Syringe dead space: difference between revisions
Diff·revision 36 → 37·15:55, 11 Jan 2026
Difference between revision 36 and revision 37 of Syringe dead space. 9 lines changed; the page grew by 1,786 bytes.
| Revision 36 — 10:59, 7 Jan 2026 StabilityStig (talk) move unsourced paragraph to talk 15,887 bytes ±0 | Revision 37 — 15:55, 11 Jan 2026 BUD_Bertram (talk) add DOI 17,673 bytes +1,786 | ||
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| 122 | Design approaches fall into three groups: | 122 | Design approaches fall into three groups: |
| 123 | 123 | ||
| + | 124 | * '''Permanently attached needle.''' The cannula is moulded into the barrel and the plunger tip advances to its proximal end. This achieves the lowest values, of the order of 2–6 µL, and is the standard construction for insulin syringes. | |
| + | 125 | * '''Hub insert.''' A moulded plastic plug fills most of a standard Luer hub, leaving a channel for liquid, so that a conventional detachable-needle syringe achieves roughly 10 µL. The needle remains detachable, which preserves the operational flexibility of a Luer fitting. | |
| + | 126 | * '''Extended plunger tip.''' The plunger tip carries a projection that enters the hub. Values are intermediate and depend on the fit achieved. | |
| + | 127 | ||
| + | 128 | == Measurement and standards == | |
| + | 129 | Dead space is not itself a specified parameter in the principal device standards. ISO 7886-1 specifies the graduated capacity, the tolerance on delivered volume, dimensional requirements, freedom from leakage and the force required to operate the plunger; ISO 8537 does the equivalent for insulin syringes; ISO 7864 covers needles and ISO 9626 the stainless-steel tubing from which they are made. None sets a maximum retained volume, and none requires it to be declared.{{r|iso7886,iso8537,iso7864,iso9626}} | |
| + | 130 | ||
| + | 131 | The practical consequence is that dead space must be measured or inferred rather than looked up. Published measurement follows a gravimetric protocol: the device is assembled, filled with water of known temperature, fully discharged against no back-pressure, and weighed before and after; the retained mass converted to volume gives the dead space. Reported precision is adequate to distinguish the device classes in the table above but not to distinguish nominally identical products from different manufacturers, where differences of 10–20 µL have been reported.{{r|zule2009}} | |
| + | 132 | ||
| 124 | == References == | 133 | == References == |
| 125 | {{reflist}} | 134 | {{reflist}} |