A client in Bangladesh called after their tube axial fan tripped the breaker three times in one week during a hot spell. The ambient temperature in their mining facility was above the motor rated limit. This case led us to document a systematic approach to thermal overload diagnosis.
Problem: Unusual Noise
New or changing noise from a tube axial fan in a mining facility almost always indicates a developing problem. Broadband noise increase suggests blade fouling or erosion. Tonal noise at blade-pass frequency typically indicates system resonance or flow instability. Rattling or knocking sounds point to loose components or foreign objects in the airstream.
If the noise level exceeds the 60 to 80 dB(A) specification, inspect the impeller, check clearances between the impeller and housing, and verify that inlet conditions are uniform. Non-uniform inlet flow is a common cause of tonal noise that does not appear on the factory test curve.
In practice, this means that mining facilities in Bangladesh should establish a clear specification document before approaching vendors. The document should include the design airflow (10,000 to 100,000 m3/h), required static pressure (1,000 to 5,000 Pa), operating temperature range (-10 to 50 C), material preference (galvanized steel (Q235)), noise limits (60 to 80 dB(A)), and any certification requirements (EAC, ISO 9001). Projects that skip this step typically experience 20 to 30 percent more change orders during installation, which drives up costs and delays commissioning.
Problem: High Motor Current
A tube axial fan drawing higher motor current than the commissioning baseline has either increased system resistance or a mechanical problem. The diagnostic process starts with measuring the operating point: if airflow is lower than baseline at higher pressure, the duct system has changed. If airflow is at or above baseline but current is still high, check the impeller for fouling (added weight increases power demand).
In mining applications in Bangladesh, the most common cause of gradually increasing motor current is filter loading. Replacing clogged filters can reduce motor current by 10 to 15 percent and bring the operating point back to design.
The choice of galvanized steel (Q235) for a tube axial fan in a mining application involves balancing initial cost against lifecycle performance. In mildly corrosive environments, galvanized steel with an epoxy coating can extend service life by 5 to 8 years compared to uncoated steel. In severely corrosive environments, stainless steel or FRP construction may be required despite the higher initial cost, because the alternative is premature equipment replacement at 3 to 5 years.
Problem: Intermittent Shutdowns
If a tube axial fan trips off periodically but restarts without any apparent problem, the most likely causes are motor overload (triggered by high current during transient conditions), VFD fault (caused by power quality issues or parameter misconfiguration), or a safety interlock that is being triggered by an unrelated system.
Check the fault log on the VFD and the motor protection relay. In mining facilities in Bangladesh, we frequently find that the motor overload setting was left at the default value rather than being adjusted for the actual operating current. Setting it correctly typically resolves intermittent trip issues.
Keruite's field engineers in Bangladesh have observed that tube axial fan systems in mining applications often operate at conditions different from what was assumed during design. The most common discrepancy is system resistance: actual duct pressure drop frequently exceeds the calculated value by 10 to 25 percent. This is why we recommend including a 10 percent safety margin on static pressure and verifying the operating point during commissioning against the certified performance curve.
| Parameter | Specification |
| Airflow Range | 10,000 to 100,000 m3/h |
| Static Pressure | 1,000 to 5,000 Pa |
| Motor Power | 37 kW (IE2) |
| Material | galvanized steel (Q235) |
| Temperature Range | -10 to 50 C |
| Impeller Balance | G6.3 (ISO 1940) |
| Noise Level | 60 to 80 dB(A) |
| Certifications | EAC, ISO 9001 |
| Standards | EN 12101-3, AMCA 210/300 |
Documenting System Performance
A tube axial fan in a mining application should have a performance record that starts at commissioning and continues throughout its service life. The initial record includes the certified performance curve, commissioning measurements (airflow, pressure, motor current, vibration), and the design point comparison. Subsequent entries record maintenance activities, performance changes, and any modifications.
This record is essential for warranty claims, EAC and ISO 9001 compliance audits, and replacement planning. In Bangladesh, regulatory inspections often request this documentation, and having it organized and current significantly reduces the inspection time.
Environmental and Site Considerations
Site-specific conditions in Bangladesh can significantly affect tube axial fan performance in mining applications. High ambient temperatures (-10 to 50 C) may require motor derating and additional cooling. High humidity or corrosive atmospheres affect material selection (galvanized steel (Q235) with appropriate coatings or upgrades). Dust loading in the airstream determines filter type and replacement intervals.
the company's project engineers in Bangladesh conduct site assessments before finalizing tube axial fan specifications to identify these conditions early. Addressing them during the design phase costs a fraction of what it costs to fix problems after installation.
Conclusion
Every tube axial fan project in mining applications has its own unique requirements, but the engineering fundamentals remain the same. The parameters and practices discussed here have been validated across hundreds of installations. Contact our team for project-specific guidance.