What factors should be considered in the purchase of the globe valve? The globe valve manufacturer and everyone have a look.
1. Use and medium
Clear use scenario: First determine the specific purpose of the globe valve, whether it is used for industrial pipes, water supply and drainage systems, HVAC, or other specific areas. Different application scenarios have different requirements for valve performance and material. For example, industrial pipes may need to withstand higher pressures and temperatures, and have more stringent requirements for valve strength and tightness; The water supply and drainage system pays more attention to corrosion resistance and blockage resistance.
Medium characteristics: Understand the type of medium flowing through the stop valve, such as gas, liquid, steam, etc. If it is a liquid, it is necessary to consider whether it is corrosive, viscous, and whether it contains particle impurities. For corrosive media, it is necessary to choose corrosion-resistant materials, such as stainless steel, copper alloy, etc. For media containing particulate impurities, a valve with good wear resistance should be selected, or a filter should be set in front of the valve.
2. Pressure and temperature
Working pressure: Determine the working pressure required by the stop valve, including normal operating pressure and the maximum possible pressure. The rated pressure of the selected valve should be greater than or equal to the maximum working pressure of the pipeline system to ensure the safety and reliability of the valve during operation. In general, the working pressure of the shut-off valve in industrial pipelines may range from a few mpa to tens of mpa, while the pressure of the water supply and drainage system in civil buildings is relatively low, usually below 1 mpa.
Operating temperature: Select the appropriate stop valve according to the temperature range of the medium. Different materials of the globe valve have different temperature ranges. For example, ordinary cast iron globe valves are suitable for low temperature environments, while high temperature alloy steel globe valves can be used for high temperature steam and other media. The common operating temperature range from low temperature -20℃ to high temperature hundreds of degrees Celsius, such as the temperature in the steam pipeline may reach more than 200℃, need to choose the corresponding temperature grade of the valve.
3. Flow and velocity
Flow requirements: According to the flow requirements of the pipeline system to select the diameter and diameter of the globe valve. Systems with large flow rates need to select a larger diameter stop valve to ensure smooth flow of fluid and reduce pressure loss. The desired valve diameter can be determined by calculating the flow formula Q=vA for the pipeline (Q is the flow rate, v is the flow rate, and A is the cross-sectional area of the pipeline).
Flow rate limit: Considering the flow rate of the fluid in the pipeline, different media and working conditions have certain restrictions on the flow rate. If the flow rate is too high, it may lead to increased valve wear, noise and vibration, and even affect the normal operation of the system. Generally speaking, the flow rate of the liquid is usually about 1-3m/s, and the flow rate of the gas is relatively high, about 10-30m/s, but the specific situation needs to be determined according to the actual situation.
4, size and connection
Size specifications: The size of the globe valve should match the pipeline system, including the caliber, flange size, length of the valve. Ensure that the valve is properly installed on the pipe to avoid installation mismatches. Common globe valve diameters range from DN15 (1/2 inch) to DN300 (12 inch) or larger, depending on the actual pipe size.
Connection method: The common connection method of the globe valve is flange connection, thread connection, welding connection, etc. Flange connection is suitable for large diameter pipelines and occasions that need to be disassembled frequently, with easy installation and good sealing characteristics; Threaded connection is generally used for small diameter pipelines, simple installation, but the tightness is relatively poor; The welded connection has good sealing and strength, and is suitable for high temperature, high pressure and strict requirements.
5. Material and quality
Body material: Select the appropriate body material according to the medium characteristics and working environment. Common materials are cast iron, cast steel, stainless steel, copper and so on. Cast iron material price is low, suitable for general water supply and drainage system; Cast steel material has high strength and can be used for medium and low pressure industrial pipelines; Stainless steel has good corrosion resistance, often used in chemical, food and other industries; Copper material has good thermal conductivity and corrosion resistance, suitable for some special media and small pipe systems.
Sealing material: The sealing performance of the globe valve directly affects its use effect, and the choice of sealing material is crucial. Common sealing materials are rubber, polytetrafluoroethylene (PTFE), metal and so on. Rubber seal has good elasticity and sealing, suitable for low temperature, low pressure and general media; PTFE seal has excellent corrosion resistance and high temperature resistance, often used in chemical industry and other fields; Metal seals have higher strength and high temperature resistance, suitable for high temperature, high pressure and high sealing requirements.
Quality and brand: The choice of well-known brands and reliable quality of the globe valve can ensure the performance and service life of the valve. Check the valve production process, quality inspection report, certification, etc., to understand the quality assurance of the valve. High quality globe valves usually have fine processing technology, good surface quality and reliable sealing performance.
6. Operation and control
Operation mode: The operation mode of the globe valve is manual, electric, pneumatic, etc. The manual globe valve is suitable for occasions where the operating frequency is not high and the control accuracy is not high, and has the characteristics of simple operation and low cost; Electric and pneumatic stop valves are suitable for applications with a high degree of automation, requiring remote control or rapid response, enabling precise flow control and switching operation.
Control requirements: If the system has special requirements for the control of the globe valve, such as the need to control with other equipment to achieve flow regulation, the corresponding function of the globe valve should be selected. For example, in some automated production lines, it may be necessary to cooperate with the PLC control system to achieve precise control and automatic operation of the fluid.
