Why pressure gauge below the pipe to make a bend? We must perform strength and leakage tests when the equipment and piping are made. When testing the pressure, we need to use the pressure gauge. You may have noticed, but the connection between the pressure gauge and the equipment and piping is bent.
The following is the name and role of the bend. The bend below the pressure gauge is called the pressure gauge buffer pipe. The builder customarily called the pressure gauge pipe bend. It has two forms. One is a ring bend. The other is a U-shaped bend. The latter name is more intuitive and apt.
This seemingly insignificant design serves a great purpose. It is a polytechnical design with a role that should not be underestimated, including the following two aspects. On the one hand, it protects the gauge from being damaged by excessive pressure. On the other hand, it ensures the accuracy of the meter’s measured values.
1. Pressure Gauge Bend
The pressure gauge bend is an accessory to connect the pressure gauge to the equipment or piping between which the indicator is measured. It is used to cushion the measured medium’s transient impact on the pressure gauge’s spring tube. At the same time, it can reduce the temperature of the measured medium and is a device for the protection of the pressure gauge.
A pressure buffer tube is a pressure buffer. In pipeline transport, the substance can be a liquid or a gas, both of which are subject to fluid pressure.
2. The Role of the Pressure Gauge Bend
2.1 Protective Function
The same principle as the pressure gauge bend is used abroad for pressure relief holes. With the help of these simple designs, better pressure gauge protection can be achieved, and the indicator can work properly.
2.2 Cooling Medium Temperature in the Bend
Pressure gauge storage bend that plays the role of buffer fluid, more importantly, plays a cooling role so that steam or higher temperature media in this section of the bend condensation cooling to avoid high-temperature steam or high-temperature media directly into the pressure gauge reed tube, resulting in the table components overheating and deformation, affecting the accuracy of the pressure gauge.
2.3 Condensation Tube Bend
When the measured medium temperature is high, to prevent high-temperature damage to the pressure gauge, access to the condensing bend can reduce the temperature of the instrument joints (need to be less than 70 degrees) or is filled with isolation liquid (not commonly used). However, when the pressure gauge was to measure the liquid, if we installed it in the upper 90 degrees of the condensate tube, so quickly accumulated gas, leading to instrument pointer jitter, but would accelerate the damage to the pressure gauge. Therefore, ambient temperature is not required condensation bend.
3. Changes in the medium being measured
When the pressure of the medium in the pipeline is too high or when there are large fluctuations in the pressure of the transported material, if there is no such pressure buffer tube, it will act directly on the pressure gauge. When the changes are slight, the pressure gauge will only show deviations in its readings, making them inaccurate. In addition, the indicator can be damaged severely, causing repair and replacement problems.
Failure of a pressure gauge can lead to incalculable losses and safety hazards. The role played by the pressure gauge tube bend is to protect the pressure gauge from damage caused by some controllable factors, which can be said to be the crystallization of human wisdom.
4. Application of Pressure Gauges
4.1 The suction pipe of the fire pump should be equipped with a control valve and a pressure gauge. In addition, control valves, non-return valves, and pressure gauges should be provided on the discharge pipe.
4.2 An anechoic non-return valve, control valve, and pressure gauge shall be installed on the discharge pipe of the fire pump. In addition, a pressure gauge and switch shall also be installed on the main outlet pipe of the system.
When a pressure gauge is installed, we shall add a buffer device. A plug should be fitted between the pressure gauge and the buffer. The pressure gauge range should be two times to 2.5 times the working pressure of the system when there is no design requirement.
4.3 The fire pump test pressure gauge should be at least 2. The accuracy should be at least 1.5 grade, and the range should be 1.5 times~2 times the test pressure value.
4.4 The pressure gauge should be set on the fire pump’s suction and discharge pipe and conform to the following regulations.
(1) The maximum range of the pressure gauge of the fire pump discharge pipe should be at least two times its designed working pressure and at least 1.60MPa.
(2) Fire pump suction pipe should be set up vacuum meter, pressure meter, or vacuum pressure meter. The maximum range of the pressure meter should be determined according to the project’s specific conditions but should be at least 0.70MPa. The full range of the vacuum meter should be -0.10MPa.
(3) The diameter of the pressure gauge should be at least 100mm. We should use a pipe with a diameter of not less than 6mm to connect with the import and export pipe of the fire pump and should set the shut-off valve.
4.5 Rain shower alarm valve inlet and outlet should also be set up with a pressure gauge. The pressure gauge should be installed in a position on the alarm valve that is easy to observe.
4.6 Safety relief devices and pressure gauges should be provided on storage containers or container valves in gaseous fire extinguishing systems.
4.7 Pressure gauges for pressure testing of automatic sprinkler systems should be at least 2. Accuracy should be at least 1.5 level. The range should be 1.5 times the test pressure value ~ 2.0 times.
4.8 end of the water test device should be a water test valve, pressure gauge, and water test joints. The flow coefficient of the water test fitting outlet should equal the minimum flow coefficient of the sprinkler head on the same floor or within the fire protection zone.
The water from the end of the water test device should be taken out of the orifice to discharge into the drainage pipe, the drainage riser should be equipped with an extension top ventilation pipe, and the diameter of the line should not be less than 75mm
5. Conclusion
Pressure gauges are generally used in various manufacturing industries, such as hot water and heating supply systems, oil pipeline transport, thermal networks, automotive maintenance, and other aspects. It can be seen that its use is still pervasive.
Failure of the pressure gauge can cause incalculable losses and safety hazards. The role played by the pressure gauge bend is to protect the pressure gauge from damage caused by controllable factors, which can be said to be the crystallization of human wisdom.
