Conveyors, Material Handling, and Process Equipment

Conveyors, Material Handling, and Process Equipment

Chapter Introduction

This chapter covers the installation, alignment, troubleshooting, and maintenance of conveyor systems and process equipment. For the Red Seal exam, you must master mechanical principles, power calculations, applicable safety standards, and alignment procedures. This chapter is structured to reflect competency blocks G (Conveyors and Process Equipment) and H (Material Transfer Systems) of the qualification profile.

1. Conveyor Classification

1.1 Belt Conveyors

The belt conveyor is the most common type in the mining, forestry, and food processing industries. It consists of an endless belt mounted on drive and return pulleys, supported by carrying idlers.

Critical Components:

Belt Speed Calculation:

v = π × D × N / 60

Where:

Example: A 500 mm pulley rotating at 120 rpm gives:

v = π × 0.5 × 120 / 60 = 3.14 m/s

Belt Tension: The effective tension (Te) is the sum of:

Power Formula:

P = Te × v / η

Where:

1.2 Chain Conveyors

Chain conveyors are used for heavy loads, high temperatures, or abrasive products. Main types:

Bucket Elevator Capacity Calculation:

Q = V × ρ × φ × (3600 / p)

Where:

1.3 Screw Conveyors (Archimedes' Screw)

The screw conveyor moves bulk materials through the rotation of a helix inside a trough. The theoretical capacity is:

Q = 60 × π × (D² - d²) / 4 × p × N × φ × ρ

Where:

Rule of thumb: The maximum speed of a 300 mm screw is approximately 90 rpm for an abrasive product, 165 rpm for a non-abrasive product.

1.4 Vibrating Conveyors

Vibrating conveyors use directional vibrations to move the product through micro-jumps. Typical frequency is 900 to 3600 cycles/min with an amplitude of 1.5 to 10 mm. The attack angle is generally 20° to 30° from the horizontal.

2. Conveyor Components and Accessories

2.1 Idlers and Bearings

Carrying idlers are classified by diameter (89 mm to 219 mm) and load capacity. The selection depends on belt width and load.

Selection Criteria:

2.2 Take-up Devices

The take-up maintains the minimum tension required to prevent belt slip on the drive pulley.

Rule: Take-up travel must be at least 2% of conveyor length for fabric-carcass belts, 1% for steel-cable belts.

2.3 Belt Cleaners

Primary scrapers (at the head) and secondary scrapers (under the pulley) remove adhering product. Poor cleaning causes:

2.4 Guards and Safety Devices

According to the Canadian Electrical Code, Part I (CE Code) and CSA standards, every conveyor must be equipped with:

3. Conveyor Alignment

3.1 Pulley Alignment

Correct pulley alignment is essential to prevent belt mistracking. The laser or straightedge method:

String method: Stretch a string along the top run of the belt. The distance between the string and the pulley must be equal on both sides.

3.2 Gearbox Shaft Alignment

Gearbox alignment onto the drive pulley follows the same principles as coupling alignment (Chapter 5). Typical tolerances:

4. Process Equipment

4.1 Speed Reducers (Gearboxes)

Speed reducers are assemblies of gears or pulleys that reduce speed and increase torque. Types:

Reduction Ratio Calculation:

i = N₁ / N₂ = Z₂ / Z₁

Where:

Total Efficiency of a Multi-stage Reducer:

η_total = η₁ × η₂ × η₃ ...

4.2 Couplings

Couplings transmit torque between the motor shaft and the gearbox or pulley shaft. Common types:

4.3 Brakes and Torque Limiters

Brakes are required on inclined conveyors to prevent load reversal when stopped. Types:

Torque limiters (friction or ball-detent type) protect equipment against overloads. The trip torque is set at 110-130% of rated torque.

5. Power and Capacity Calculations

5.1 Belt Conveyor Power

The total power required is:

P_total = (P_empty + P_load + P_incline + P_accessories) / η

Where:

Simplified Formula (rule of thumb):

P (kW) = (Q × L × μ) / 367 + (Q × H) / 367

Where:

5.2 Belt Conveyor Capacity

The maximum volumetric capacity is:

Q_v = A × v × 3600

Where:

Area A depends on the idler trough angle and the product surcharge angle. For a 35° trough angle and a 20° surcharge angle:

A ≈ 0.11 × B² (where B is in meters, belt width)

5.3 Bucket Elevator Power

P = (Q × H) / (367 × η) + P_drive

Where:

6. Applicable Standards and Codes

6.1 Canadian Electrical Code, Part I (CE Code)

Rule 8-200 of the Canadian Electrical Code, Part I, requires that machinery be equipped with a visible, lockable disconnect switch. Rules 8-202 to 8-210 cover overcurrent and ground fault protection requirements.

6.2 CSA B149.1 (Natural Gas and Propane Installation Code)

For process equipment using gas, CSA B149.1 specifies installation requirements for burners, piping, and safety devices. Rule 5.4 requires an accessible shut-off device within 3 m of the equipment.

6.3 CSA Z432 (Safeguarding of Machinery)

CSA Z432 defines machinery safeguarding requirements, including conveyors. It specifies safety distances for fixed guards and light curtains.

6.4 Other Relevant Standards

7. Troubleshooting and Preventive Maintenance

7.1 Common Belt Conveyor Problems

7.2 Common Gearbox Problems

7.3 Preventive Maintenance Plan

An effective maintenance plan includes:

8. Safety and Lockout Procedures

8.1 Lockout/Tagout (LOTO) Procedure

Before any work on a conveyor or process equipment:

8.2 Conveyor-Specific Hazards

9. Exam Tips

9.1 Typical Questions

Exam questions often cover:

9.2 Answer Strategies

Pitfalls to Avoid

Summary

This chapter covers the essentials for the Red Seal exam on conveyors and process equipment. Master the formulas, standards, and safety procedures — these are the three pillars of exam questions in this domain.