1. Municipal water supply/sewage treatment industry: full process valve selection

In the municipal water supply system, the main pipes are often operated under conditions of large diameter, high flow rate, and low frequency. Gate valves or large diameter butterfly valves are preferred to ensure water supply efficiency by utilizing their low pressure loss characteristics; Branch pipes and residential entrance pipelines can be equipped with ball valves or small-diameter butterfly valves, which balance sealing and ease of operation; Pump stations require rapid shutdown and emergency control, often using electric butterfly valves or ball valves, in conjunction with automation systems to achieve remote control.

In sewage treatment scenarios, the medium is mostly contaminated and corrosive sewage. Eccentric butterfly valves are preferred for main pipelines, which are more suitable for anti clogging and corrosion resistance; Wear resistant alloy gate valves can be used for sludge conveying pipelines to reduce the erosion and wear of the valve plate by the medium; Stainless steel ball valves can be used in precise control processes such as dosing and disinfection to ensure accurate medium on/off and sealing performance.

2. Petrochemical Industry: Valve Selection and Combination for Chemical Media/Gas Fuel/Crude Oil

The media in the petrochemical industry are complex, ranging from flammable and explosive gases and crude oil to highly corrosive chemical reagents, placing extremely high demands on valve sealing, corrosion resistance, and explosion-proof capabilities.

Gas Fuel Transmission Pipelines: Forged steel ball valves are preferred, as their zero-leakage sealing performance effectively avoids the risk of gas leakage while meeting explosion-proof requirements.

Crude Oil and Refined Oil Transmission: Gate valves or eccentric butterfly valves can be used for large-diameter main pipelines, balancing high flow rates and low resistance; stainless steel ball valves are used for branch lines and metering links to ensure precise control and sealing.

Chemical Media (Acids, Alkalis, Organic Solvents): Valves made entirely of stainless steel or special alloys, such as Hastelloy ball valves or PTFE-lined butterfly valves, must be selected to prevent corrosion of the valve body and seals by the media. The corresponding nominal pressure rating should be selected accordingly.

3. HVAC/Building Water Supply and Drainage Industry: Valve Selection Recommendations for Commercial/Residential Piping

In HVAC systems, chilled water and cooling water circulation pipelines are mostly under medium-to-low pressure and high flow conditions, making butterfly valves the preferred choice. Their compact structure saves space in ceilings or pipe shafts while meeting flow regulation requirements. Steam heating pipelines require cast steel gate valves or high-temperature ball valves to adapt to high-temperature and high-pressure steam conditions and prevent seal aging and failure.

In building water supply and drainage, brass or stainless steel ball valves are often used for inlet branch pipes and kitchen and bathroom pipelines in residential buildings due to their ease of operation and good sealing performance. Fire sprinkler systems in commercial buildings require fire-fighting butterfly valves or gate valves to meet the specifications for rapid shut-off and emergency response. For domestic water supply pipelines, butterfly valves or gate valves can be selected, balancing cost and performance.

4. Power Industry: Valve Selection Considerations for Steam/Cooling Water/Fuel Piping

The power industry operates under complex conditions, and the requirements for valves vary significantly depending on the media being transported.

Steam Piping: High-temperature, high-pressure main steam pipelines must use high-temperature, high-pressure gate valves or forged steel ball valves with a metal hard-seal structure suitable for high-temperature conditions. Auxiliary steam pipelines can use cast steel gate valves, meeting performance requirements while controlling costs. 

Cooling Water Piping: For high-flow-rate circulating cooling water main pipelines, large-diameter butterfly valves are preferred due to their low resistance and low cost advantages. Cooling water branch pipelines can use ball valves or butterfly valves to meet daily regulation and on/off requirements.

Fuel Piping (Fuel Oil, Gas): Wear-resistant gate valves or ball valves are used for fuel oil transportation, while explosion-proof ball valves are mandatory for gas transportation to ensure the safe transport of flammable and explosive media and meet the explosion-proof regulations of the power industry.

In conclusion: valve selection across different industries essentially follows the principle of "prioritizing operating conditions and ensuring suitability." Only by combining industry characteristics, media type, and operational requirements can a valve solution that is both safe and economical be selected.