Maintenance Precautions for Dust Removal Equipment in Shot Blasting and Sandblasting Workshops

For large shot blasting and sandblasting workshops, the dust collection effect and dust e

mission safety of the production line's sandblasting room are crucial. This not only ensures compliance with emission standards but also guarantees employee health. However, equipment managers of sandblasting production lines often know very little about the maintenance steps of dust collectors.

Typically, shot blasting and sandblasting workshops are equipped with dust collectors manufactured by professional dust removal companies. In the initial stages of a new production line, the dust collection effect is commendable. 

However, once the dust collector filter cartridges leak dust, especially in emergency situations such as exceeding emission limits, equipment managers are often at a loss, not knowing where to start: Is it time to replace the filter cartridges due to their lifespan, or does the dust collector equipment need repair?

If the dust collector leaks dust for a long time, it will not only lead to serious exceedances of emission standards but may also cause forced shutdowns for troubleshooting and repair. A well-maintained dust collector will not have these problems.

Key Operating Indicators of Dust Collectors

To know whether the dust removal equipment is operating normally, you first need to understand the five key operating indicators of the dust collector:

1. Working Pressure Difference:

Definition: The working pressure difference is an indicator of the degree of blockage or permeability of the filter cartridge. 

Inspection focus: For original filter cartridges, this parameter is generally around 0.2~2.0 in.wg (50~500 Pa) for a long time. The dust collector has low resistance, the fan has a large airflow, but the actual power consumption is very low.

2. Dust Cleaning System Operation

Definition: The dust cleaning system refers to the reverse blowing diaphragm valve/solenoid valve/pressure difference controller/compressed air pressure regulating valve, etc.

Inspection focus:

① Automatic or timed reverse blowing and dust cleaning should be performed in each shift to ensure that the dust collected on the surface of the filter cartridge is blown off in time, preventing excessive/overheated iron powder from damaging the filter cartridge.

② Check whether the diaphragm valve/solenoid valve for reverse blowing and dust cleaning is operating normally. The sound of the diaphragm valve during reverse blowing and dust cleaning requires the personal experience of on-site personnel.

③ A visible inspection item is the pressure gauge for the compressed air used for reverse blowing, which is generally in the normal range of 0.60~0.62 MPa. 3. Dust Collection Efficiency:

Definition: Dust collection efficiency refers to the ability of the suction port to collect dust. Inspection focus: Ensure good dust collection efficiency, especially in semi-open shot blasting production lines. 

It is crucial to ensure that no dust spills into the workshop, and the site environment is clean with no steel grit leakage.

4. Dust Bin Level:

Definition: Dust bin level refers to the height of the collected dust in the bin. Inspection focus: Is there any significant change in the amount of collected dust? When the dust bin is about 70% full, the collected dust needs to be cleaned out promptly. 

The amount of dust collected from the dust collector and production lines should be basically the same under the same production capacity.

5. Fan Frequency or Air Damper:

Definition: The fan frequency or air damper is the device that regulates the total airflow.

Inspection focus: Generally, the airflow distribution at each dust collection hood of the shot blasting machine should not be adjusted arbitrarily, otherwise, it may affect the quality of shot blasting. This is especially true for precision shot blasting production lines with surface finish requirements, such as springs. Therefore, the entire shot blasting and dust collection system requires a relatively constant airflow, and the operating resistance of the filter cartridges should not be too high.

Important Maintenance Measures

To ensure that the dust collector maintains excellent dust collection efficiency and meets emission requirements, Coating World recommends the following annual maintenance measures:

1. Replacement of Dust Collector Filter Cartridges:

① Filter cartridges that have been in use for about 1-1.5 years are recommended to be replaced regularly. 

Continuing to use filter cartridges beyond their service life may lead to filter cartridge damage, dust leakage to the fan discharge port, resulting in complaints and greater losses.

② If the working pressure difference gradually rises from 0.2 and exceeds the warning value for a long time (e.g., 3.0-4.0 in.wg), the time of filter cartridge damage and dust leakage can be predicted based on past experience with specific production lines, 

and the cartridges can be replaced in advance.

The image above shows that the working pressure difference is still within the normal range.

③ Misguided actions can lead to artificial deformation and damage of the filter cartridges. Many users remove the filter cartridges every month and clean them with a manual air gun, which often leads to artificial deformation and damage of the filter cartridges, resulting in significant leakage, and ultimately forcing premature replacement of the filter cartridges. 

2. Repair kits or complete replacement of diaphragm valves and solenoid valves:

Due to the limited lifespan of pneumatic components, it is necessary to regularly replace the entire repair kit to prevent fatigue, aging, and damage to consumables such as rubber, plastic, and springs during annual maintenance.

3. On-site inspection of the electrical control box:

Regular checks of automatic differential pressure setting parameters, back-flushing function, and cleaning and tightening of the control box are necessary to ensure that the dust collector maintains excellent dust collection efficiency and meets emission requirements.

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