What should always be done before operating pneumatic tools?

Before operating pneumatic tools, it is essential to check for leaks. This is critical for both safety and efficiency. Pneumatic tools rely on compressed air to function, and any leaks in the air lines or connections can lead to reduced tool performance and increased air consumption. Moreover, air leaks can create potential hazards, such as unintended tool activation or loss of control, which can lead to accidents or injuries. By ensuring there are no leaks before using the tools, a mechanic can help prevent hazardous situations and ensure that the tools operate as intended.

Ensuring that the area is clean, disconnecting from the power source, and checking tool inventory, while all important practices, do not directly address the functionality and safety of pneumatic tools in the immediate context of their operation. Cleanliness can help prevent accidents, but it is not specific to pneumatic tools. Disconnecting from the power source applies more to electric tools, and checking tool inventory is more of an organizational task rather than a safety measure before operation. Thus, checking for leaks is the most critical action to undertake before using pneumatic tools.