What method is used to ventilate a manhole during maintenance?

• A. Forced fresh air into the manhole with a blower
• B. Fire suppression system
• C. Automatic lighting
• D. Welding ventilation

Answer: (A)

Ventilating a manhole during maintenance is about ensuring a safe breathing environment in a confined space. The best method is to force fresh air into the space with a blower. This positive-pressure air supply pushes contaminated air out and dilutes any hazardous gases, helping maintain adequate oxygen levels for workers. It’s a straightforward, effective way to reduce risks from gases like methane, hydrogen sulfide, and carbon monoxide.

The other options don’t provide proper air supply for safety: a fire suppression system isn’t used to ventilate a space; automatic lighting doesn’t improve air quality; welding ventilation is aimed at removing welding fumes and isn’t the general solution for ventilating a manhole during maintenance. Always couple ventilation with gas monitoring and proper confined-space safety procedures.