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How many times can I pierce a stopper with a 29G needle before coring?

Asked 6 Oct 2025Modified 10 months agoViewed 12k times
16

I keep a written log of every draw with date, volume and syringe type.

I have read the obvious sources and they disagree with each other, so I would rather ask people who have actually done this.

I have a working setup and a notebook, and I am prepared to be told that my setup is inadequate if that is the answer.

Concretely, what should I do, and how would I know afterwards whether I did it right?

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askedlyoph_cake78k2676 Oct 2025
6Is this U-100 or U-40? It changes the arithmetic by a factor of two and a half. – sian_llewellyn 3 months ago
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