There is no fixed time standard for the replacement of bearings in centrifugal fans, and the core depends on three factors: operating conditions, bearing type, and maintenance quality. The industry generally refers to a replacement cycle of "20000-40000 hours (about 2-4 years)" (estimated based on 8000-10000 hours of operation per year), but ultimately needs to be judged based on actual conditions rather than simply looking at time.

1、 Key factors affecting the replacement cycle (determining whether to advance/postpone)

1. Working environment: the most core influencing factor

Adverse working conditions (reduced by 50% -70%): high dust (such as in mining and cement industries), humidity/moisture (such as in papermaking and washing), high temperature (medium temperature>80 ℃), corrosive gases (such as in chemical and electroplating industries), can accelerate bearing wear, corrosion, lubrication failure, and may require replacement within 1-2 years.

Clean room temperature conditions (extended to 4-6 years): such as ventilation in office buildings, laboratories, clean workshops, gas cleaning, temperature of 20-40 ℃, low bearing loss, and significantly extended cycle.

2. Bearing type and quality

Ordinary deep groove ball bearings (such as 6200 series): universal type, with a lifespan of more than 20000-30000 hours, suitable for medium and low speeds, light and medium loads.

Self aligning roller bearings (such as the 22200 series): Strong impact resistance and self-aligning ability, suitable for heavy loads and slightly high vibration scenarios, with a lifespan of 30000-40000 hours.

Imported bearings (such as SKF, NSK): superior materials and precision, with a lifespan 30% -50% longer than domestic ordinary bearings, and the replacement cycle can be correspondingly postponed.

3. Maintenance and upkeep quality

Lubrication in place (key): Regularly add suitable lubricating grease (such as lithium based high-temperature grease for high temperature conditions and sealed grease for dust conditions), control the oil level in the bearing chamber at 1/2-2/3, avoid oil shortage, oil quality deterioration or oil pollution, and can extend the service life by 30% -40%; If the oil is not changed for a long time and the oil is added too much/too little, it may cause the bearings to overheat and burn out, and may fail within a few months.

Installation and alignment: When installing, if the bearing fit is too tight/loose, and there is a large deviation in the alignment of the fan and motor coupling, it will increase the radial load on the bearing, accelerate wear, and shorten the cycle by 20% -30%.

4. Operating load and speed

Full load, high-speed operation (such as the fan working at 100% rated speed for a long time with wind pressure close to the upper limit): the shaft bears a large load, generates more heat, and shortens the service life by 10% -20%.

Intermittent operation, low load: low bearing loss, cycle can be extended by 10% -30%.

2、 More reliable "replacement judgment criteria" (more accurate than time)

In practical use, priority should be given to determining whether to replace based on the following signals, rather than sticking to time:

Abnormal temperature: The temperature of the bearing end cover continues to exceed 85 ℃ (for ordinary bearings) or 95 ℃ (for high-temperature bearings), and even after excluding lubrication and ventilation issues, it still cannot be cooled down.

Obvious abnormal noise: When the bearing is running, there is a "rustling sound", "buzzing sound", "metal friction sound", or the noise increases with the increase of speed, and there is no other mechanical interference (such as impeller rubbing against the shell).

Vibration exceeding the standard: The vibration value of the fan (such as horizontal vibration speed>4.5mm/s, or an increase of more than 50% compared to the initial operation), and after excluding problems such as rotor imbalance and loose anchor bolts, the vibration still cannot be relieved (mostly due to increased clearance caused by bearing wear).

Lubrication failure: The lubricating grease turns black, clumps, has metal debris (upon disassembly for inspection), or the bearing seal is damaged, resulting in oil leakage and dust ingress.

Excessive bearing clearance: When manually moving the fan shaft, significant shaking can be felt (radial clearance>0.5mm, adjusted according to the bearing model), or the rotation may be stuck or not smooth.

3、 Suggested operational plan

Conventional scenarios (clean at room temperature, medium low speed, ordinary bearings): Perform "preventive replacement" every 2-4 years or 20000-30000 hours to avoid sudden failures and shutdowns.

Adverse working conditions (dust, high temperature, corrosion): Check the bearing temperature, noise, and lubrication status every 6-12 months, and replace them promptly if any abnormalities are found; If there are no abnormalities, replacement will be mandatory within 1.5-2 years.

Important equipment (such as critical ventilation in production lines and uninterrupted working conditions): Reserve spare bearings in advance, and immediately stop and replace them in case of any abnormal signals to avoid the expansion of the fault.

Maintenance in place: Check the status of the lubricating grease every 3-6 months (1-3 months for dust conditions), replace the lubricating grease every 6-12 months, and clean the impurities in the bearing chamber, which can greatly extend the replacement cycle.