Syringe Design 1

[Paul029]

I'm trying to find the minimum and maximum allowable length of a .5ml syringe. The requirement states: The length of the barrel and the design of the re-use prevention feature shall be such that the syringe has a recommended maximum usable capacity of at least 5 % more than the nominal capacity and a recommended maximum capacity of 20 % more that the nominal capacity. How would you calculate the minimum and maximum allowable lengths?

 

[MintJulep]

First I would understand the difference between "usable capacity" and "capacity".

Then I would use math.

 

[IRstuff]

I suggest you study this picture:

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[BUGGAR]

I don't see the point!

 

[IRstuff]

Actually, there isn't one, in that picture. It's a blunt needled syringe, so most likely used for dispensing fluids like solder paste, as opposed to subdermal injection of fluids.

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[3DDave]

IRstuff - I disagree. It's exactly the sort of needle I'd probably jab myself with, probably a solder-paste tattoo.

Fun story - a coworker was mentoring some kid's business group; they made sand/soap/water desk toys with wood frames. At some point I asked how they were getting the liquid in and he said they used hypos. I mentioned that fishing supplies sold worm floaters - bottles with needles to inflate worms to keep them from sinking to the bottom. Poor worms. He laughed it off as the hypos worked fine. 6 months later he thanked me for the worm-float idea. Some parents were concerned about handing teenagers hypodermic needles, but worm floaters were OK.

Still, the original post sounds like home work. Mint Julep's answer was priceless.

 

[MikeHalloran]

In addition to Mint's excellent post (Star for Mint), you should know that it's sort of customary in the syringe industry to set up the bore so that the stroke for the calibrated volume is 60 mm. I don't know of a statutory requirement for that; I suspect it has to do with ergonomics, and with market pressure toward standardization for use with syringe pump mechanisms, and related factors.



Mike Halloran
Pembroke Pines, FL, USA

 

[TheTick]

V=πr²h

 

[IRstuff]

I can think of a couple of reasons why the barrel lengths are what they are:
> The length might be dictated by the legibility of the gradation markings
> Your ability to control the dispense percentage amount/rate would be determined by the length of the barrel



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[IRstuff]

Look at:

http://www.amchro.com/PDFs/Spritzen/syringe-dimensions.pdf

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