What is the recommended method for removing ice from sight glasses?

Using alcohol spray is effective for removing ice from sight glasses because alcohol has a lower freezing point than water, which allows it to melt the ice without the risk of refreezing. When applied, the alcohol disrupts the icy layer, helping to clear the sight glass for better visibility.

This method is typically preferred over others due to its efficiency and safety. Hot water, while it may seem like a reasonable option, can introduce thermal shock to the glass, potentially causing it to crack or break. Compressed air could blow snow or ice further into the system instead of removing it effectively, and dry ice poses risks of temperature extremes that can be harmful to the sight glass and surroundings. Therefore, alcohol spray provides a balance of safety and efficiency, making it the best choice for this task.