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Why is there a bend between the pressure gauge and the pipe connection?

Updated: Mar 2, 2021

When a pressure gauge is connected to the pipe, a bend is added between the pressure gauge and the pipe connection. Let’s take a look at why adding the bend is essential and how it works.

The pressure gauge bend (also referred to as the gauge bend or buffer tube) connects the pipe's pressure gauge. This gauge is used to connect the pressure gauge and the pressure gauge measuring equipment or pipe fittings. The gauge buffers the measured medium's immediate impact on the pressure gauge spring tube to protect the digital display or pressure sensor's mechanical structure or pressure sensor from damage and extends service life.

To properly evaluate the true pressure of a system’s piping , it is essential to choose buffer tubes of various materials to ensure the accuracy of the measurement and the regular operation of the measurement system.

According to the HG/T20581-2012 version of the HK03 pressure/differential measuring instrument and the Piping Connection Atlas description 6.4, the installation instructions to manage steam and similar condensable hot gases are as follows:

Suppose the temperature of the medium exceeds 60 degrees Celsius. In that case, the pressure gauge that is installed on-site should use the installation drawing with a condenser or siphon (The scientific name of this elbow is called the condensing pipe or siphon). The purpose is to passivate the gas medium to prevent damage to the instrument. The "SH/T3104" instrument installation design specification also has a similar description.

There are two types of pressure gauge bends: One is a circular bend, and the other is a U-shaped bend.

The purpose of the pressure gauge bend is to protect the gauge’s internal transmission mechanism from the damage of the medium temperature and the medium’s corrosiveness. As a rule, if the medium is corrosive to a certain extent, a pressure gauge bend must be installed. When the medium’s temperature is greater than 60°C, a pressure gauge bend must be installed. If the pressure gauge is installed on a clean drinking water system, there is no need to install it. It also reduces vibration, impact, and heat dissipation on the higher temperature medium. This protects the pressure gauge and minimizes the temperature error on the pressure gauge. The damping screw at the orifice of some pressure gauge joints has a throttling and buffering effect by reducing the flow area, mainly useful for medium pressure pulses.

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