As a result, this type of stainless steel tubing is usually formed into hypodermic needles for medical applications. It is a slender, hollow, cylindrical length of stainless steel, typically 316 or 304 grade, with a puncturing point made at one end to form a needle.
In terms of needle applications, there are a variety of diameters of hypodermic tubing that work best for certain requirements. For instance, large diameter hypodermic tubing are used for blood donation because the wideness of the needle allows for the removal of blood at a much quicker pace than would be allowed by an average or small diameter hypodermic tube.
Small diameter hypodermic tubing, on the other hand, should not be used for blood donations because the small size of the needle will rupture the red blood cells and make the blood unable to be utilized by recipients. In addition to needle applications, hypodermic tubing is also utilized for spacers, hypodermic guide wires, cannulas and hypodermic capillary tubing in the medical, mechanical, electronic, chemical and aeronautical industries.
Hypodermic tubing is differentiated from other types of tubing by its own set of gauge sizes. For example, fractional tubing is measured by outside diameter and wall thickness, using common fraction sizes like 1/4″ outside diameter combined with a .035″ wall thickness. Hypodermic tubing comes in thin, regular and heavy wall varieties. Hypodermic tubing may be offered in 6″, 12″, 24″ or 36″ lengths. However, hypodermic tubing, or needle tubing, is categorized by gauges, which are determined by the outside diameter and the inside diameter of the tube.
Hypodermic tubing can range from .005″ to .259″ outside diameter and .002″ to .239″ inside diameter. Hypodermic tubing gauges are generally found numbered between 3 and 35, the smaller the number, the larger the diameters. For medical applications, the largest usable gauge size is 7, while the smallest usable gauge size is 33.
Hypodermic tubing gauges are rooted in the Birmingham Gage, which is otherwise known as Stub’s Iron Wire Gage and also measures the thicknesses of pipes. Hypodermic tubing manufacturers should have gauge size charts available to assist in deciding which type of hypodermic tubing is needed for a specific application.