What is the primary function of the door block in a conveyor system?

The primary function of the door block in a conveyor system is to prevent door closure when necessary. This component serves an important safety and operational role by ensuring that doors remain open during specific conditions, such as when maintenance is being performed or when the system is not operating correctly. By preventing closure, it helps avert accidents and ensures that personnel can safely access areas of the conveyor system.

The other options may relate to various aspects of conveyor systems, but they do not accurately reflect the main purpose of a door block. Sealing the conveyor, regulating weight distribution, and initiating an alarm system involve different mechanisms and components within the overall system design and functionality, and do not pertain directly to the specific role of the door block.