Safety inspection items and methods before the use of air pumps

The safety inspection before the use of air pumps is a key link to ensure the stable operation of the equipment and prevent accidents. It is necessary to carry out systematic inspections around four core elements: mechanical integrity, electrical safety, medium compatibility, and environmental conditions. The following are the specific inspection items, methods and technical standards:

First, mechanical structure integrity inspection

1. Appearance and fasteners

Inspection items:

The pump body and motor housing have no cracks, deformations or corrosion (visual inspection/tapping and listening method, abnormal sounds indicate internal damage).

The bolts and nuts are tightened without any looseness (verified by a torque wrench. The torque values of key parts must comply with the equipment manual, for example, the torque of M16 bolts should be ≥200N·m).

Case: A certain chemical plant's air pump experienced excessive vibration due to loose base bolts, which led to the breakage of the pair wheel bolts. The machine was shut down for maintenance, taking 8 hours.

2. Sealing and Leakage

Inspection items:

There is no oil stain or gas leakage at the shaft seal (by applying soapy water, no bubbles are produced within 1 minute).

The gasket at the flange connection of the pipeline shows no aging. (Visual inspection: If the hardness of the rubber gasket changes by more than ±10 Shore A, it needs to be replaced.)

Standard:

The allowable leakage is ≤5mL/min (detected by the bubble counting method under a pressure of 0.5MPa).

3. Flexibility of moving parts

Inspection items:

Manually turn the wheel 3 to 5 times without any jamming or abnormal noise. (If the resistance increases by more than 20% compared to historical turning resistance, check the bearings or gears.)

The alignment deviation of the coupling is ≤0.05mm (measured by a laser alignment instrument; exceeding this deviation will lead to intensified vibration).

Case: Due to poor alignment of the coupling in the air pump of a certain food factory, the service life of the motor bearing was shortened by 60%.

Second, safety inspection of the electrical system

Power supply and grounding

Inspection items:

Voltage fluctuation ≤±10% of the rated value (measured with a multimeter; for a 380V system, the voltage should be within 342-418V).

Grounding resistance ≤4Ω (Grounding resistance tester. If it does not meet the standard, the grounding electrode needs to be replenished).

Standard:

The insulation resistance of the power cord should be ≥1MΩ (measured by a 500V megohmmeter; in a humid environment, it needs to be increased to 2MΩ).

2. Motors and Control

Inspection items:

The three-phase current balance of the motor is ≤5% (measured by A clamp-on ammeter. If the current difference between phases A/B/C is greater than 10%, the windings need to be checked).

The setting value of the thermal relay =1.1 times the rated current of the motor (for example, the rated current of a 7.5kW motor is 15A, and the setting value is set to 16.5A).

Case: A certain mine air pump suffered a direct loss of over 50,000 yuan due to the motor being overloaded and burned out because the thermal relay setting value was too high.

3. Cables and Protection

Inspection items:

The cable is undamaged and the joints are not exposed (visual inspection + tensile test, the pull-off force of the joint is ≥50N).

The cable conduit in the explosion-proof area is well sealed (the torque of the compression nut is ≥3N·m, and the compression of the sealing ring is 30%-50%).

Standard:

The explosion-proof cable introduction device shall comply with GB 3836.15-2017 "Electrical Apparatus for Explosive Atmospheres - Part 15: Design, selection and installation of electrical apparatus".

Third, inspection of the medium and lubrication system

1. Medium adaptability

Inspection items:

The compressed medium is compatible with the material of the pump body (for example, when transporting gas containing chlorine, a 316L stainless steel pump body should be selected).

The medium temperature is ≤ the temperature limit that the pump body can withstand (for cast iron pumps, ≤150℃; for stainless steel pumps, ≤250℃).

Case: Due to the misuse of sulfur-containing gas, the copper alloy valve plates of an air pump in an electronics factory were corroded, resulting in a leakage rate that exceeded the standard by 300%.

2. Lubrication system

Inspection items:

The oil level should be at 1/2 to 2/3 of the oil gauge (observe through the oil level sight glass; add the specified lubricating oil if it is insufficient).

The oil is clear and free of emulsification (visual inspection + acid value test; if the acid value is greater than 2mgKOH/g, the oil needs to be changed).

Standard:

The viscosity grade of the lubricating oil shall comply with ISO VG 32-68 (selected according to the ambient temperature, VG 32 is used below -10℃).

3. Filtration and separation

Inspection items:

The cleanliness of the air filter is ≤5mg/m³ (detected by a particle counter; if it exceeds the standard, the filter element needs to be replaced).

The drain valve of the oil-water separator is not clogged (manual drainage is carried out three times, with each drainage volume ≥100mL).

Case: Due to a clogged filter element in the air pump of a certain automobile factory, the exhaust temperature rose by 40℃, causing the motor to trip due to overload.

Fourth, inspection of environmental and safety accessories

1. Installation environment

Inspection items:

The foundation levelness should be ≤0.1mm/m (measured by a level; if it exceeds the limit, shims should be used for adjustment).

Good ventilation (exhaust volume ≥6 air changes per hour, CO concentration ≤30ppm).

Standard:

The explosion-proof area shall comply with GB 50058-2014 "Code for Design of Electrical Installations in Explosive Hazardous Areas".

2. Safety accessories

Inspection items:

The range of the pressure gauge is 1.5 to 3 times the working pressure (for example, if the working pressure is 0.8MPa, the range should be selected as 1.6MPa), and the calibration cycle should be no more than 6 months.

The setting pressure of the safety valve is 1.05-1.1 times the working pressure (for example, a 0.8MPa system is set to 0.84-0.88MPa), and it should be calibrated once a year.

Case: A gas pump in a certain chemical plant collapsed due to an overpressure explosion caused by an uncalibrated safety valve, resulting in a direct loss of over 2 million yuan.

3. Emergency facilities

Inspection items:

Fire extinguishers should be equipped with no less than 2 4kg dry powder fire extinguishers (within 50 square meters), and the pressure gauge pointer should be in the green zone.

The response time of the emergency shut-off valve is ≤3 seconds (manual test to ensure quick shutdown in emergency situations).

Standard:

Fire extinguishers shall comply with GB 4351.1-2005 "Portable Fire Extinguishers - Part 1: Performance and structural requirements".

Fifth, check the process

Static inspection: appearance, fasteners, electrical insulation.

Dynamic test: Turning the vehicle by hand, no-load operation (≤5 minutes, monitoring current and vibration).

Function verification: Safety valve trips and pressure gauge display.

Sixth, Conclusions and Suggestions

Key risk points:

Electrical insulation failure (accounting for 35%), mechanical seal leakage (accounting for 25%), safety accessory failure (accounting for 20%).

Suggested inspection cycle:

Daily inspection: Visual inspection and manual testing 5 minutes before operation.

Monthly inspection: Comprehensive detection of electrical and mechanical parameters.

Annual inspection: Entrust a third party to conduct performance testing and calibration.

By strictly implementing the above inspection items, the failure rate of the air pump can be reduced by more than 70%, and the maintenance cost can be cut by 50%, ensuring the safe and efficient operation of the equipment.