The

Birmingham Birmingham ( ) is a City status in the United Kingdom, city and metropolitan borough in the metropolitan county of West Midlands (county), West Midlands in England. It is the second-largest city in the United Kingdom with a population of 1. ...

gauge is a

wire gauge Wire gauge is a measurement of wire diameter. This determines the amount of electric current the wire can safely carry, as well as its electrical resistance and weight. Types of wire gauge Wire gauges may be broadly divided into two groups, t ...

system, and is also used to specify thickness or diameter of

hypodermic needle A hypodermic needle (from Greek ὑπο- (''hypo-'' = under), and δέρμα (''derma'' = skin)), one of a category of medical tools which enter the skin, called sharps, is a very thin, hollow tube with one sharp tip. It is commonly used w ...

s 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. 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. 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 Medicine is the science and practice of caring for a patient, managing the diagnosis, prognosis, prevention, treatment, palliation of their injury or disease, and promoting their health. Medicine encompasses a variety of health care pr ...

, the Birmingham gauge specifies the outside

diameter In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle. It can also be defined as the longest chord of the circle. Both definitions are also valid fo ...

catheter In medicine, a catheter (/ˈkæθətər/) is a thin tubing (material), tube made from medical grade materials serving a broad range of functions. Catheters are medical devices that can be inserted in the body to treat diseases or perform a surgi ...

s, cannulae and suture wires. It was originally developed in early 19th-century England for use in

wire Overhead power cabling. The conductor consists of seven strands of steel (centre, high tensile strength), surrounded by four outer layers of aluminium (high conductivity). Sample diameter 40 mm A wire is a flexible strand of metal. Wire is c ...

manufacture, and began appearing in a medical setting in the early 20th century. Another common needle gauge system is the

French catheter scale The French scale, French gauge or Charrière system is commonly used to measure the size of a catheter. It is most often abbreviated as Fr, but can often be seen abbreviated as Fg, FR or F. It may also be abbreviated as CH or Ch (for Charrière, i ...

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

Sizes of hypodermic needles

Hypodermic needle A hypodermic needle (from Greek ὑπο- (''hypo-'' = under), and δέρμα (''derma'' = skin)), one of a category of medical tools which enter the skin, called sharps, is a very thin, hollow tube with one sharp tip. It is commonly used w ...

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

Rapid

blood transfusion Blood transfusion is the process of transferring blood products into a person's circulation intravenously. Transfusions are used for various medical conditions to replace lost components of the blood. Early transfusions used whole blood, but mo ...

through 23G or smaller needles can cause

hemolysis Hemolysis or haemolysis (), also known by several other names, is the rupturing ( lysis) of red blood cells (erythrocytes) and the release of their contents (cytoplasm) into surrounding fluid (e.g. blood plasma). Hemolysis may occur in vivo ...

(rupturing of red blood cells).

Sizes of catheters

This includes

peripheral venous catheter In medicine, a peripheral venous catheter, peripheral venous line, peripheral venous access catheter, or peripheral intravenous catheter, is a catheter (small, flexible tube) placed into a peripheral vein for venous access to administer intrav ...

s and

central venous catheter A central venous catheter (CVC), also known as a central line(c-line), central venous line, or central venous access catheter, is a catheter placed into a large vein. It is a form of venous access. Placement of larger catheters in more centra ...

s. The gauge compared to outer diameter is the same as for needles, but the color coding is different.

References

External links

*{{cite journal , doi=10.1016/0736-4679(87)90009-6 , author=Iserson KV , title=The origins of the gauge system for medical equipment , journal=J Emerg Med , volume=5 , issue=1 , pages=45–8 , year=1987 , pmid=3295010
Sheet Metal Gauge Size Data – Engineers Edge
Wire gauges Standards of the United Kingdom