Enhancing Efficiency and Safety Through Effective Access Systems in Material Handling Chutes
Access systems, such as doors and work platforms, should be installed to facilitate easy reach and observation of equipment. Addressing flow issues within chutes becomes more manageable when the material path can be monitored. Predicting the exact path of material within a chute is challenging, underscoring the necessity for observation to adjust diverters, gates, and grizzly bars. Many transfer chutes typically feature only one inspection door, often near the head pulley. However, this location limits the visibility of the material path in the lower chute and skirted area, where problems frequently arise.
Ideally, chutes should incorporate observation openings with easily operable covers positioned away from the material path. These openings must allow safe monitoring of material flow and component wear at critical installation points. To ensure safety, these openings should be restricted in size or protected with fixed bars or screens to prevent personnel from reaching in or material from escaping. Adequate lighting at access points is crucial; while overhead lighting suffices in some cases, high-power spotlights or strobes may be necessary for observing material movement deep within the chute.
For maintenance and repair purposes, lighting levels of 540 to 1080 lux (50 to 100 foot-candles) are recommended. Given that many bulk materials absorb light and considering the distance to the observed problem, installations may require lighting rated as high as 10 million lux (900,000 foot-candles) to achieve sufficient illumination.
Inspection doors should be side-opening and sized to allow personnel a clear and safe view of internal components. They must be installed on the non-wearing side(s) of the chute to minimize exposure to impacting or abrasive materials. Doors should be designed with corrosion-resistant hinges and latching systems, ensuring they are easy to operate even in tight spaces. It's crucial that all ports maintain a dust-tight seal when closed securely.
Modern access door designs include hinged metal doors with easy-opening latches or flexible rubber "snap-on" doors that provide both dust-tight closure and simple, tool-free operation, suitable for locations with limited clearances.
Door sizes should be sufficient to meet access requirements. For systems like belt cleaners, doors measuring 225 by 300 millimeters (9 by 12 inches) or 300 by 350 millimeters (12 by 14 inches) are generally adequate. For accessing major components such as chute liners or for personnel entry, larger door sizes of 450 by 600 millimeters (18 by 24 inches), 600 by 600 millimeters (24 by 24 inches), or larger are necessary.
Poorly designed doors with difficult-to-operate hinges and latches can hinder access. Inadequate door seals susceptible to abrasion and wear from materials and tools used through the doors can lead to dust issues. Some access doors may also feature small ledges or flat areas where combustible materials like coal can accumulate, posing fire and explosion risks.