Basic terminology

1. Strength performance

The strength performance of the valve describes its capacity to bear the medium’s pressure. Since valves are mechanical items that are subject to internal pressure, they need to be strong and stiff enough to be used over an extended period of time without breaking or deforming.

2. Sealing performance

The most significant technical performance index of the valve is its sealing performance, which measures how well each sealing component of the valve prevents medium leakage.

The valve has three sealing components: the connection between the valve body and bonnet; the contact between the opening and closing components and the two sealing surfaces of the valve seat; and the matching location between the packing and the valve stem and stuffing box. The first one, known as internal trickle or sleek close, can impact a device’s capacity to reduce medium.

Internal leaking is not allowed in cut-off valves. The last two breaches are referred to as external leakage because the medium seeps from inside the valve to outside the valve in these instances. Leaks that occur while they are in the open will cause material loss, environmental pollution, and potentially serious accidents.

Leakage is not acceptable for material that is flammable, explosive, toxic, or radioactive, hence the valve needs to work reliably when sealing.
3. Flow medium

Because the valve has a certain resistance to the flow of the medium, there will be a pressure loss after the medium passes through it (i.e., the difference in pressure between the front and back of the valve). The medium must expend energy to overcome the valve’s resistance.

When designing and producing valves, it is important to minimize the valve’s resistance to the flowing liquid in order to conserve energy.

4. Opening and closing force and opening and closing torque

The force or torque required to open or close the valve are referred to as the opening and closing torque and force, respectively.
When closing the valve, a certain closing force and closing torque must be applied in order to create a specific sealing pressure between the opening and closing parts and the two sealing surfaces of the seat, as well as to bridge the gaps between the valve stem and the packing, the threads of the valve stem and the nut, and the support at the end of the valve stem and the friction force of other friction parts.

The needed opening and closing force and opening and closing torque change as the valve opens and closes, reaching their maximum at the last moment of closure or opening. the initial moment of. Try to minimize the closing force and closing torque of valves while designing and producing them.

5. Opening and closing speed

The time needed for the valve to perform an opening or closing movement is used to represent the opening and closing speed. Although there are some operating situations that have specific criteria for the opening and shutting speed of the valve, generally speaking there are no precise limits. Some doors must open or close quickly to prevent accidents, while others must close slowly to prevent water hammer, etc. When choosing the type of valve, this should be taken into consideration.

6. Action sensitivity and reliability

This is a reference to the valve’s responsiveness to changes in the properties of the medium. Their functional sensitivity and dependability are crucial technical performance indicators for valves used to alter medium parameters, such as throttle valves, pressure lowering valves, and regulating valves, as well as valves with specific functions, such as safety valves and steam traps.

7. Service life

It provides insight into the valve’s longevity, serves as a key performance indicator for the valve, and is extremely significant economically. It can also be indicated by the amount of time that it is in use. It is typically expressed by the number of opening and closing times that can ensure the sealing requirements.

8. Type

Valve classification based on function or key structural characteristics

9. Model

The quantity of valves based on the type, transmission mode, connection type, structural characteristics, material of the valve seat sealing surface, nominal pressure, etc.

10. The size of the connection
Valve and piping connection dimensions

11. Primary (generic) dimensions

the valve’s opening and closing height, the handwheel’s diameter, the size of the connection, etc.

12. Connection type

a number of techniques (including welding, threading, and flange connection)

13.Seal test

a test to confirm the effectiveness of the valve body’s sealing pair, opening and closing sections, and both.

14.Back seal test

a test to confirm the valve stem and bonnet sealing pair’s ability to seal.

15.Seal test pressure

the pressure required to perform a sealing test on the valve.

16. Appropriate medium

The type of medium that the valve can be used on.

17. Applicable temperature (suitable temperature)

The temperature range of the medium that the valve is suitable for.

18. Sealing face

The opening and closing parts and the valve seat (valve body) are tightly fitted, and the two contact surfaces that play a sealing role.

19. Parts for opening and closing (disc)

a collective word for a component used to stop or control the flow of a medium, such as a gate in a gate valve or a disc in a throttle valve.

19. Packaging

To stop the medium from seeping from the valve stem, place it in the stuffing box (or stuffing box).

21. Seat packing

a component that holds up the packing and maintains its seal.

22. The packing gland

the components used to seal the packaging by compressing it.

23. Bracket (yoke)

It is used to support the stem nut and other transmission mechanism components on the bonnet or valve body.

24. The connecting channel’s size

the joint’s structural measurements between the valve stem assembly and the opening and closing portions.

25. Flow region

is used to compute the theoretical displacement without resistance and refers to the smallest cross-sectional area (but not the “curtain” area) between the valve inlet end and the sealing surface of the valve seat.

26. Flow diameter

corresponds to the runner area’s diameter.

27. Features of the flow

The function relationship between the outlet pressure of the pressure lowering valve and the flow rate exists in the steady flow state, where the inlet pressure and other parameters are constant.

28. Derivation of flow characteristics

When the flow rate of the pressure lowering valve changes in the steady state, the outlet pressure changes even while the inlet pressure and other variables stay constant.

29. General valve

It is a valve that is frequently utilized in pipelines in different industrial settings.

30. Self-acting valve

an independent valve that relies on the capacity of the medium (liquid, air, steam, etc.) itself.