What Are the Basic Functions of Valves? Types of Common Valves

The main job of a valve is to control fluid flow. In piping systems, medium covers not just liquids like water, oil, and chemical solutions. It also includes gases such as steam, compressed air, natural gas, flue gas, and even slurry with solid particles.

In real engineering work, valve roles usually fall into five main groups.

1. Connecting and Shutting Off the Medium

Many pipeline tasks need just two positions: fully open or fully closed. The medium moves through easily. When the valve closes fully, the sealing surfaces press tightly together. This stops the flow completely.

Typical shut-off valves include gate valves, ball valves, and some butterfly valves.

For example, the main water valve in home plumbing or the master shut-off valve in gas lines does exactly this job.

2. Regulating Flow and Pressure

In many industrial processes, fluid flow does not stay steady. It needs changes based on operating needs. Valves handle this task by adjusting the flow area between the valve core and seat. This controls the flow rate. It also affects downstream pressure in an indirect way.

Valves built for throttling and regulation usually need:

• Smooth opening and closing traits
• High control accuracy
• Good stability over a wide flow range

Common valves for this include globe valves, control valves, and certain butterfly valves.

3. Changing the Flow Direction of the Medium

Complex pipeline setups often require fluids to divert, mix, or redirect to match process needs. Some valves have several internal flow paths. These let operators switch the medium's direction.

The most frequent valves for this role are three-way valves and four-way valves. They allow flexible pipeline setups and cut down on extra pipe fittings.

4. Preventing Backflow of the Medium

Most pipeline systems demand flow in one set direction. Reverse flow can create serious issues, such as: Pump reverse rotation, Equipment damage

• Contamination of process media
• System pressure instability

Check valves (also called non-return valves) stop these problems. They work automatically with no manual input.

When fluid moves in the correct direction, pressure opens the valve. If reverse flow starts, the valve shuts on its own. It uses gravity, spring force, or reverse pressure.

5. Pressure Relief and Safety Protection

Pressurized systems face big risks from too much pressure. This can cause explosions, pipe bursts, or equipment failure. Safety valves install to release extra pressure automatically.

When pressure goes above a set limit:

• • The valve opens on its own
  • Excess fluid discharges
  • Pressure returns to a safe level

After pressure falls back to normal, the valve closes again. This protects system integrity.

Common safety protection valves include:

• • Safety valves
  • Pressure relief valves

Valves differ a lot in structure and design. Based on how they work and their inner build, common industrial valves usually divide into eight main types.

1. Gate Valve

Gate valves rank among the most used shut-off valves in industrial piping systems. The closing part is a gate plate. It moves up and down across the flow direction.

2. Globe Valve

Globe valves feature a disc-type closure element. It moves along the centerline of the valve seat.

Compared to gate valves, globe valves show higher flow resistance. However, they offer much better sealing and control ability.

3. Ball Valve

Ball valves contain a spherical closure element with a central bore. A 90-degree turn of the ball gives quick open or close action.

4. Butterfly Valve

Butterfly valves have a rotating disc as the closure element. The disc turns around a shaft to manage fluid flow.

5. Check Valve

Check valves stop reverse flow in pipelines automatically.

6. Safety Valve

Safety valves guard equipment. They release pressure automatically when system pressure passes safe limits.

7. Pressure Reducing Valve

Pressure reducing valves lower incoming fluid pressure. They keep downstream pressure steady despite upstream changes.