Pneumatic valve on the steam pipe

No specific requirements; normal instrument air (air pressure greater than 0). 5Mpa is sufficient.

Installation of steam pressure relief valves: 1. The installation method can involve the diaphragm being located above or below the pipeline, or it can be installed on a vertical pipeline. Before installation, ensure that the ends of the pipes are reamed and that the thread length is cut appropriately. Blow air out to remove any loose oxide layers or other foreign substances in the pipeline that could damage the valve seat. 2. Install a control valve on the pipeline, ensuring that the arrow on its body points in the direction of fluid flow. 3. As shown in the diagram, connect a DN6 or DN10 balance tube from the diaphragm chamber to a location at least 18 inches away from the pressure-reducing tube; it is better to place it even further away from the control valve. Note: In steam applications, if the control valve is installed above the pipeline or on a vertical pipeline, the control pipeline must have a return path to create a water seal and prevent steam from coming into contact with the diaphragm. 4. Install a needle valve on the control pipeline. If unstable pressure causes fluctuations in the control valve, these fluctuations are stabilized through throttling by the valve. Note: On pressure safety valves, a chamber with a diameter of 15 inches is standard; the factory setting is 60 psi to prevent excessive pressure in the chamber. A discharge pipe should be connected to the safety valve to direct any potential emissions to the installation site where they can be disposed of. Note: In steam applications, if the valve is installed above a horizontal pipe or on a vertical pipe, a balance tube must be provided to create a water-sealing circuit. Note: As shown in the diagram. The balance tube must always be installed within the DC section of the pipeline.

Of course, the most important factor to pay attention to is temperature, as it relates to: 1. The temperature-pressure curve of the valve material, which needs to be taken into account； 2. The material of the valve internals must be able to withstand high temperatures ； 3. For the sealing material of the valve, it is necessary to consider whether graphite should be used ； 4. If the temperature is too high, domestic valves require a heat-dissipation extension neck ； 5. As with ordinary valves, pay attention to whether the pressure difference before and after is within the valve’s tolerance.

3-5 kilograms of compressed air is sufficient, mainly to overcome the friction between the valve core and the valve body. The lever arm driven by compressed air is much larger than the lever arm of the frictional resistance between the valve core and the valve body; steam pressure does not need to be considered.

In the documents on the 3rd floor, the air supply for the steam control valve is regulated using the steam pressure that has passed through that valve. The air supplies for control valves that I’ve seen are part of separate systems designed for instrument use – is there any difference between the two?

There are likely to be requirements, such as pipeline pressure and temperature, as well as whether acidity or alkalinity is present; these factors have a direct impact on the selection of valves and the materials used for them.