Maintenance Methods for 2XZ-C Rotary Vane Vacuum Pumps

 

 Rotary vane vacuum pumps, such as the 2XZ-C model, are widely used for their reliability and efficiency. However, like any mechanical equipment, they can experience issues that require proper maintenance. Here are some common problems and their troubleshooting methods:

1. 2XZ-C Rotary Vane Vacuum Pump Does Not Start

Before attempting to start the pump, it's crucial to assess the situation to avoid exacerbating the problem. The pump may either turn manually (hand-rotatable) or be completely jammed.

• Pump is hand-rotatable but does not start: Possible causes include:

  • Coupling malfunction.
  • Belt slippage.
  • Incorrect motor wiring.
  • Motor failure.
  • Power supply issues.

• Pump is not hand-rotatable or is difficult to turn: This could be due to:

  • Low pump start temperature, leading to high pump oil viscosity.
  • Excessive backflow of pump oil upon shutdown due to design flaws or excessive oil level (overfilling, condensation of water vapor in the pump, or water condensed in the exhaust pipe flowing back into the pump).
  • Foreign objects inside the pump (such as welding slag, oxides in the intake pipe; debris from pump parts like rotor spring; or rotor deformation causing jamming).
  • Parts seizure (including bushings, rotors, middle walls, pump covers, stators, bearings).

2. Pump Overheats

Pump overheating is defined when the highest oil temperature measured near the low-grade exhaust valve exceeds the specified value in the user manual. Elevated pump temperatures can lead to several issues:

• Significant reduction in pump oil viscosity.
• Increase in the saturation vapor pressure of the pump oil, resulting in higher ultimate pressure and decreased pumping efficiency.
• Accelerated aging of rubber components.
• Reduced operational reliability due to thermal expansion, especially in the clearance between the thickness direction of non-metallic vanes and the inner hole of the copper bushing.

Possible causes of pump overheating include:

• High ambient temperature around the pump.
• High inlet air temperature.
• Malfunction of the intake air cooling device.
• Continuous operation at high inlet pressure for prolonged periods.
• Insufficient cooling water flow in water-cooled pumps.
• Ineffective circulation water design or malfunction of the temperature control water flow regulating valve.

3. Failure to Reach Ultimate Pressure

The failure to reach the ultimate pressure could be caused by external leaks, internal leaks, clogged oil holes, poor or contaminated pump oil quality, the presence of water vapor or other condensable substances, inaccurate instruments, or abnormal pump operation.

• Signs of excessive external leakage: Visible white vapor at the exhaust port, excessive bubbles at the oil gauge, and noticeable exhaust pressure when placing a hand on the exhaust port. Additionally, bubbles may be present on the oil surface near the low-grade exhaust valve, potentially causing increased power consumption. In such cases, the first step is to check if the gas ballast valve is properly closed. External leaks can be caused by various factors, including:

  • Failure of the external shaft seal.
  • Absence of oil in the oil cup.
  • Gas leakage through the oil hole plug head.

• Internal leaks can result from gaps in moving parts inside the pump, flatness issues with the exhaust valve seat, sealing surfaces of the exhaust valve, internal shaft seals, pump cover flatness, intake pipe seals, and gas ballast valve seals. Wear, corrosion, and seizure can increase these operational gaps.

• Oil hole blockage: When blocked, the noise of the pump may decrease when the oil filler hole is opened. If the pump oil is clean and the pump has been idle for an extended period, opening the gas ballast valve may help remove water vapor from the pump. If this does not work, the gauge should be checked. If the pump oil turns yellow or white and emulsifies, the gas ballast can be fully opened, and the ballast flow can be adjusted to purify the pump. If necessary, a small amount of gas can be introduced at the pump inlet to expedite the purification process. If other volatile gases or liquids are being drawn in, it is essential to replace the oil promptly and clean the oil tank if needed.

The ultimate pressure is measured using a seat-type compression mercury vacuum gauge. When measured using a calibrated thermocouple vacuum gauge, the reading may be higher. It is advisable to keep a spare, calibrated gauge tube for comparison in case of suspected gauge contamination or distortion.

4. Noise Issues

Various factors can contribute to noise in the pump, such as:

• Pump design and structure.
• Noise from the motor and pump bearings.
• Issues with the smooth movement of rotating parts, such as vanes.
• Excessive oil intake.
• Noise from fans or drive components.
• Excessive intake air volume or gas ballast operation.
• Loose internal components like baffles.
• Improper installation, causing vibrations.

Addressing these noise issues involves checking and rectifying each possible cause to ensure smooth and quiet pump operation.

Contact us 

For more information about Application of Screw Vacuum Pumps in Solvent Recovery, contact Nuoxutech at contact@nuoxutech.com or visit our website www.nuoxutech.com .You can also reach us on WhatsApp at +86 13849062209.Our team is ready to provide you with professional service and support.

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