"The lowest and highest allowable gauges are pre-defined and published tables state the sizing of every available gauge. Attempts have been made to replace the gauge system with a logical, modern system, but have gained no traction until now 1."
"The gauge originally arose as a method for measuring the thickness of metal wire, in particular, iron wire. For centuries, wire was manufactured by a process known as 'drawing'. The process of wire-making started with a thick wire, and thinner wires were made by pulling (or drawing) the wire through progressively smaller holes. The size of the largest wire that one could start with was limited by the force that could be generated to pull it through a smaller hole. In the pre-steam age, the greatest force could be supplied by horse or a water-wheel."
"Each wire-maker would have a standard metal gauge for their customers' use by which they could choose the thickness of wire they might require and also verify that their purchased wire was of the stated size. This system did not require any absolute measurement of the wire thickness. Indeed in the pre-industrial era, technology was not yet sophisticated enough to perform accurate, consistent measuring. This explains why the system is comparative and not absolute."
"However when abbreviated, it is always capitalised, but could be written as "1 G" or "1G". The former seems more common and would square with official practice for other scientific units 1-4, i.e. a space is left between the numeric quantity and the unit symbol, e.g. for distance, we write "1 cm" and not "1cm". The only common exceptions are for the Celsius temperature scale (1°C not 1 °C) and angle measurements (90° not 90 °)."
"However when abbreviated, it is always capitalised, but could be written as "1 G" or "1G". The former seems more common and would square with official practice for other scientific units 1-4, i.e. a space is left between the numeric quantity and the unit symbol, e.g. for distance, we write "1 cm" and not "1cm". The only common exceptions are for the Celsius temperature scale (1°C not 1 °C) and angle measurements (90° not 90 °)."
"When the UK became the first country in the world to standardise a gauge system in 1884, an attempt was made to make the increments between the gauge numbers more regular. This system was known as the British Standard Wire Gauge, and it was developed from the older Birmingham gauge system."
"Although peripheral and central venous catheters use the same measurement for cannula size, the colour system for peripheral venous cannulae is different from the ISO needles above. It uses the ISO 10555-5 which specifies the size and colour of cannulae 6:"
"French gauge (catheter sizing)"
Expected headings
"Needle gauge in medical use"
"Hypodermic needles"
"Venous catheters"
"There is a lack of consistency across the medical literature and more widely about how the gauge should be written 1-4. Using the full form it is straightforward, "1 Gauge" and it is generally capitalised."