SYRINGE WITH TWO-STAGE SEALING PRESSURE

摘要

A syringe includes a barrel, a plunger, and a sealing member creating a seal between the plunger and the barrel. The barrel includes a first portion with a first inner diameter and a second portion with a second inner diameter that is larger than the first inner diameter. The sealing member engages the first portion of the barrel to give rise to a first contact pressure when the barrel is filled with product. The first contact pressure is sufficient to maintain a gas-tight seal over the expected temperature ranges −25° C. to 40° C. A first force is applied to the plunger to overcome the first contact pressure and move the plunger out of the first portion and into the second portion to dispense product. The sealing member engages the second portion of the barrel to give rise to a second contact pressure that is lower than the first contact pressure. A second force lower than the first force is sufficient to overcome the second contact pressure and move the plunger in the second portion to continue dispensing product. The syringe may include a restraining element for accommodating expansion of the product during freezing.

主权项

1. A syringe for use in a drug infusion system, the syringe comprising:
a barrel having a cylindrical wall, the cylindrical wall having a first portion with a first inner diameter and a second portion with a second inner diameter that is larger than the first inner diameter; a plunger within the barrel; wherein a sealing member of the plunger engages the first portion of the barrel with a first contact pressure when the barrel is filled with product, such that a first force is required to move the plunger with respect to the barrel; wherein a portion of the plunger engages the second portion of the barrel with a second contact pressure that is lower than the first contact pressure, such that a second force is required to move the plunger in the second portion; and wherein the second force is lower than the first force.