Written and maintained by CASRAI Editorial Board
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General product information only, not medical advice. Choosing, fitting or using an airway device is a clinical decision for trained personnel following the manufacturer’s instructions for use and local protocols. This page does not describe how to use the device.
A nasopharyngeal airway (NPA) is sold by French (Fr) size, by inner diameter in millimetres, and by length, and manufacturers do not label these the same way. The same Fr number maps to different millimetre values in different makers’ own records, so the tables below name the maker for every value. Always read the size on the product’s own labelling.
Nasopharyngeal airway size chart: Fr to mm by manufacturer
Values come from manufacturer-submitted records in FDA’s Global Unique Device Identification Database (GUDID), retrieved through openFDA on 2026-10-30, under product code BTQ. They are labelling data as the manufacturer entered it, not a standard.
| French (Fr) | Flexicare (stated inner diameter, mm) | SunMed PVC line (mm in product name) | Covidien (as recorded) |
|---|---|---|---|
| 20 | 4.0 | 5 | – |
| 22 | 4.5 | 5.5 | – |
| 24 | 5.0 | 6 | 6.0 (listed as outer diameter); another record: inner 6.0, outer 8.0 |
| 26 | 5.5 | not in product name | 6.5 (listed as outer diameter); another record: inner 6.5, outer 8.7 |
| 28 | 6.0 in some records, 6.5 in others | 7 | 7.0 (listed as outer diameter); another record: inner 7.0, outer 9.3 |
| 30 | 7.0 | 7.5 | inner 7.5, outer 10.0; another record lists 7.5 as outer diameter |
| 32 | 7.5 | 8 | 8.0 (listed as outer diameter); another record: inner 8.0, outer 10.7 |
| 34 | 8.0 | 8.5 | inner 8.5, outer 11.3; another record lists 8.5 as outer diameter |
| 36 | 8.5 | 9 | – |
| 38 | 9.0 | – | – |
Length by product line (SunMed)
Length is not fixed by Fr size. SunMed’s records give different lengths for the same Fr number in two product lines.
| French (Fr) | PVC line, length (mm) | Sterile single-use line, length (mm) |
|---|---|---|
| 20 | 115 | 114 |
| 22 | 125 | 114 |
| 24 | 135 | 120 |
| 26 | 145 | 121 |
| 28 | 150 | 132 |
| 30 | 160 | 139 |
| 32 | 175 | 146 |
| 34 | 185 | 157 |
| 36 | 190 | 170 |
How to read the chart
Read across a row only within one maker’s column. Within a single maker the numbers are consistent: in most Flexicare records each 2 Fr step adds 0.5 mm of stated inner diameter, and in SunMed’s PVC product names each 2 Fr step adds 0.5 mm of the size shown in the name. Between makers they are not interchangeable, and one maker may offset the whole scale from another by 0.5 mm.
Equivalence notes: Fr, Ch. and mm
- Fr and Ch. Teleflex records give the size as “Ch. 24” with a catheter gauge of 24 French, so Ch. (Charrière) and Fr are the same number on those labels. Those records give no millimetre value.
- Millimetres can mean different things. Flexicare’s product names say “ID Size”, which is inner diameter. Some Covidien records list the same millimetre figure under outer diameter and others list a larger outer diameter next to it.
- Adjustable-flange products exist in Teleflex and SunMed catalogues, and SunMed’s adjustable line uses its own “SZ” numbers with lengths that match the PVC line at the same number.
Common mix-ups
- Treating a size from one chart as valid for every brand. A 34 Fr airway is 8.0 mm inner diameter in Flexicare’s records and 8.5 mm in Covidien’s and in SunMed’s product name.
- Reading an outer-diameter figure as inner diameter, or the reverse. Covidien’s 34 Fr appears with 8.5 mm as inner diameter (outer 11.3 mm) in one record and with 8.5 mm as outer diameter in another.
- Assuming length follows from Fr. SunMed’s 36 Fr is 190 mm in the PVC line and 170 mm in the sterile single-use line.
- Assuming single-use or latex status from the product type. GUDID records carry a separate single-use flag and a natural rubber latex flag, and both vary between records. Check the label.
Regulatory identification
Under 21 CFR 868.5100, a nasopharyngeal airway is a device used to aid breathing, inserted through the nose into the pharynx to provide a patent airway. It is a Class I device, exempt from premarket notification subject to the limits in 21 CFR 868.9. FDA’s product code is BTQ, listed as “Airway, Nasopharyngeal”. The regulation does not define sizes, so sizing is whatever the manufacturer’s labelling states.
How to measure or choose
Selecting a size is a clinical judgement made under the manufacturer’s instructions for use and the user’s own protocols. This page does not give selection criteria. For the sizing logic of related airway devices, see the CASRAI guides on oral airway sizes, laryngeal mask airway sizes and endotracheal tube sizes. Equipment that sits alongside these in emergency stock is covered in what is a crash cart and respiratory therapy equipment.
FAQ
Is there a single nasopharyngeal airway size chart?
No. Each manufacturer states its own Fr, millimetre and length values, and they differ between makers and between product lines of the same maker, as the tables above show. Check your product’s labelling.
What does Fr mean on a nasopharyngeal airway?
Fr is the French size printed on the device. Some labels write it as Ch. The millimetre figure that goes with it depends on the maker and on whether it is quoted as inner or outer diameter.
Is a nasopharyngeal airway regulated?
Yes. FDA classifies it as Class I under 21 CFR 868.5100 (product code BTQ), exempt from premarket notification subject to the limitations in 21 CFR 868.9.
Sources
- FDA, Global Unique Device Identification Database (GUDID) records for product code BTQ, via the openFDA device UDI endpoint: https://api.fda.gov/device/udi.json?search=product_codes.code:BTQ&limit=100. Manufacturer-submitted data from Flexicare Medical Limited, SunMed LLC, Covidien LP and Teleflex Incorporated. Date checked: 2026-10-30.
- FDA, openFDA device classification, product code BTQ: https://api.fda.gov/device/classification.json?search=product_code:BTQ. Date checked: 2026-10-30.
- 21 CFR 868.5100, Nasopharyngeal airway: https://www.law.cornell.edu/cfr/text/21/868.5100. Date checked: 2026-10-30.
