Importance

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Abstract

Hypodermic syringe or medical sampler has a hollow needle (115) that is automatically retractable after use. A one-piece body (101) moulding has a main chamber for a plunger (105) or sampler container or drug cartridge, a forward chamber (111) to house a spring (133) to bias a needle holder (117), and internal latching formations (141) to retain the needle holder (117) with the spring (133) compressed in the forward chamber until automatic retraction when the latching formations (141) are released by end of plunger movement. Direct plunger-to-body sealing involves an over-size plunger head (105 H) forcing head and wall deformation. Both ends of the spring (133) have seals (119, 160) for the forward chamber (111). The needle, its holder, spring and seals can be installed using a sliding guide. Pressure testing can be combined with needle lubrication, and retraction prevention with sterilising tell-tale. The plunger (105) has top and grip formations (105 F) for the needle holder (117), and the needle can be double ended for taking samples or emptying drug cartridges.

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First Claim