gears adopt the new technology of double-circular-arc sine curve tooth profile, which was at an advanced international level in the nineteen-nineties. Compared with involute gears, its most prominent advantage is that there is no relative sliding on the tooth flank during meshing, resulting in no wear on the tooth surface, smooth operation, no fluid trapping, low noise, long service life, and high efficiency. This pump breaks free from the constraints of traditional design, bringing gear pumps into a new realm in terms of design, production, and use. The pump is equipped with a differential pressure safety valve for overload protection. The full return pressure of the safety valve is 1.5 times the rated discharge pressure of the pump. It can also be adjusted according to actual needs within the allowable discharge pressure range. However, this safety valve cannot be used as a pressure reducing valve for long-term operation; a pressure reducing valve can be installed separately if needed. The shaft end seal of this pump is designed in two forms: one is mechanical seal, and the other is packing seal, which can be determined based on specific operating conditions and user requirements.

Marzocchi pump drive unit

The gear pump is driven by an independent motor, which can effectively block upstream pressure pulsations and flow fluctuations. The pressure pulsation at the gear pump outlet can be controlled within 1%. Using a gear pump on an extrusion production line can increase the flow output speed and reduce the shear and residence time of materials in the extruder. External meshing gear pumps are the most widely used type of gear pump; generally, when referring to gear pumps, it usually means external meshing gear pumps. Its structure is shown in Figure 5-14, mainly consisting of the driving gear, driven gear, pump body, pump cover, and safety valve. The sealed space formed by the pump body, pump cover, and gears is the working chamber of the gear pump. The shafts of the two gears are respectively installed in the bearing holes on the two pump covers, with the driving gear shaft extending out of the pump body to be rotated by the motor. External meshing gear pumps have a simple structure, light weight, low cost, reliable operation, and wide application range. When the gear pump is working, the driving gear rotates with the motor and drives the driven gear to rotate accordingly. When the meshing teeth on the suction chamber side gradually separate, the volume of the suction chamber increases, the pressure decreases, and the liquid in the suction pipe is drawn into the pump; the sucked liquid is pushed by the gears in two paths within the tooth slots to the discharge chamber. After the liquid enters the discharge chamber, due to the continuous meshing of the teeth of the two gears, the liquid is squeezed and enters the discharge pipe from the discharge chamber. As the driving gear and driven gear rotate continuously, the pump can continuously suck in and discharge liquid. A safety valve is installed on the pump body; when the discharge pressure exceeds the specified pressure, the transported liquid can automatically push open the safety valve, allowing the high-pressure liquid to return to the suction pipe. Internal meshing gear pumps consist of a pair of mutually meshing internal gears, a crescent-shaped piece between them, and the pump shell. The function of the crescent-shaped piece is to separate the suction chamber from the discharge chamber. When the driving gear rotates, a partial vacuum is formed where the gears disengage, sucking liquid into the pump to fill the spaces between the teeth in the suction chamber, and then entering the discharge chamber in two paths along the inner and outer sides of the crescent-shaped piece. Where the teeth enter meshing, the liquid existing between the teeth is squeezed and sent into the discharge pipe. In addition to having self-priming capability and flow rate independent of discharge pressure, gear pumps have no suction or discharge valves on the pump shell, featuring simple structure, uniform flow, and reliable operation, but they have low efficiency, high noise and vibration, and are prone to wear. They are mainly used to transport various oils that are non-corrosive, free of solid particles, and have lubricating properties, with temperatures generally not exceeding 70 ℃, such as lubricating oil and edible vegetable oil. The general flow range is 0.045～30ms/h, pressure range is 0.7—20MPa, and operating speed is 1200—4000r/min.

Marzocchi pump troubleshooting

1) Fault phenomenon: Pump cannot discharge material. Fault causes: a, reverse rotation direction; b, suction or discharge valve closed; c, no material at inlet or pressure too low; d, viscosity too high, pump cannot bite material. Countermeasures: a, confirm rotation direction; b, confirm whether valves are closed; c, check valves and pressure gauge; d, check liquid viscosity to see if flow appears proportional to speed at low-speed operation; if there is flow, the inflow is insufficient. 2) Fault phenomenon: Insufficient pump flow. Fault causes: a, suction or discharge valve closed; b, low inlet pressure; c, outlet pipeline blocked; d, packing box leakage; e, speed too low. Countermeasures: a, confirm whether valves are closed; b, check whether valves are open; c, confirm whether discharge volume is normal; d, tighten; if massive leakage affects production, stop operation and dismantle for inspection; e, check the actual speed of the pump shaft. 3) Fault phenomenon: Abnormal sound. Fault causes: a, large coupling eccentricity or poor lubrication; b, motor fault; c, gearbox abnormality; d, improper installation at shaft seal; e, shaft deformation or wear. Countermeasures: a, align or fill with grease; b, check motor; c, check bearings and gears; d, check shaft seal; e, stop and dismantle for inspection. 4) Fault phenomenon: Excessive current. Fault causes: a, excessive outlet pressure; b, melt viscosity too high; c, improper assembly of shaft seal; d, shaft or bearing wear; e, motor fault. Countermeasures: a, check downstream equipment and pipelines; b, test viscosity; c, check shaft seal and adjust appropriately; d, check after stopping, manually turn to see if it is too heavy; e, check motor. 5) Fault phenomenon: Pump stops suddenly. Fault causes: a, power outage; b, motor overload protection; c, coupling damage; d, excessive outlet pressure, interlock reaction; e, abnormal biting inside the pump; f, shaft and bearing adhesion/seizure. Countermeasures: a, check power supply; b, check motor; c, open safety cover and check by manual turning; d, check instrument interlock system; e, after stopping, confirm by manual turning in forward and reverse; f, confirm by manual turning. 6) Fault phenomenon: Seal oil leakage. Causes: a, shaft seal not adjusted properly; b, sealing ring worn resulting in large clearance; c, dynamic and static ring friction surfaces of mechanical seal damaged; d, spring relaxation. Countermeasures: a, readjust; b, tighten gland bolts appropriately or replace sealing ring; c, replace dynamic and static rings or regrind; d, replace spring.

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