Birmingham gauge explained

The Birmingham gauge[1] is a wire gauge system, and is also used to specify thickness or diameter of hypodermic needles and tube products.

Terminology

Birmingham gauge is also known as the Stubs Iron Wire Gauge or Birmingham Wire Gauge. It is not the same as, though similar to, the Stubs Steel Wire Gauge.

Birmingham gauge is often simply termed Gauge, with the abbreviation G.[2] However, this should not be confused with French gauge.

System

The gauge starts at the lowest gauge number of 5Ø or 00000, corresponding to the largest size of, and runs to the highest gauge number of 36, corresponding to the smallest size of . Size steps between gauges range from between high gauge numbers to between the two lowest gauge numbers and do not correspond to a particular mathematical pattern, although for the most part the steps get smaller with increasing gauge number.[3] Concerning wire and fine tubing, the gauge number is used to specify the outside diameter of the product, whereas for larger mechanical tubing the gauge number specifies the wall thickness independent of the overall size of the tube.

In medicine, the Birmingham gauge specifies the outside diameter of hypodermic needles, catheters, cannulae and suture wires. It was originally developed in early 19th-century England for use in wire manufacture, and began appearing in a medical setting in the early 20th century.

Another common needle gauge system is the French catheter scale.

Needle wire gauge was derived from the Stubs Iron Wire Gauge.

Sizes of hypodermic needles

Hypodermic needles are available in a wide variety of outer diameters described by gauge numbers. Smaller gauge numbers indicate larger outer diameters.[4] Inner diameter depends on both gauge and wall thickness. The following chart shows nominal inner diameter and wall thickness for regular-wall needles.[5] Thin-wall needles (not shown) have identical outer diameters but larger inner diameters for a given gauge.

Gauge,
G
Nominal outer diameterNominal inner diameterNominal wall thicknessISO6009
color[6]
(inch)(mm)(inch)(mm)(inch)(mm)
70.180 ± 0.0014.572 ± 0.0250.150 ± 0.0033.810 ± 0.0760.015 ± 0.0010.381 ± 0.025(undefined)
80.165 ± 0.0014.191 ± 0.0250.135 ± 0.0033.429 ± 0.0760.015 ± 0.0010.381 ± 0.025(undefined)
90.148 ± 0.0013.759 ± 0.0250.118 ± 0.0032.997 ± 0.0760.015 ± 0.0010.381 ± 0.025(undefined)
100.134 ± 0.0013.404 ± 0.0250.106 ± 0.0032.692 ± 0.0760.014 ± 0.0010.356 ± 0.025Olive brown
110.120 ± 0.0013.048 ± 0.0250.094 ± 0.0032.388 ± 0.0760.013 ± 0.0010.330 ± 0.025Green-yellow
120.109 ± 0.0012.769 ± 0.0250.085 ± 0.0032.159 ± 0.0760.012 ± 0.0010.305 ± 0.025Pale blue
130.095 ± 0.0012.413 ± 0.0250.071 ± 0.0031.803 ± 0.0760.012 ± 0.0010.305 ± 0.025Purple
140.083 ± 0.0012.108 ± 0.0250.063 ± 0.0031.600 ± 0.0760.010 ± 0.0010.254 ± 0.025Pale green
150.0720 ± 0.00051.829 ± 0.0130.0540 ± 0.00151.372 ± 0.0380.0090 ± 0.00050.229 ± 0.013Blue-grey
160.0650 ± 0.00051.651 ± 0.0130.0470 ± 0.00151.194 ± 0.0380.0090 ± 0.00050.229 ± 0.013White
170.0580 ± 0.00051.473 ± 0.0130.0420 ± 0.00151.067 ± 0.0380.0080 ± 0.00050.203 ± 0.013Red-violet
180.0500 ± 0.00051.270 ± 0.0130.0330 ± 0.00150.838 ± 0.0380.0085 ± 0.00050.216 ± 0.013Pink
190.0420 ± 0.00051.067 ± 0.0130.0270 ± 0.00150.686 ± 0.0380.0075 ± 0.00050.191 ± 0.013Cream
200.03575 ± 0.000250.9081 ± 0.00640.02375 ± 0.000750.603 ± 0.0190.00600 ± 0.000250.1524 ± 0.0064Yellow
210.03225 ± 0.000250.8192 ± 0.00640.02025 ± 0.000750.514 ± 0.0190.00600 ± 0.000250.1524 ± 0.0064Deep green
220.02825 ± 0.000250.7176 ± 0.00640.01625 ± 0.000750.413 ± 0.0190.00600 ± 0.000250.1524 ± 0.0064Black
22s0.02825 ± 0.000250.7176 ± 0.00640.00600 ± 0.000750.152 ± 0.0190.01110 ± 0.000250.2826 ± 0.0064(undefined)
230.02525 ± 0.000250.6414 ± 0.00640.01325 ± 0.000750.337 ± 0.0190.00600 ± 0.000250.1524 ± 0.0064Deep blue
240.02225 ± 0.000250.5652 ± 0.00640.01225 ± 0.000750.311 ± 0.0190.00500 ± 0.000250.1270 ± 0.0064Medium purple
250.02025 ± 0.000250.5144 ± 0.00640.01025 ± 0.000750.260 ± 0.0190.00500 ± 0.000250.1270 ± 0.0064Orange
260.01825 ± 0.000250.4636 ± 0.00640.01025 ± 0.000750.260 ± 0.0190.00400 ± 0.000250.1016 ± 0.0064Brown
26s0.01865 ± 0.000250.4737 ± 0.00640.00500 ± 0.000750.127 ± 0.0190.00680 ± 0.000250.1734 ± 0.0064(undefined)
270.01625 ± 0.000250.4128 ± 0.00640.00825 ± 0.000750.210 ± 0.0190.00400 ± 0.000250.1016 ± 0.0064Medium grey
280.01425 ± 0.000250.3620 ± 0.00640.00725 ± 0.000750.184 ± 0.0190.00350 ± 0.000250.0889 ± 0.0064Blue-green
290.01325 ± 0.000250.3366 ± 0.00640.00725 ± 0.000750.184 ± 0.0190.00300 ± 0.000250.0762 ± 0.0064Red
300.01225 ± 0.000250.3112 ± 0.00640.00625 ± 0.000750.159 ± 0.0190.00300 ± 0.000250.0762 ± 0.0064Yellow
310.01025 ± 0.000250.2604 ± 0.00640.00525 ± 0.000750.133 ± 0.0190.00250 ± 0.000250.0635 ± 0.0064White
320.00925 ± 0.000250.2350 ± 0.00640.00425 ± 0.000750.108 ± 0.0190.00250 ± 0.000250.0635 ± 0.0064Deep green
330.00825 ± 0.000250.2096 ± 0.00640.00425 ± 0.000750.108 ± 0.0190.00200 ± 0.000250.0508 ± 0.0064Black
340.00725 ± 0.000250.1842 ± 0.00640.00325 ± 0.000750.0826 ± 0.0190.00200 ± 0.000250.0508 ± 0.0064Orange

Rapid blood transfusion through 23G or smaller needles can cause hemolysis (rupturing of red blood cells).[7]

Sizes of catheters

This includes peripheral venous catheters. The gauge compared to outer diameter is the same as for needles, but the color coding is different.

GaugeOuter diameter
(mm)
Maximum flow rate
(ml/min)
Color
14 2.0 250–300 Orange
16 1.7 180 Grey
18 1.3 75–120 Green
20 1.1 40–80 Pink
22 0.9 42-55 Blue
24 0.7 20-35 Yellow
26 0.6 10-13[8] Black

See also

Further reading

External links

Notes and References

  1. https://books.google.com/books?id=Te7TAAAAQBAJ&pg=PA400 Page 400
  2. Web site: 'French', 'gauge' and millimeters. University of California, San Francisco. 2018-02-03. 2017-08-18. https://web.archive.org/web/20170818160042/http://aam.ucsf.edu/article/french-gauge-and-millimeters. dead.
  3. Book: Machinery's Handbook 27. 2004. Industrial Press, Inc. New York, NY. 2520.
  4. Web site: Syringe Needle Gauge Chart . Sigma Aldrich . 20 March 2012.
  5. Web site: Hypodermic Needle Gauge Chart . Medical Tube Technology, Inc. . 20 March 2012 . 10 October 2004 . https://web.archive.org/web/20041010031333/http://www.medtube.com/hypo_chrt.htm . dead .
  6. Web site: ISO 6009:2016 Hypodermic needles for single use -- Colour coding for identification. International Organization for Standardization. Publication date: 2016-08
  7. Miller. Michal A.. Schlueter. Annette J.. Transfusions via hand-held syringes and small-gauge needles as risk factors for hyperkalemia. Transfusion. 44. 3. 2004. 373–381. 0041-1132. 10.1111/j.1537-2995.2004.00653.x. 14996194 . 22956171 .
  8. https://books.google.com/books?id=VYlz7jgD6wgC&pg=PA110 Page 110