Why should you never check a hydraulic line under pressure for a leak with your hand?

Checking a hydraulic line under pressure with your hand poses a significant risk because pressurized fluid can indeed penetrate the skin, causing serious injury. This condition, known as a hydraulic injection injury, occurs when high-pressure fluid enters the body, potentially leading to damage to underlying tissues and requiring immediate medical attention. The fluid can inject into the bloodstream or tissue, causing an array of complications.

Though other reasons might be relevant to safety, the most direct and critical concern is the potential for the fluid to penetrate the skin, highlighting the importance of safety precautions when working with pressurized systems. Understanding this risk reinforces the necessity of using proper tools and methods to safely check for leaks or malfunctions without exposing oneself to dangerous conditions.