Valves, as important equipment for controlling the flow of media in pipelines, have a series of professional terms to describe their performance, structure, function and classification. The following is a detailed analysis of the professional terms of valves:

I. Basic Definitions and Classifications

Valve:

Definition: The overall mechanical product with a movable mechanism used to control the flow of medium in a pipeline.

Function: Open and close pipelines, control flow direction, and regulate and control the parameters of the conveyed medium (temperature, pressure and flow rate).

Type:

Classified by application or main structural features, such as gate valves, globe valves, throttle valves, ball valves, butterfly valves, diaphragm valves, plug valves, check valves, safety valves, pressure reducing valves, etc.

Ii. Performance Parameters

Strength performance:

Definition: The ability of a valve to withstand the pressure of the medium.

Importance: Valves are mechanical products that withstand internal pressure and must have sufficient strength and rigidity to ensure long-term use without cracking or deformation.

Sealing performance:

Definition: The ability of each sealing part of a valve to prevent the leakage of the medium.

Sealing part: The contact area between the two sealing surfaces of the opening and closing part and the valve seat; The mating points of packing with valve stem and stuffing box; The connection between the valve body and the valve cover.

Leakage types: Internal leakage (affecting the ability to cut off the medium) and external leakage (causing material loss, polluting the environment, and even triggering accidents).

Flowing medium

Definition: After the medium flows through the valve, pressure loss (the pressure difference before and after the valve) will occur, that is, the valve has a certain resistance to the flow of the medium.

Importance: Considering energy conservation, when designing and manufacturing valves, efforts should be made to minimize the resistance of the valves to the flowing medium as much as possible.

Opening and closing force and opening and closing moment:

Definition: The force or moment that must be applied to open or close a valve.

Influencing factors: When closing the valve, it is necessary to form a certain sealing specific pressure between the two sealing surfaces of the opening and closing part and the valve seat, and overcome the friction force between the valve stem and the packing, as well as between the valve stem and the nut and other friction parts.

Opening and closing speed:

Definition: The time required for a valve to complete one opening or closing action.

Importance: Generally, there are no strict requirements for the opening and closing speed of valves, but some working conditions have special requirements for the opening and closing speed.

Action sensitivity and reliability:

Definition: The sensitivity of a valve to changes in medium parameters.

Importance: For valves with specific functions such as throttle valves, pressure reducing valves, and control valves, their functional sensitivity and reliability are very important technical performance indicators.

Service life:

Definition: The durability of the valve.

It is usually expressed by the number of times it can be opened and closed to ensure the sealing requirements, and can also be expressed by the usage time.

Iii. Structure and Components

Opening and closing parts (Disc) :

Definition: A general term for parts used to cut off or regulate the flow of media, such as the gate plate in a gate valve and the disc in a throttle valve.

Packing:

Definition: The filler placed in the stuffing box (or stuffing box) to prevent the medium from leaking from the valve stem.

Packing Seat

Definition: A part that supports the packing and maintains the packing seal.

Packing Gland:

Definition: A part used to press the packing to achieve a seal.

Yoke:

Definition: A part on the valve cover or valve body used to support the valve stem nut and the transmission mechanism.

Dimension of Connecting Channel:

Definition: The structural dimensions of the assembly and connection parts between the opening and closing parts and the valve stem.

Flow Area and Flow Diameter:

Definition: It refers to the minimum cross-sectional area from the inlet end of the valve to the sealing surface of the valve seat and its corresponding diameter, which is used to calculate the theoretical displacement when there is no resistance influence.

Iv. Tests and Standards

Seal Test:

Definition: A test for inspecting the performance of the opening and closing parts and the sealing pair of the valve body.

Upper Seal Test (Back Seal Test)

Definition: A test for inspecting the sealing performance of the valve stem and valve cover sealing pair.

Seal Test Pressure:

Definition: The specified pressure when a valve undergoes a sealing test.

Suitable Medium and Suitable Temperature:

Definition: The medium to which the valve can be applied and its temperature range.

V. Other Terms

Structural length (face-to-face Dimension, face-to-centre Dimension) : The distance between the inlet and outlet end faces of the valve, or the distance from the inlet end Face to the outlet axis.