Pressure Gauge Classifications

Pressure gauges have a number of applications such as showing depth or altitude or how much gas is present in a tank for example. Pressure gauges are classified into four types; liquid, elastic, electric and piston. Each gets the pressure reading in a different way, and this depends on their use.

  1. Liquid Column

    • A liquid column pressure gauge consists of a u-shaped glass tube partially filled with a liquid such as mercury. The column rises or falls until the weight is in equilibrium with the pressure differential between the two ends of the tube. An example of this is a liquid-filled thermometer. The measurement range of these devices is not so high.

    Elastic

    • Elastic pressure gauges such as Bourdon gauges are constructed using the principle that various elements will become elastically deformed when under pressure. They indicate the difference between the pressure inside the median and the surrounding atmosphere. Examples of elastic pressure gauges include scuba diving analogue air-pressure gauges. The measurement range of these pressure gauges is large and used in many items.

    Electric

    • Electric pressure gauges use one of two methods to read pressure. A combination of strain element and elastic object. They convert the shape change caused by pressure into an electrical signal output such as voltage, current or frequency. They also use the deformation characteristics of the sensor. When the pressure exceeds a preset value, the pressure sensor outputs a signal. The direct electrical signal is then shown on a digital gauge.

    Piston

    • Piston pressure gauges work on the principle of counterbalancing the pressure with a spring. The measurement error of a piston is very small, which makes it an expensive gauge. Common uses for the piston pressure gauge include measuring tire pressure and using it to adjust other gauges.