Which condition could make hydraulic systems more hazardous than pneumatic systems?

Hydraulic systems are often considered more hazardous than pneumatic systems primarily due to the increased fire risk associated with hydraulic fluids. Hydraulic systems operate using liquids, which can be flammable, especially if they leak or are exposed to high temperatures. The presence of these flammable liquids means that there is a greater potential for fire hazards in environments where hydraulic systems are used.

In contrast, pneumatic systems utilize gases, which are generally not flammable under normal operating conditions. This inherent difference in the medium used contributes to the safety profile of each system, where hydraulic systems can present greater dangers due to their fluid dynamics and the properties of the hydraulic fluids involved. Therefore, the heightened risk of fire within hydraulic systems serves as a critical reason for their classification as more hazardous compared to pneumatic systems.