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How to choose the right valve
Time：2019/5/7 16:22:19
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First, let's take a look at what the valve does.
In fluid piping systems, valves are control elements whose primary function is to isolate equipment and piping, regulate flow, prevent backflow, regulate and drain pressure. Since it is important to select the most suitable valve for the piping system, it is important to understand the characteristics of the valve and the steps and basis for selecting the valve.
Secondly, let's take a look at what materials are available in the valve.
Valve bearing material cast copper, cast iron, ductile iron, high silicon cast iron, cast steel, forged steel, high (low) alloy steel, stainless acid resistant steel, Hastelloy, Inconel, Monel, duplex Stainless steel, titanium alloy, etc. And can produce a variety of electric, pneumatic, hydraulic valve drive devices.
In the face of so many valve types and complex various working conditions, we should choose the most suitable valve products for the piping system. How do we start?
First of all, we should understand the characteristics of the valve; secondly, we should master the steps and basis for selecting the valve; in addition, we should follow the principle of selecting the valve.
So, what are the characteristics of the valve? There are two general characteristics of the valve, the use characteristics and structural characteristics.
1. Use characteristics: It determines the main performance and scope of use of the valve. It belongs to the valve use characteristics: valve type (closed valve, regulating valve, safety valve, etc.); product type (gate valve, globe valve, butterfly valve, ball valve) Etc); the main parts of the valve (valve body, valve cover, valve stem, valve flap, sealing surface) material; valve transmission and so on.
2, structural characteristics: It determines some structural characteristics of the valve installation, maintenance, maintenance and other methods, belonging to the structural characteristics: the structural length and overall height of the valve, the connection with the pipe (flange connection, threaded connection, clamp Hoop connection, external thread connection, welding end connection, etc.); form of sealing surface (insert ring, thread ring, surfacing, spray welding, valve body); valve stem structure (rotating rod, lifting rod).
The steps and basis for selecting a valve are as follows:
First, the selection step
1. Defining the purpose of the valve in the equipment or device, determining the working conditions of the valve: applicable medium, working pressure, working temperature, etc.
2. Determine the nominal diameter and connection method of the pipe connected to the valve: flange, thread, welding, etc.
3. Determine the way to operate the valve: manual, electric, electromagnetic, pneumatic or hydraulic, electrical linkage or electro-hydraulic linkage.
4. Determine the material of the casing and internal parts of the selected valve according to the medium, working pressure and working temperature of the pipeline: gray cast iron, malleable cast iron, ductile iron, carbon steel, alloy steel, stainless acid-resistant steel, copper alloy, etc.
5. Select the type of valve: closed-circuit valve, regulating valve, safety valve, etc.
6. Determine the type of valve: gate valve, globe valve, ball valve, butterfly valve, throttle valve, safety valve, pressure reducing valve, steam trap, etc.
Second, the basis for selecting the valve
While understanding the steps to master the valve, you should further understand the basis for selecting the valve.
1. The purpose of the selected valve, the working conditions and the control method.
2, 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 flammable, explosive medium, the viscosity of the medium and so on.
3, the requirements of the valve fluid characteristics: flow resistance, discharge capacity, flow characteristics, sealing level and so on.
4, installation size and dimensions requirements: nominal diameter, connection with the pipe and connection size, size or weight restrictions.
5. Additional requirements for the reliability, service life and explosion-proof performance of the valve.
(When selecting parameters, note that if the valve is to be used for control purposes, the following additional parameters must be determined: method of operation, maximum and minimum flow requirements, pressure drop for normal flow, pressure drop at shutdown, maximum and minimum inlet for valve pressure.)
According to the above-mentioned basis and steps of selecting the valve, the internal structure of each type of valve must be well understood in order to properly and correctly select the valve, so that the correct choice can be made for the preferred valve.
In fluid piping systems, valves are control elements whose primary function is to isolate equipment and piping, regulate flow, prevent backflow, regulate and drain pressure. Since it is important to select the most suitable valve for the piping system, it is important to understand the characteristics of the valve and the steps and basis for selecting the valve.
Secondly, let's take a look at what materials are available in the valve.
Valve bearing material cast copper, cast iron, ductile iron, high silicon cast iron, cast steel, forged steel, high (low) alloy steel, stainless acid resistant steel, Hastelloy, Inconel, Monel, duplex Stainless steel, titanium alloy, etc. And can produce a variety of electric, pneumatic, hydraulic valve drive devices.
In the face of so many valve types and complex various working conditions, we should choose the most suitable valve products for the piping system. How do we start?
First of all, we should understand the characteristics of the valve; secondly, we should master the steps and basis for selecting the valve; in addition, we should follow the principle of selecting the valve.
So, what are the characteristics of the valve? There are two general characteristics of the valve, the use characteristics and structural characteristics.
1. Use characteristics: It determines the main performance and scope of use of the valve. It belongs to the valve use characteristics: valve type (closed valve, regulating valve, safety valve, etc.); product type (gate valve, globe valve, butterfly valve, ball valve) Etc); the main parts of the valve (valve body, valve cover, valve stem, valve flap, sealing surface) material; valve transmission and so on.
2, structural characteristics: It determines some structural characteristics of the valve installation, maintenance, maintenance and other methods, belonging to the structural characteristics: the structural length and overall height of the valve, the connection with the pipe (flange connection, threaded connection, clamp Hoop connection, external thread connection, welding end connection, etc.); form of sealing surface (insert ring, thread ring, surfacing, spray welding, valve body); valve stem structure (rotating rod, lifting rod).
The steps and basis for selecting a valve are as follows:
First, the selection step
1. Defining the purpose of the valve in the equipment or device, determining the working conditions of the valve: applicable medium, working pressure, working temperature, etc.
2. Determine the nominal diameter and connection method of the pipe connected to the valve: flange, thread, welding, etc.
3. Determine the way to operate the valve: manual, electric, electromagnetic, pneumatic or hydraulic, electrical linkage or electro-hydraulic linkage.
4. Determine the material of the casing and internal parts of the selected valve according to the medium, working pressure and working temperature of the pipeline: gray cast iron, malleable cast iron, ductile iron, carbon steel, alloy steel, stainless acid-resistant steel, copper alloy, etc.
5. Select the type of valve: closed-circuit valve, regulating valve, safety valve, etc.
6. Determine the type of valve: gate valve, globe valve, ball valve, butterfly valve, throttle valve, safety valve, pressure reducing valve, steam trap, etc.
Second, the basis for selecting the valve
While understanding the steps to master the valve, you should further understand the basis for selecting the valve.
1. The purpose of the selected valve, the working conditions and the control method.
2, 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 flammable, explosive medium, the viscosity of the medium and so on.
3, the requirements of the valve fluid characteristics: flow resistance, discharge capacity, flow characteristics, sealing level and so on.
4, installation size and dimensions requirements: nominal diameter, connection with the pipe and connection size, size or weight restrictions.
5. Additional requirements for the reliability, service life and explosion-proof performance of the valve.
(When selecting parameters, note that if the valve is to be used for control purposes, the following additional parameters must be determined: method of operation, maximum and minimum flow requirements, pressure drop for normal flow, pressure drop at shutdown, maximum and minimum inlet for valve pressure.)
According to the above-mentioned basis and steps of selecting the valve, the internal structure of each type of valve must be well understood in order to properly and correctly select the valve, so that the correct choice can be made for the preferred valve.