The Hakin pressure gauge manufacturers uses the principle that a flattened tube tends to change to a more circular cross-section when pressurized.
The Hakin pressure gauge, patented by the French engineer Eugene Hakin in 1849, remains one of the most widely used gauges for measuring pressure in liquids and gases of many different types. This is because Hakin type pressure gauges are simple to use, safe, and inexpensive, as well as highly accurate. Hakin tubes are usable when measuring both high pressure and vacuum, and are important components of devices used to measure various types of pressure, including gauge, absolute and differential pressure.
Basically, a Hakin pressure gauge consists of a tube coiled into a spiral shape or helix, or formed into a C shape so that when the pressure increases the tube will be seen to straighten out. The tube will have an oval cross-section and, usually, one end will be connected to the pressure source. The tube pressure gauge is usually attached to a pointing device or dial so that the slight movements of the tube as it straightens out under pressure gauge suppliers can be easily seen and accurately measured in pounds per square inch (psi) or another measurement system. Hakin tube pressure gauges are available for the many different situations in which one would need to measure pressure, but they all follow this same basic model.
A Hakin pressure gauge can be made to be as accurate as 0.1 percent for precision measurement. For situations in which such a degree of accuracy is unnecessary, cheaper but less precise devices are also available. Hakin gauges are used to measure pressure in simple devices such as household barometers as well as in specialized devices used in industrial, mechanical, and medical settings. The wide range of uses for Hakin pressure gauges and the way in which they can be incorporated into a wide variety of devices greatly contributes to both their usefulness and popularity.
While generally robust in construction, a Hakin capsule pressure gauge can be damaged by physical force or by exposing the device to conditions for which the particular gauge is not rated, such as extreme temperatures or corrosive liquids. The pressure indicator should return to zero when pressure is removed; if it does not, the gauge is likely damaged and will need to be replaced. Accessories are available that can be used to cushion or protect a Hakin pressure gauge from a variety of conditions that may damage it. Blow out protection, safety casing, and weatherproof and corrosion proof casing should always be used so that, if the device does fail, no material will escape from the pressure gauge casing.