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Small knowledge - valve performance
The sealing performance
Valve sealing performance refers to the sealing parts of the valve to prevent the ability of medium leakage, it is the most important technical performance indicators of the valve.
There are three sealing parts of the valve: the contact between the opening and closing parts and the two sealing surfaces of the valve seat;
Mating of packing with stem and stuffing box;
Body to bonnet joint.
The leak in the first place is called an internal leak, which is commonly referred to as loose closure and affects the valve's ability to cut off the medium.
For truncation valves, internal leakage is not allowed.
The latter two leakage is called external leakage, that is, the medium from the valve leakage outside the valve.
External leakage will cause material loss, environmental pollution, and even cause accidents in serious cases.
Flammable, explosive, toxic or radioactive media, leakage is not allowed, so the valve must have a reliable sealing performance.
The flow of medium
The medium flow through the valve will produce a pressure loss (both the valve before and after the pressure difference), that is, the valve has a certain resistance to the flow of medium, medium to overcome the resistance of the valve will consume a certain amount of energy.
In terms of energy saving, the design and manufacture of the valve should reduce the resistance of the valve to the flow medium as much as possible.
Opening and closing force and opening and closing moment
Opening and closing force and moment refer to the force or torque that must be applied to open or close the valve.
Close the valve, the need to make the open-close part and send a form a seal between the two sealing surface pressure, but also overcome between stem and packing, the valve stem and between threads of the nut, valve rod end bearing friction and other parts of the friction force, and therefore must exert closing force and close moment, in the process of opening and closing, the valve is required for opening and closing force and the open-close torque changes, its maximum is in the closed end transient or open the initial transient.
Valves should be designed and manufactured to minimize closing forces and torque.
Opening and closing speed
The speed of opening and closing is expressed as the time required for the valve to complete a single open or close operation.
Generally, there is no strict requirement for the opening and closing speed of the valve, but some working conditions have special requirements for the opening and closing speed, such as some requirements for quick opening or closing to prevent accidents, some requirements for slow closing to prevent water hammer, etc., which should be considered when selecting the valve type.
Sensitivity and reliability
This refers to the valve medium parameters change, make the corresponding response to the sensitivity.
For throttle valves, pressure reducing valves, regulating valves and other valves used to adjust medium parameters and safety valves, traps and other valves with specific functions, its functional sensitivity and reliability is very important technical performance indicators.
The service life of the
It represents the durability of the valve, is an important performance index of the valve, and has great economic significance.
Usually in order to ensure that the closure of the opening and closing of the requirements can also be expressed in the use of time.
Valve sealing performance refers to the sealing parts of the valve to prevent the ability of medium leakage, it is the most important technical performance indicators of the valve.
There are three sealing parts of the valve: the contact between the opening and closing parts and the two sealing surfaces of the valve seat;
Mating of packing with stem and stuffing box;
Body to bonnet joint.
The leak in the first place is called an internal leak, which is commonly referred to as loose closure and affects the valve's ability to cut off the medium.
For truncation valves, internal leakage is not allowed.
The latter two leakage is called external leakage, that is, the medium from the valve leakage outside the valve.
External leakage will cause material loss, environmental pollution, and even cause accidents in serious cases.
Flammable, explosive, toxic or radioactive media, leakage is not allowed, so the valve must have a reliable sealing performance.
The flow of medium
The medium flow through the valve will produce a pressure loss (both the valve before and after the pressure difference), that is, the valve has a certain resistance to the flow of medium, medium to overcome the resistance of the valve will consume a certain amount of energy.
In terms of energy saving, the design and manufacture of the valve should reduce the resistance of the valve to the flow medium as much as possible.
Opening and closing force and opening and closing moment
Opening and closing force and moment refer to the force or torque that must be applied to open or close the valve.
Close the valve, the need to make the open-close part and send a form a seal between the two sealing surface pressure, but also overcome between stem and packing, the valve stem and between threads of the nut, valve rod end bearing friction and other parts of the friction force, and therefore must exert closing force and close moment, in the process of opening and closing, the valve is required for opening and closing force and the open-close torque changes, its maximum is in the closed end transient or open the initial transient.
Valves should be designed and manufactured to minimize closing forces and torque.
Opening and closing speed
The speed of opening and closing is expressed as the time required for the valve to complete a single open or close operation.
Generally, there is no strict requirement for the opening and closing speed of the valve, but some working conditions have special requirements for the opening and closing speed, such as some requirements for quick opening or closing to prevent accidents, some requirements for slow closing to prevent water hammer, etc., which should be considered when selecting the valve type.
Sensitivity and reliability
This refers to the valve medium parameters change, make the corresponding response to the sensitivity.
For throttle valves, pressure reducing valves, regulating valves and other valves used to adjust medium parameters and safety valves, traps and other valves with specific functions, its functional sensitivity and reliability is very important technical performance indicators.
The service life of the
It represents the durability of the valve, is an important performance index of the valve, and has great economic significance.
Usually in order to ensure that the closure of the opening and closing of the requirements can also be expressed in the use of time.
