Gauge bend

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The device that connects the pressure gauge to the pipe is known as a pressure gauge elbow (also simply called an elbow); its official name is a buffer tube. It is a fitting used to connect a pressure gauge to the equipment or pipes that it measures pressure in; it serves to cushion the sudden impacts of the medium being measured on the gauge’s spring tube, thereby protecting the mechanical structure of the digital display or the pressure sensor from damage and extending their service life. Tubes are available in many different materials, and to measure various media it is necessary to choose buffer tubes made of appropriate materials in order to ensure accurate measurements and the proper functioning of the measurement system. The scientific name for this elbow is a condenser tube or siphon tube. As stated in section 6.4 of the installation instructions in the HK03 Pressure/Differential Pressure Measurement Instrument Pipeline Connection Manual, version HG/T20581-2012, “for steam and other condensable hot gases, as well as when the medium temperature exceeds 60°C, pressure gauges to be installed on-site should use installation diagrams that include condenser tubes (or siphon tubes). This is done to neutralize the gas medium and prevent damage to the instruments.” Of course, the SH/T3104 Instrument Installation Design Specification also contains similar provisions. There are two types of bends for pressure gauges: one is an annular bend, and the other is a U-shaped bend. The purpose of using a bend for a pressure gauge is to protect the internal mechanisms of the gauge from damage caused by the temperature of the medium and its corrosive properties. Generally, if the medium is somewhat corrosive, a pressure gauge elbow must be installed; it is also necessary to use a pressure gauge elbow when the temperature of the medium exceeds 60°C. If the pressure gauge is installed on a clean potable water system, no additional installation is required. It also helps to reduce vibrations and shocks, and it provides some cooling effect for media at higher temperatures, thereby protecting the pressure gauge and minimizing errors caused by the gauge’s temperature. The damping screws at the connection holes of some pressure gauges serve to provide throttling and buffering effects by reducing the flow area, and they are mainly useful for suppressing pressure pulses in the medium.