Urgent: Please advise, is it better to use pipes with a larger diameter or smaller diameter for compressed air pipelines?

The general pipe diameter is determined based on flow rate and pressure, and should not be considered based on the medium. There might be special circumstances; I hope someone with more experience can offer some advice.

1 The compressed air pipeline should meet the user’s requirements regarding compressed air flow rate, pressure, and quality. The choice of laying method should be determined through technical and economic comparison, taking into account local topographical, geological, hydrological, and meteorological conditions. In plant (mine) areas in hot and warm regions, compressed air pipelines should preferably be installed overhead. In cold-region plant (mine) areas, compressed air pipelines should be laid in the same trench or underground as thermal pipelines. When compressed air pipelines are installed above ground in cold and extremely cold regions, anti-freezing measures should be taken. 2 Pipes for transporting saturated compressed air shall be equipped with devices capable of draining the oil and water accumulated within the piping system. For pipes with a slope, the slope should not be less than 0.002. 3 For compressed air pipeline materials, carbon steel pipes are preferred. For dry and purified compressed air pipelines with a water vapor content of less than 7.98 MG/M^3 and dust particles smaller than 0.5 μM, stainless steel pipes can be used. Note: A water vapor content of 7.98 MG/M^3 in compressed air corresponds to a dew point of -60°C at atmospheric pressure. 4 For isolation valves in dry and purified compressed air pipelines where the water vapor content is less than 7.98 MG/M³ and the dust particles are less than 0.5 μM, stainless steel ball valves or stainless steel bellows valves are recommended. 5 For the connection of compressed air pipelines, except where equipment and valves are connected using flanges or threads, welding is preferred for other sections. The piping connections for transporting dry and purified compressed air shall comply with the relevant provisions of the **current ‘Design Code for Clean Rooms’. Thermal compensation should be considered for the overhead compressed air pipelines in the 6 plant (mine) areas. 7 At the entrance of the building where compressed air is used, a shut-off valve, pressure gauge, and flow meter should be installed in the compressed air pipeline. Oil-water separators should be installed in pipelines transporting saturated compressed air. 8 For users with large fluctuations in compressed air demand or those requiring a stable supply pressure, it is advisable to install air storage tanks or other pressure stabilization devices in close proximity. For the overhead compressed air pipes in Workshop 9, it is advisable to lay them along walls and columns. Its height should not hinder transportation and should facilitate maintenance. 10 When compressed air pipelines need to be grounded for lightning protection, the **current ‘Code for Design of Lightning Protection in Buildings’ shall be followed. 11 Compressed air pipes laid underground should be given appropriate anti-corrosion treatment depending on the corrosivity of the soil. Buried pipelines for transporting saturated compressed air in factory (mine) areas should preferably be laid below the freezing line. When buried compressed air pipelines in industrial zones (mines) pass under railways or roads, the angle of intersection should be no less than 45°, and the distance from the top of the pipeline to the railway track surface should be no less than 1.2 M ； It should be no less than 0.7M from the road surface. For compressed air pipelines laid underground in factory (mine) areas that pass through railways or roads where excavation is difficult, sleeves should be installed. The ends of the casing must extend at least 1 meter beyond the railway embankment or the roadside. If there is a drainage ditch beside the railway or road, it should extend 1 meter beyond the edge of the ditch. The clear distance between the compressed air pipelines in factory (mine) areas and buildings, structures, transportation routes, as well as other pipelines, shall comply with the provisions of the **current \"Code for General Layout Design of Industrial Enterprises\".

1. The determination of pipe size should be based on actual conditions; for a given flow rate, the diameter of the pipes is closely related to the initial investment cost, operating costs, and depreciation costs of the piping system. An economic comparison should be made based on these costs, and the pipe pressure should be kept within the specified operating pressure range in order to select an appropriate pipe diameter; in addition, limitations such as safe flow rates and other conditions must also be taken into account. 2. Based on the reference flow velocity for compressed air provided in chemical engineering handbooks, which is generally between 15 and 20 m/s, the pipe diameter can be calculated using the flow rate Q of compressed air required by the process conditions, and then rounded off.

It is mainly determined by the pressure of the compressed air; the compressed air in my workshop has a pressure of 0.6 MPa, and the pipes are DN50 in size!

The diameter of the compressed air pipeline depends on the flow rate; generally, the flow velocity of compressed air in the pipeline is around 20 meters per second. The corresponding diameter is calculated and then rounded to a standard size.

For compressed air, the pipe diameter is selected to meet the pressure drop requirements

The pipe diameter is determined by taking into comprehensive consideration process parameters such as flow rate and pressure

The diameter of the pipelines for transporting any medium is determined based on the selected flow rate, and the choice of flow rate depends on factors such as the properties of the medium and the operating pressure. Table 25-5 in the Third Edition (Volume 2) of the Chemical Process Design Handbook provides recommended flow rates that can be used (for different media, under different operating conditions, and at different flow rates).

Which standard is this from? . . . . . .

The choice of pipe diameter is related to the flow rate you require. Once your pressure is determined, if a higher flow rate is needed, then a larger diameter pipe is necessary; if a lower flow rate is sufficient, a smaller diameter pipe will do. There is no such thing as which diameter is better – larger or smaller.