| 摘要 |
A technique for controlling the pressure in a closed, sealed article, such as a tennis ball or the like. A needle having a sharp, forward, outer end adapted to puncture the article includes a passage in its rear end which terminates in a flow orifice which opens through the side of the needle, between the ends of the needle. Means are provided at the outer end of the needle to carry a resilient sealing plug. The needle may be attached to a syringe or other appropriate means for injecting or withdrawing air from the article. The article is punctured by the plug-carrying needle which is inserted to expose the flow orifice interiorly of the article and to locate the plug within the article. Air is introduced or withdrawn from the article as desired. When the desired pressure level is reached, the needle is withdrawn. The needle and plug are arranged so that as the needle is withdrawn, the wall of the article engages the plug frictionally to hold it in the hole and effect a seal after the needle is completely withdrawn.
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