Home > News > Content
Valve Classification And Its Characteristics
Nov 23, 2017

Valve classification

(1) classification according to material quality

A. non metallic valves: PVC, plastic (steel), Teflon etc..

B. metal valves

A. ferrous metal: iron, steel, stainless steel, alloy steel, etc..

B. non metals: aluminum, copper, etc..


(2) path classification

A. casting valves: sand mold, shell mold, wax removal mold, die casting and other manufacturing methods, the production of valve parts.

B. forging valves: valve parts manufactured by die forging or free forging or pill (square) material processing.

C. welding manufacturing valves: body and cover are made by several parts of welding, such valves must pay attention to welding procedure specification and identification (WPS and PQR).

D. injection molding valves: generally used in PVC, plastic to be made of non-metallic valves.

(3) valve according to its function, classified as follows:

A. switch valves: gate valve, plug valve, ball valve.

B. throttle valve: ball valve, needle valve, angle valve, disc valve, diaphragm valve.

C. check valve type: swing, lift and two-piece check valve, bottom valve.

D. pressure control valves: relief valve, release valve, safety valve.

E. special valves:

A. sampling valve

B. flow control valve

C. emission valve

D. other kinds of valves


3. valve characteristics

(1) gate valve (GATE VALVES)

The valve is in a position in a pipeline system need to "fully open, fully closed" control and fluid flow only to the low pressure drop have sometimes used in the design. When a part of a system needs isolation, and without considering the control of fluid throttling (THROTTING), the gate valve is ideal and suitable. When the throttle is used, the fluid will flow through the gate seat at high speed, resulting in the erosion of the fluid, the door, seat and shell (wire drawing phenomenon), or damage caused by vibration.


(2) ball valve (GLOBE VALVES), angle valve (ANGLE VALVES), needle valve (NEEDLE VALVE)

Ball valve for ball ball column shape and called, is mainly to be closed, and often switch when the fluid flow control to throttle function and design, is the main characteristic of effective throttling, to minimize and reduce the phenomenon of drawing valve and valve seat dip (wash) inhibition, but because of the seat is parallel to the line, change the flow of fluid through the valve seat class, will produce turbulent flow in the valve, and the decline in force, not only for the Heqiuyin pressure head caused by time, can be used.


The structure of the angle valve is modified by the spherical valve, which is only the difference between the angle of 90 degrees of the exit and the center of the inlet valve.


The needle valve is also modified by a plug ball valve. The valve plug is slender and tapered needle. It is especially suitable for flow control in low flow range.


(3) check valve (CHECK VALVES) - (SWING TYPE), the swing type lift (LIFT TYPE), swash plate (door) type (TILTING DISC), double chip (DUALPLATE), valve (FOOT VALVES).

This kind of valve whose role is to allow the free flow of fluid towards one direction, while restrictions on their anti flow through the system when the fluid pressure, the valve open, any reverse flow, the valve will close, close, Lai is the only body weight back to back pressure or rely on, or a combination of Lai springs or on several.


(4) ball stop check valve (GLOBE STOP-CHECK VALVES)

Check valve is similar to the 3.3 lift check valve, but with valve stem and hand transmission (or other auxiliary operating device) as the fluid shutoff and check, the check valve can not be opened in any mechanical way, only by upstream fluid pressure lift valve, leaving the seat surface.


(5) plug valve (PLUG VALVES)

The valve body by the insertion of the valve plug (door), as with a taper slot to plug the middle piece is named, the simple structure of an ancient type of valve, from fully open to 90 degrees off can only turn the valve plug (door) like I can be of any size and shape, can be made into porous type with three or four lines to connect, and can have different combinations of flow. Generally used for open and close, not to throttle use (unless a special diamond shaped opening and processed).


(6) ball valve (BALL VALVE)

Ball valve is modified by plug valve, with ball plug instead of plunger, to control the liquid, valve plug (door) channel cross-sectional area, and the diameter of the pipeline is the same, the fluid straight through the valve body, and suction has a small pressure drop. Now generally use PTEE, EPDM and other materials, as the valve seat, therefore, the bubble sealing is good. And improved for fire and anti-static safety design, is widely used, but because the valve seat is PTFE material, its use temperature is generally limited to below 250 degrees.