What is draft in relation to boiler operations?

In boiler operations, draft refers specifically to the pressure difference that is created to move combustion gases through the boiler and into the chimney or flue. This pressure difference is essential for ensuring that the combustion products are properly vented out of the system. A well-maintained draft is crucial for efficient combustion and helps achieve optimal boiler performance.

When the draft is sufficient, it allows for the effective removal of combustion gases and contributes to maintaining the correct operating conditions within the boiler. If the draft is too weak, it can lead to poor combustion, increased pollution, and potential safety hazards due to the accumulation of harmful gases. Conversely, too strong of a draft can create imbalances, affecting efficiency and operation.

The other options mentioned do not accurately represent the concept of draft in boiler operations. For example, the temperature difference does not define the movement of gases, the velocity of steam pertains more directly to steam flow rather than gas venting, and while fuel consumption is important for boiler efficiency, it does not relate to the gas movement process known as draft.