If you keep the air inside from escaping by holding the nozzle closed, then the air will get concentrated to higher pressure as you push in the plunger - until the pressure inside the syringe is the same as the pressure you're putting on it with the plunger, at which point you can't push it in anymore, because the air pressure becomes stronger than your finger. The insert further comprises a moderately pliable circumference groove about the insert that matches the syringe thumb ring receivable therein by snapping the insert into place in the thumb ring passage with groove rims being resiliently distorted in allowing the thumb ring to pass into the groove. Proper aspiration requires only 1 or 2 mm of plunger movement so the thumb is only required to pull out against the thumb ring a small distance for aspiration before pushing the plunger at least partially through the syringe cavity. In practice, with medicament in the syringe the plunger is mostly withdrawn from the syringe so the thumb is largely extended. It is a further object that the insert be adapted for facile insertion and removal from the thumb ring. It is further object to provide thumb ring inserts with respective selectively-sized thumb apertures more precisely fitting a plurality of users with different sized thumbs. However, by pushing the plunger in, we are trying to reduce the volume V of the container.
Study sets matching "syringe"
The prior art has not recognized a retraction mechanism with separable parts that relies entirely on clamping force or friction at a smooth walled reduced diameter transition zone in the barrel with mating lands which are slidably or separably released in response to relatively low thumb pressure while having resistance to premature retraction and high blowout pressure resulting from high pressure produced in the fluid chamber during an injection. Referring now to FIGS. The vane 86 may have an elongate flat configuration. In the description that follows, like parts will be referred to by the same reference numerals. Prime among the usual deficiencies of the prior art are problems of complexity, reliability, cost and ease of use. Alternately, ramp can be the smaller diameter step which avoids reentrant angles whereby resistance to removal of the molding core could occur. The plunger 18 may comprise the thumb platform 22 , rigid shaft 30 and a piston 32 which may be rigidly fixed to each other.
USA - Syringe plunger assembly and barrel - Google Patents
The needle holder and spring are installable from the rear of the barrel without the needle. Hooks are often used to releaseably secure retraction mechanisms. A thumb ring insert that reduces the effective size of a syringe thumb ring thumb passage. It is immaterial whether cap 48 moves into the opening at the instant of retraction or after retraction has already occurred because the movement is automatic due to the continued thumb force applied to trigger the retraction. Head has a tip portion forming an opening for a dislodgable stopper having a front portion extending beyond tip
US8152762B2 - Plunger activated vacuum release mechanism for a syringe - Google Patents
Description: Any convenient number may be chosen as the channels are easily molded into the end cap when it is formed. The insert comprises a thumb aperture adapted to receive a user's thumb in a comfortable fit only slightly larger than the user's thumb with the aperture eccentric from the thumb ring passage, located close to a thumb ring bottom where a syringe plunger end connects. First the stopper is moved back and then the needle holder is released. Blowout pressure is still a factor to be considered in connection with stopper