What does the presence of blisters in the outer rubber layer of a hose indicate?

The presence of blisters in the outer rubber layer of a hose indicates that the inner tube is coming through the reinforcement. This typically occurs when there is a failure in the hose structure, allowing the inner material to separate and push against the outer layer, resulting in visible blisters. This condition often signifies that the integrity of the hose is compromised, which could lead to leaks or rupture if not addressed. Recognizing this issue is crucial for maintaining safety and functionality in systems that rely on the hose.

On the other hand, overheating oil may cause degradation of the hose materials, but it typically does not manifest as blisters in the outer rubber. Likewise, while oil leaking through the reinforcement can lead to other significant problems, it does not necessarily cause blisters. Finally, blisters are not considered a normal occurrence; their presence usually indicates a failure that requires immediate attention to prevent hose failure.