| 摘要 |
PROBLEM TO BE SOLVED: To provide a protective cap (11) to be fitted and installed onto a connecting cylinder portion such as a plug cylinder or hose end portion of a gas cock in an airtight state, which can secure air-tightness over a long period of time, can be easily attached to and detached from the connecting cylinder portion, and is never damaged even when the attachment and detachment are repeated.SOLUTION: The protective cap is composed of a synthetic rubber cylinder opened to one side, and includes a seal portion (10) formed on the inner circumferential surface of the cylinder, the seal portion having an inner diameter smaller than the outer diameter of the body portion of the plug cylinder or hose end portion. A rough surface (1) having a predetermined surface roughness is formed in part or all of the seal portion (10), and a film (2) mainly composed of a solid lubricant is formed on the rough surface (1). |
