Butterfly Needle Gauge Guide: Tubing, Safety and Disposal

Quick summary: a winged infusion set — a butterfly — is a short single-use needle with two plastic wings and a length of flexible tubing ending in a connector. The three specification decisions are gauge (21G to 25G), tubing length and whether the set carries a safety mechanism. This reference covers those choices, the standards behind them, disposal and the records involved; sampling and access technique belong to the clinic's procedures and the device instructions for use.

What is a winged infusion set?

A winged set consists of a short needle on a hub with two flat plastic wings, joined to flexible tubing that ends in a connector. The wings let the device be held at a shallow angle against the skin, and the tubing allows the hub to sit flat while a sample or infusion line is managed a short distance away. The connector is usually a Luer lock or Luer slip, which is what determines whether the set can be attached to a syringe, a vacuum holder or an infusion line.

The needle element falls within the single-use hypodermic needle family, and the peripheral access devices it is often compared with are covered by their own standards. For a buyer, the useful distinction is that a winged set is a short-term device: it is used for a collection or a brief infusion and then disposed of, unlike a peripheral catheter that stays in the vein.

What gauges are available?

Gauge is the outer diameter of the needle and it runs opposite to intuition: 21G is thicker than 25G. Winged sets are supplied commonly at 21G, 23G and 25G, with 3/4 inch as the standard length and 1/2 inch or 1 inch available. Gauge determines how quickly fluid moves through the needle, which is why the choice is driven by the flow the task requires.

Two consequences follow from stocking a single gauge. Where the working gauge is too large for the vein in front of the operator, the device is more likely to be repositioned or replaced; where it is too small for the task, flow becomes the limiting factor. Most clinics therefore hold a working gauge plus one smaller gauge, and treat the third as an exception line.

When is a winged set selected instead of a catheter or a straight needle?

The three device families cover different durations and control needs, and the selection criteria are about the device rather than the patient. A straight needle offers no slack and no independent hold. A winged set adds a low-profile grip and tubing, which suits a single collection or a short infusion where the operator wants the hub flat against the skin. A peripheral catheter is the option when access has to remain in place after the initial procedure.

• Collections from small, fragile or mobile veins, where the lower profile of the wings gives better control of the needle tip.
• Hand veins, which sit at a shallow angle that suits a winged device.
• Short-term fluid administration where leaving a catheter in place is not justified.
• Situations where the tubing keeps the sample point clear of the operator's hands.

The tubing is a specification item rather than packaging. A longer set gives slack, which helps with a moving patient but adds dead volume between the vein and the collection point — a consideration when the sample is small or the analysis is sensitive to dilution. Short sets keep the sample closer to the vein.

Are safety-engineered winged sets required in Ontario?

The sharp on a winged set is exposed from the moment of withdrawal until the device reaches a container, and that window is where needlestick injuries happen. Safety sets add a mechanism — a retracting needle, a sliding shield or a hinged cover — that closes over the sharp as part of the withdrawal motion. ISO 23908 sets out requirements and test methods for sharps protection features on single-use needles and blood sampling devices, and the practical test for a clinic is whether the mechanism can be activated one-handed while the other hand is managing the patient.

In Ontario, O. Reg. 474/07 under the Occupational Health and Safety Act requires health care employers to provide safety-engineered needles where a worker uses a needle to withdraw body fluid or to administer a substance, subject to the exemptions written into the regulation. A clinic that has standardised on conventional winged sets should be able to show the documented reason. Federally regulated workplaces follow the equivalent expectation in the Canada Occupational Health and Safety Regulations.

How are used winged sets disposed of?

Needle end first into a puncture-resistant sharps container at the point of use, with the tubing following. The device is not cut free at the bedside, because that leaves an exposed needle behind and puts a hand in the sharp's path. Containers are closed and replaced before the fill line, and container performance in Canada is described in CSA Z316.6 — drop, puncture and closure requirements rather than capacity alone.

Two adjacent supply points come up in infection prevention audits. Skin preparation products are drawn from single-patient containers and the site is allowed to dry before the device is introduced, because an alcohol layer that has not evaporated reduces the effect of the antisepsis. And specimen labelling happens with the patient identifiers and collection time, because that is the step where mislabelled samples originate — a traceability requirement described in Canadian specimen transport guidance rather than a lab preference.

What should a purchase order specify?

Winged sets are bought in small volumes but read at inspection like any other device. The fields below are the ones a receiving check can verify.

Clinics that also run in-house sterilization can request a rapid reader seed trial to compare spore-test readout workflow, and can review collection and transport hardware in the laboratory consumables range. A three-wall specimen transport bag keeps the requisition with the sample, and graduated leak-proof specimen cups cover the non-blood half of a routine collection round.

References

1. ISO 10555-5:2013 — Intravascular catheters — Sterile and single-use catheters — Part 5: Over-needle peripheral catheters
2. ISO 23908:2011 — Sharps injury protection — Requirements and test methods
3. ISO 23908:2024 — Sharps injury protection — Sharps protection mechanisms for single-use needles
4. ISO 7886-1:2017 — Sterile hypodermic syringes for single use — Part 1: Syringes for manual use
5. O. Reg. 474/07 (Needle Safety) under the Ontario Occupational Health and Safety Act
6. Canada Occupational Health and Safety Regulations, SOR-86-304
7. Medical Devices Regulations, SOR-98-282
8. CCOHS — Needlestick and sharps injuries (OSH Answers)
9. CLSI GP42 — Collection of capillary blood specimens (7th edition)
10. PHAC — Routine practices and additional precautions for preventing the transmission of infection in health care
11. Health Canada — Guidance on medical device establishment licensing (GUI-0016)
12. Comparison of capillary and venous blood sampling for routine coagulation assays (Clinical Biochemistry, 2022)
13. AARC clinical practice guideline: capillary blood gas sampling for neonatal and paediatric patients (Respiratory Care, 2022)
14. Prevalence of needlestick injury among healthcare workers: systematic review and meta-analysis (Environmental Health and Preventive Medicine, 2019)
15. Needlestick injuries: the role of safety-engineered devices in prevention (British Journal of Nursing, 2020)
16. Clinical, economic and humanistic burden of needlestick injuries in healthcare workers (Medical Devices, 2017)
17. Needlestick (StatPearls review, National Library of Medicine)

Related Reading

• Clinical supply and infection prevention learning hub
• Syringe and needle selection: gauge, length and safety features
• Insulin syringe sizing: U-100 barrels, gauge and sharp safety
• Lancet gauge, depth and site: capillary sampling reference
• Pen needle length and gauge: device and specification guide
• Specimen cups vs bags: choosing lab transport containers
• Diagnostic laboratory supply checklist with purchasing links
• clinic consumables

Frequently Asked Questions

What gauge butterfly needle is used most in clinics?

23G is the usual working gauge for routine collections. 21G is held for faster flow and larger volumes, and 25G for small or fragile veins where control matters more than speed. Most clinics stock a working gauge plus one smaller gauge.

Is a butterfly needle the same as a peripheral catheter?

No. A winged infusion set is a short single-use needle with tubing, used for a single collection or a short infusion and then disposed of. A peripheral catheter is a plastic cannula that remains in the vein. Different device families, different parts of the ISO device standards, and different intended durations.

Why use a winged set instead of a straight needle?

The wings give a low-profile grip and let the hub lie flat against the skin, which improves control of the needle tip. The tubing also keeps the collection point a short distance from the operator's hands, which helps with small, fragile or mobile veins.

Does tubing length matter for small-volume draws?

Yes. A longer set adds dead volume between the vein and the collection point, which matters when the sample is small or the analysis is sensitive to dilution. Short sets keep the sample closer to the vein, and the length should be stated in the specification rather than left to whatever arrives.

Are safety-engineered winged sets required in Ontario?

O. Reg. 474/07 under the Occupational Health and Safety Act requires health care employers in Ontario to provide safety-engineered needles where a worker uses a needle to withdraw body fluid or administer a substance, subject to defined exemptions. Where conventional sets are used, the documented reason is what an inspector will ask for.

How should a used butterfly set be disposed of?

Needle end first into a puncture-resistant sharps container at the point of use, with the tubing following. Sets are never cut free at the bedside, and containers are closed and replaced before the fill line, in line with the performance requirements of CSA Z316.6.

What standards apply to winged infusion sets?

The needle element falls within the single-use hypodermic needle family, safety features are described in ISO 23908, and the peripheral access devices these sets are compared with are covered by ISO 10555-5. A specification sheet should name the standard it is describing rather than listing only dimensions.

What should a purchase order for winged sets include?

Gauge and length, tubing length, connector type (Luer lock or Luer slip), whether the set is safety-engineered and what the mechanism is, the standards the needle and safety features are described against, units per box and boxes per case, and expiry visibility for cart stock.

Last updated: September 2026. CliniEco Medical holds MDEL #35334 issued by Health Canada, and supplies clinics, long-term care homes and home-care programs across Canada.