1. Strength performance
The strength performance of the valve refers to the ability of the valve to withstand the pressure of the medium. Valves are mechanical products subject to internal pressure, so they must have sufficient strength and rigidity to ensure long-term use without cracking or deformation.
2. Sealing performance
The sealing performance of the valve refers to the ability of each sealing part of the valve to prevent the leakage of the medium, which is the most important technical performance index 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; the matching place between the packing and the valve stem and stuffing box; The first one is called internal trickle, also known as sleek close, that can affect the capability of device to reducing medium.
For cut-off valves, internal leakage is not allowed. The latter two leaks are called external leakage, that is, the medium leaks from the inside of the valve to the outside of the valve. Out and about leakage will result in material loss, polluting environmental surroundings, even creating serious incidents.
For the explosive, toxic or perhaps radioactive medium, leakage is not allowed. So valves must have a reliable sealing performance.
3. Flow medium
After the medium flows through the valve, there will be a pressure loss (that is, the pressure difference between the front and rear of the valve), that is, the valve has a certain resistance to the flow of the medium, and the medium must consume a certain amount of energy to overcome the resistance of the valve.
From the perspective of energy saving, when designing and manufacturing valves, it is necessary to reduce the resistance of the valve to the flowing medium as much as possible.
4. Opening and closing force and opening and closing torque
Opening and closing force and opening and closing torque refer to the force or torque that must be applied to open or close the valve.
When closing the valve, it is necessary to form a certain sealing specific pressure between the opening and closing parts and the two sealing surfaces of the seat, and at the same time, it is necessary to overcome the gap between the valve stem and the packing, between the threads of the valve stem and the nut, the support at the end of the valve stem and the The friction force of other friction parts, so a certain closing force and closing torque must be applied. During the opening and closing process of the valve, the required opening and closing force and opening and closing torque change, and the maximum value is at the final moment of closing or opening. the first instant of . When designing and manufacturing valves, try to reduce their closing force and closing torque.
5. Opening and closing speed
The opening and closing speed is expressed by the time required for the valve to complete an opening or closing action. Generally, there are no strict requirements on the opening and closing speed of the valve, but some working conditions have special requirements on the opening and closing speed. If some require rapid opening or closing to prevent accidents, some require slow closing to prevent water hammer, etc. This should be taken into account when selecting the valve type.
6. Action sensitivity and reliability
This refers to the sensitivity of the valve to respond to changes in medium parameters. For valves used to adjust medium parameters such as throttle valves, pressure reducing valves, and regulating valves, as well as valves with specific functions such as safety valves and steam traps, their functional sensitivity and reliability are very important technical performance indicators.
7. Service life
It indicates the durability of the valve, is an important performance index of the valve, and has great economic significance. It is usually expressed by the number of opening and closing times that can guarantee the sealing requirements, and it can also be expressed by the use time.
8. Type
Classification of valves by use or main structural features
9. Model
The valves are numbered according to type, transmission mode, connection form, structural features, material of valve seat sealing surface and nominal pressure, etc.
10. Connection dimensions
Dimensions of valves and piping connections
11. Main dimensions (general dimensions)
The opening and closing height of the valve, the diameter of the handwheel, and the connection size, etc.
12. Type of connection
Various methods (such as flange connection\thread connection\welding connection, etc.)
13. Seal test
A test to verify the performance of the opening and closing parts and the sealing pair of the valve body.
14. Back seal test
A test to verify the sealing performance of the valve stem and bonnet sealing pair.
15. Seal test pressure
The pressure specified when the valve is subjected to a sealing test.
16. Suitable medium
The medium to which the valve can be applied.
17. Suitable temperature
The temperature range of the medium that the valve is suitable for.
18. Sealing face
The two contact surfaces of the opening and closing parts and the valve seat (valve body) are tightly fitted and act as a seal.
19. Opening and closing parts (disc)
A general term for a part used to cut off or regulate the flow of a medium, such as a gate in a gate valve, a disc in a throttle valve, etc.
20. Packing
Packed into the stuffing box (or stuffing box) to prevent the medium from leaking from the valve stem.
21. Packing seat
Parts that support the packing and keep the packing sealed.
22. Packing gland (gland)
Parts used to compress packing to achieve sealing.
23. Bracket (yoke)
On the bonnet or valve body, it is used to support the stem nut and the parts of the transmission mechanism.
24. Dimension of connecting channel
The structural dimensions of the opening and closing parts and the valve stem assembly connection.
25. Flow area
Refers to the minimum cross-sectional area (but not the "curtain" area) between the inlet end of the valve and the sealing surface of the valve seat, used to calculate the theoretical displacement without any resistance.
26. Flow diameter
The diameter corresponding to the flow area.
27. Flow characteristics
In a steady flow state, when the inlet pressure and other parameters remain unchanged, the function relationship between the outlet pressure of the pressure reducing valve and the flow rate.
28. Flow characteristics derivation
In a steady flow state, when the inlet pressure and other parameters remain unchanged, the outlet pressure change value caused by the change of the flow rate of the pressure reducing valve.
29. General valve
Valves commonly used in pipelines in various industrial enterprises.
30. Self-acting valve
A valve that operates by itself depending on the ability of the medium (liquid, air, steam, etc.).
31. Actuated valve
A valve operated manually, electrically, hydraulically or pneumatically.
32. Hammer blow handwheel
A handwheel structure that uses impact force to reduce valve operating force.
33. Worm gear actuator (wormgear actuator)
A device that uses a worm gear mechanism to open and close or adjust a valve.
34. Pneumatic actuator
The driving device that opens and closes or regulates the valve with pneumatic pressure.
35. Hydraulic actuator
A drive that opens, closes or regulates a valve with hydraulic pressure.
36. Hot condensate capacity
The maximum amount of condensate that can be discharged from trap one under a given pressure difference and temperature
37. Steam loss
The amount of fresh steam leaked from the steam trap per unit time.