How to classify valves？

With the continuous improvement of the process flow and performance of various complete sets of equipment, the types of valves are also constantly changing and increasing. There are many ways to classify valves. Different classification methods have different results. Several commonly used classification methods are as follows.

Valves can be divided into drive valves and automatic valves according to the driving mode, and drive valves can be divided into manual valves and power-driven valves.

Drive valve

Manual valves are valves that are operated manually with the help of handwheels, handles, levers or sprockets. When the valve opening and closing torque is large, a gear or worm gear reducer can be installed between the handwheel and the valve stem for operation. Manual valve is the most common valve driving method. Generally, the driving force acting on the manual valve handwheel shall not exceed 360N.

Power-driven valves are valves that can be driven by various types of power. Common power-driven valves in the industrial field include electric valves, pneumatic valves, hydraulic valves, gas-liquid linkage valves and electro-hydraulic linkage valves. Electric Valve - A valve operated by an electric device, solenoid, or other electrical device. Pneumatic valve - A valve that is operated by the pressure of air. Hydraulic valve - a valve operated by the pressure of liquid (water, oil and other liquid media). Gas-liquid valve - A valve operated by a combination of gas and liquid pressure. Electro-hydraulic valve - a valve operated by a combination of electric device and body pressure.

automatic valve

A valve that operates on its own based on the energy of the medium (liquid, air, steam, etc.). Such as safety valves, pressure reducing valves, check valves, traps and emergency shut-off valves for LPG tankers, etc.

Valves can be divided into low vacuum valves, medium vacuum valves, high vacuum valves, ultra-high vacuum valves, low-pressure valves, medium-pressure valves, high-pressure valves and ultra-high-pressure valves according to nominal pressure.

Low vacuum valve—105～10²Pa

Medium vacuum valve—102～10-1Pa

High vacuum valve—10-1～10-5Pa

Ultra-high vacuum valve—less than 10-5Pa

Low pressure valve—nominal pressure ≤ PN16

Medium pressure valve—PN16 <nominal pressure≤PN100

High pressure valve—PN100 <nominal pressure≤PN1000

Ultra-high pressure valve—nominal pressure>PN1000.

How are valves classified according to their nominal size (diameter)?

Valves can be divided into small diameter valves, medium diameter valves, large diameter valves and extra large diameter valves according to their nominal size.

Small diameter valve—nominal size ≤ DN40

Medium diameter valve—DN50≤ nominal size≤DN300

Large diameter valve—DN350≤nominal size≤DN1200

Extra large diameter valve—nominal size ≥DN1400

Valves can be divided into high temperature valves, medium temperature valves, normal temperature valves, low temperature valves and ultra-low temperature valves according to their working temperature.

High temperature valve—t>425℃

Medium temperature valve—120℃≤t≤425℃

Normal temperature valve - -29℃<t<120℃

Cryogenic valve—-100℃≤t≤-29℃

Ultra-low temperature valve—t<-100℃

Valves can be divided into cut-off valves, check valves, distribution valves, regulating valves, safety valves, other special valves and multi-purpose valves according to their uses and functions.

Cut-off valve - used to cut off or connect the medium in the pipeline. Such as gate valves, globe valves, ball valves, butterfly valves, diaphragm valves, plug valves, etc.

Check valve - used to prevent the backflow of media in the pipeline. Such as check valve (bottom valve).

Distribution valve - used to change the flow direction of the medium and play the role of distributing, separating and mixing the medium. Such as three-way ball valve, three-way plug valve, distribution valve, trap, etc.

Regulating valve - used to regulate the pressure and flow of the medium. Such as pressure reducing valve, regulating valve, throttle valve, balancing valve, etc.

Safety valve - used for overpressure safety protection and discharge of excess media to prevent the pressure from exceeding the rated safety value. When the pressure returns to normal, the valve will be closed again to prevent the medium from continuing to flow out. Such as various safety valves, relief valves, etc.

Other special valves - such as vent valves, slag discharge valves, sewage valves, pigging valves, etc.

Multi-purpose valves—such as stop check valves, check ball valves, filter ball valves, etc.

Valves can be divided into truncated gate-shaped, gate-shaped, plug-shaped, swing-shaped, butterfly-shaped and slide valve-shaped according to their structural characteristics.

Portal shape - the opening and closing parts (valve discs) are driven by the valve stem to move up and down along the centerline of the valve seat [Figure 1-1 (a)].

Gate shape - the opening and closing parts (gate plates) are driven by the valve stem to move up and down along the center line perpendicular to the valve seat [Figure 1-1(b)].

Plug shape - the opening and closing member (ball or cone plug) rotates around its own center line [Figure 1-1 (c)].

Swing type - the opening and closing parts (valve disc) rotate around the pin outside the valve seat [Figure 1-1 (d)].

Butterfly - the opening and closing parts (butterfly disc, butterfly plate) rotate around the fixed axis in the valve seat [Figure 1-1 (e)].

Spool valve type - the opening and closing parts slide in the direction perpendicular to the channel [Figure 1 - 1 (f)].

According to the connection method with the pipeline, valves can be divided into threaded connection valves, flange connection valves, welded connection valves, clamp connection valves, ferrule connection valves and clamp connection valves.

Threaded connection valve - The valve body has internal or external threads and is threaded to the pipe.

Flange connection valve - the valve body has a flange and is connected to the pipe flange.

Welded connection valve - the valve body has a butt welding groove or socket, and is welded to the pipe.

Clamp connection valve - the valve body has a clamp port and is connected to the pipe by a clamp

The valve is connected with a ferrule - it is connected to the pipe using a ferrule.

Clamp connection valve - a connection form that uses bolts to directly clamp the valve and the pipe flanges at both ends together.

Metal material valves—valve bodies and other parts are made of metal materials. Such as cast iron valves, carbon steel valves, stainless steel valves, alloy steel valves, copper valves, aluminum alloy valves, lead alloy valves, titanium alloy valves, Monel alloy valves, etc.

Non-metallic material valve - the valve body material is made of non-metallic material. Such as plastic valves, ceramic valves, enamel valves, fiberglass valves, etc. Metal body lined valve - The valve body is made of metal, and all the main internal surfaces in contact with the medium are lined. Such as fluorine plastic lining, rubber lining, ceramic lining, other materials lining, etc.