Gauges, pressure-measuring, types Bourdon-tube

The indicator element measures the signal from the weighing element, and converts it into a readable form. It may be any of several different types, eg, the graduated beam of Figure 3, a Bourdon tube pressure gauge, or a numeric display device. Today (ca 1997), with the increase in automation, the indicator element may not display the weight but may instead transmit it electronically to a controller. 

Conditions of Use Bourdon tubes shoula not be exposed to temperatures over about 65°C (about 150°F) unless the tubes are specifically designed for such operation. When the pressure of a hotter fluid is to be measured, some type of hquid seal should be used to keep the hot fluid from the tube. In using either a Bourdon or a diaphragm gauge to measure gas pressure, if the gauge is below the... 

We measured flow rate with a Varlan P/N 29-000086-00 Soap Bubble Meter. The pressure gauges were Heise bourdon-tube type with 0.1 psla divisions. The column was 16 feet of 1/4 inch copper tubing packed with Carbowax 20M loaded to 20% on Fluoropak 90. 

Bourdon gauges are used on gas cylinders and are also considered a type of aneroid gauge. These devices have a coiled tube (shown in Figure 3.5) and are used to measure the pressure difference between the pressure exerted by the gas in a cylinder and the atmospheric pressure. The coiled tube is mechanically coupled to a pointer (shown in red). As a gas at a pressure above atmospheric pressure enters the coiled tube, it causes it to slightly uncoil, kind of like those New Year s Eve paper noisemakers. This causes the pointer to move over a numerical scale, thereby indicating the gauge pressure in the tank. 

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