Devices · Syringes & needles · continued

[2026 update] 0.3 mL versus 0.5 mL versus 1 mL barrels: resolution matters posts 121–125

Devices › Syringes & needles dead volume needle gauge & length subcutaneous injection Solved

This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1 · go to the accepted answer.

j.nwosuTL215 May 2026#121

n.petrov, post #20: Post #18 is right about the mechanism and I think understates the practical bit. Agreed on 0.3 ml versus 0.5 ml, with one qualification that I think matters. The reasoning holds for the case as described. Change the starting assumption and it does not, and the starting assumption is the part nobody states. Go to post

Worth stating the null on 0.3 ml versus 0.5 ml before we explain it: the observation may be nothing. That possibility deserves a sentence and usually does not get one.

11 likes in reply to #20 2mo

b.petrovTL215 May 2026#122

Post #121 is the version of this I will quote in future. One addition.

A note on how 0.3 ml versus 0.5 ml gets discussed rather than on 0.3 ml versus 0.5 ml itself: the confident posts get the replies and the careful ones get ignored, and the careful ones have been right more often.

3 likes 2mo

e.piresTL215 May 2026#123

U-100 means the barrel is graduated for a solution containing one hundred units of insulin per millilitre. For anything that is not insulin, the units are simply hundredths of a millilitre.

0 likes 2mo

a.kowalskiTL216 May 2026#124

Sharps containers are a legal requirement for disposal in several jurisdictions and a sensible precaution everywhere. A rigid sealed container is the minimum.

Old habit: I write down the expected answer before I calculate it.

32 likes 2mo

m.yilmazTL216 May 2026 · edited#125

Agreed, and I will stop repeating the version of this I had been repeating.

16 likes 2mo

This topic was referenced in

A ten-fold dose error caught before injectionDevices › Syringes & needles · 103 replies
Reading U-100 graduations, with a conversion table — what changed sinceDevices › Syringes & needles · 2 replies

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