How to choose a suitable imported valve correctly

(Summary description)Imported valves mainly refer to valves from foreign brands, mainly European, American and Japanese brands.

Imported valves mainly refer to valves from foreign brands, mainly European, American and Japanese brands. The product types of valves mainly include imported ball valves, imported stop valves, imported regulating valves, imported butterfly valves, imported pressure reducing valves, imported solenoid valves, etc., and There are many parameters such as product caliber, pressure, temperature, material, connection method, operation method, etc. It is necessary to select the appropriate valve according to actual needs and product characteristics.
1. The characteristics of the imported valve include use characteristics and structural characteristics

1. Use characteristics of imported valves

The use characteristics determine the main use performance and scope of the valve. The use characteristics of the valve include: valve category (closed circuit valve, regulating valve, safety valve, etc.); product type (gate valve, globe valve, butterfly valve, ball valve, etc.); valve Material of main parts (valve body, bonnet, valve stem, valve disc, sealing surface); valve transmission mode, etc.

2. Structural characteristics

The structural characteristics determine some structural characteristics of the valve installation, repair, maintenance and other methods. The structural characteristics include: the structural length and overall height of the valve, the connection form with the pipeline (flange connection, threaded connection, clamp connection, external Threaded connection, welding end connection, etc.); the form of the sealing surface (inlay ring, threaded ring, surfacing, spray welding, valve body); valve stem structure (rotating rod, lifting rod), etc.

Second, the steps to select the valve

Clarify the purpose of the valve in the equipment or device, and determine the working conditions of the valve: applicable medium, working pressure, working temperature, etc.; for example, if you want to choose a German LIT stop valve, confirm that the medium is steam, and the working principle is 1.3Mpa, working temperature is 200℃.

Determine the nominal diameter and connection method of the pipeline connected to the valve: flange, thread, welding, etc.; for example, select an inlet stop valve and confirm that the connection method is flanged.

Determine the way to operate the valve: manual, electric, electromagnetic, pneumatic or hydraulic, electro-hydraulic linkage, etc.; for example, the manual shut-off valve is selected.

Determine the material of the selected valve shell and internal parts according to the medium, working pressure and working temperature of the pipeline: cast steel, carbon steel, stainless steel, alloy steel, stainless acid-resistant steel, gray cast iron, malleable cast iron, ductile cast iron, copper Alloy, etc.; such as the cast steel material selected for the globe valve.

Select the type of valve: closed circuit valve, regulating valve, safety valve, etc.;

Determine the valve type: gate valve, globe valve, ball valve, butterfly valve, throttle valve, safety valve, pressure reducing valve, steam trap, etc.;

Determine the parameters of the valve: For automatic valves, first determine the allowable flow resistance, discharge capacity, back pressure, etc. according to different needs, and then determine the nominal diameter of the pipeline and the diameter of the valve seat hole;

Determine the geometric parameters of the selected valve: structural length, flange connection form and size, valve height dimension after opening and closing, connecting bolt hole size and number, overall valve outline size, etc.;

Use existing information: valve product catalogs, valve product samples, etc. to select appropriate valve products.

Third, the basis for selecting valves

The purpose, operating conditions, and control methods of the selected valve;

The nature of the working medium: working pressure, working temperature, corrosion performance, whether it contains solid particles, whether the medium is toxic, whether it is a flammable or explosive medium, the viscosity of the medium, etc.; for example, if you want to choose the imported solenoid valve from LIT, the medium In addition to the flammable and explosive environment, the explosion-proof solenoid valve is generally selected; another example is to choose the ball valve of German Lit LIT. The medium contains solid particles, and the V-shaped hard-sealed ball valve is generally selected.

Requirements for valve fluid characteristics: flow resistance, discharge capacity, flow characteristics, sealing level, etc.;

Requirements for installation dimensions and external dimensions: nominal diameter, connection method and connection dimensions with the pipeline, external dimensions or weight restrictions, etc.;

Additional requirements for valve product reliability, service life, and explosion-proof performance of electric devices (note when selecting parameters: If the valve is to be used for control purposes, the following additional parameters must be determined: operation method, maximum and minimum flow requirements , The pressure drop of normal flow, the pressure drop when closing, the maximum and minimum inlet pressure of the valve).

According to the above-mentioned basis and steps for selecting valves, it is necessary to have a detailed understanding of the internal structure of various types of valves when selecting valves reasonably and correctly, so as to make a correct decision on the preferred valve.

The ultimate control of the pipeline is the valve. The valve opening and closing parts control the flow direction of the medium in the pipeline. The shape of the valve flow path makes the valve have a certain flow characteristic. This must be considered when selecting the most suitable valve for the pipeline system.
Summarize and summarize several major elements of the selection: determine what valve function to choose, confirm the temperature and pressure of the medium, confirm the flow rate of the valve and the required diameter, confirm the material of the valve, and the operation method;