Inspection process and standards for lubrication system

1. Inspection of compressor lubrication system

oil level check

Method: Observe the oil sight glass while the machine is stopped, and the oil level should be at 1/2~2/3 of the scale line (the oil level may decrease during operation and needs to be checked after 30 minutes of shutdown).

Exception handling: When the oil level is below 1/3, it needs to be refilled. If it drops again within a short period of time after refilling, there may be oil leakage or refrigerant dilution oil problems (requiring professional investigation).

Oil quality inspection

Visual inspection: Normal oil should be transparent or light yellow. If there is turbidity, emulsification (white flocculent) or blackening (carbonization), the oil should be changed immediately.

Professional testing: Oil analysis (testing acid value, viscosity, metal particles) should be conducted once a year. Oil should be changed if the following thresholds are exceeded:

Acid value>2.0 mgKOH/g (indicating oil oxidation and deterioration);

The viscosity change exceeds ± 15% (reference value);

Metal particle concentration>50 ppm (indicating component wear).

Oil temperature monitoring

Normal operating oil temperature: piston compressor ≤ 80 ℃, screw compressor ≤ 90 ℃.

Possible causes of high temperature: blockage of oil cooler, insufficient lubrication, excessive load on compressor. It is necessary to clean the heat dissipation components or check the oil circuit.

2. Inspection of vacuum pump lubrication system

Oil pollution assessment

Observe the color of the pump oil: If the sample solvent (such as ethanol, acetone) or water is inhaled, the oil will become cloudy or layered, and should be replaced in a timely manner.

Odor detection: If the oil has a pungent solvent odor, it indicates that it has been contaminated and may corrode the pump body or reduce the vacuum degree.

Maintenance of oil mist filter

Rotary vane pumps are usually equipped with oil mist filters. When obvious oil mist appears at the exhaust port, the filter needs to be replaced (usually every 1000 hours or 6 months).

Long term non replacement may lead to increased consumption of vacuum pump oil, environmental pollution, and decreased lubrication effect.

Prevent oil return

Ensure that the pressure inside the pump is balanced with the atmosphere during shutdown (using an anti backflow valve) to prevent pump oil from flowing back into the vacuum chamber and contaminating the sample.

3. Lubrication of bearings and transmission components

Lubricating grease replenishment cycle

Gearbox, chain drive and other components: Add lithium based grease every 500 hours of operation or 3 months.

Rolling bearings: Apply grease after the first 1000 hours of operation, and then every 2000 hours thereafter (refer to the equipment manual for details).

Abnormal signal

If the temperature of the bearing area rises (>70 ℃) or abnormal noise occurs (such as whistling or jamming), it may be due to a lack of grease or aging of the grease. It is necessary to immediately stop the machine for inspection, clean the old grease, and reapply new grease.

3、 Key points for maintenance and operation of lubrication system

1. Oil change operation specifications

Compressor oil change steps:

Stop the equipment and turn off the power, wait for the oil temperature to drop to room temperature (to avoid burns);

Open the oil drain valve and drain the old oil (if the oil contains refrigerant, it needs to be collected and professionally treated, and cannot be directly discharged);

Rinse the oil circuit with a small amount of new oil (discharge after running the compressor for 5-10 minutes) to remove residual impurities;

Add new oil of the specified model and quantity, and check the oil level again after running for 5 minutes.

Precautions for changing oil in vacuum pump:

Hot oil change (pump stops after running for 30 minutes): When the oil temperature is high, the oil has good fluidity and can carry out more impurities;

Different brands/models of pump oil cannot be mixed (which may cause chemical reactions and result in oil failure).

2. Selection and storage of lubricants

Model matching: Strictly select lubricating oil according to the equipment manual requirements (such as compressors usually labeled with applicable oil brands and viscosity grades, such as ISO VG32, VG46).

Storage requirements: Lubricants should be sealed and stored in a cool and dry place, avoiding direct sunlight and moisture intrusion. It is recommended to use them up within 6 months after opening.

3. Special scenario maintenance

High humidity environment: Vacuum pumps are prone to inhaling moisture, causing oil emulsification. It is recommended to open the pump's drain valve weekly to discharge condensed water, or use vacuum pump oil with strong anti emulsification properties (such as synthetic oil).

Corrosive gas environment: If the freeze-dried sample releases acidic gases (such as salt and acid mist), the oil change cycle should be shortened (once every 1-2 months), and the corrosion inside the pump body should be checked.