Special purpose valves to prevent piping problems

1. Three-way valve (directional control valve)

Three-way valves, which have three piping ports, are also called directional control valves and are used to switch flow paths or merge or split two flow paths.

The structure is based on a ball-type valve with a through hole, and two types, L port and T port, are used depending on the application.

■ ①．L port: For switching flow paths

There is an L-shaped flow path inside the ball valve, and the flow path can be switched by rotating the valve 90 degrees at a time. Because there is only one flow path, there is no function to merge or split two flow paths, or to flow in a straight line.

■ ②．T-port: Flow path switching, branching, merging, etc.

This valve creates four different flow patterns by rotating a ball valve with a T-shaped flow path by 90 degrees.

It can be used in a variety of ways, such as splitting one flow path into two, merging two flow paths, switching flow paths, or flowing in a straight direction.

2. Check valves (non-return valves, check valves)

Check valves, also known as non-return valves, are used to prevent the backflow of fluids.

It is also effective in preventing backflow on the pump discharge side, preventing return water hammer at the rising part of the liquid piping, and preventing the mixing of different fluids, and plays a major role in preventing piping problems.

Check valves are broadly divided into five types depending on their structure and purpose of use.

■ ①．Swing type

Structure: hinged opening and closing
Purpose: Prevents backflow to the pump
Characteristics: Although pressure loss is small, durability is low, so it is not suitable for piping with high flow rates or piping that is frequently opened and closed. It is used in piping where there is no risk of water hammer, such as with low head and pressure.

■ ②．Wafer type (wing type)

Structure: Two semicircular valve bodies are opened by hinges and closed by a coil spring
Purpose: Prevent water hammer
Features: Compact and can be installed in limited spaces. It helps prevent water hammer by quickly closing the valve before backflow occurs after the pump stops. However, it is vulnerable to drift and cavitation and has low durability.

■ ③．Disc type

Structure: A disc-shaped valve body is quickly closed by the force of a spring
Purpose: Prevent water hammer
Features: When the pump stops, the valve closes suddenly to prevent water hammer caused by backflow. The valve remains in the flow path, causing large pressure loss.

■ ④．Ball type

Structure: A rubber spherical valve opens and closes due to the backflow of fluid and its own weight.
Purpose: Control of fluid flow through pipes
Features: The valve body is not fixed, so it can be used with fluids that may contain foreign matter. Maintenance is easy and it has excellent durability, but it is not suitable for preventing backflow or water hammer.

■ ⑤．Lift type

Structure: The valve moves vertically inside the S-shaped valve and opens and closes under its own weight.
Purpose: Prevents backflow of fluid
Characteristics: Highly durable, but the flow path is narrow and pressure loss is large. It must be installed horizontally and cannot be used on vertical piping, so there are limitations on where it can be used.

3. Foot valve

Foot valves, which prevent backflow, are installed at the suction port of a pump. Their basic structure is similar to that of a check valve, but they have a wire screen or mesh at the suction port to prevent foreign objects from being sucked in.

When installing a foot valve, pay attention to the following points:

• - After confirming that it is working properly, install it in the correct direction.
• - Install in a location that takes maintenance into consideration.
• - To prevent air inflow, use a flange connection that is less likely to leak.

4. Air release valve (air vent)

Air vent valves are installed at high positions in piping where air tends to accumulate, creating an escape route for the air.They are installed on the discharge side of pump piping, the top of airtight containers, and the very top of torii piping, and are used to prevent air accumulation and entrapment.

The float inside the valve moves up and down according to the amount of water, opening and closing the gap between the left and right valve bodies, automatically removing air.

5. Relief valve (relief valve, safety)

A relief valve is a valve that automatically releases pressure when excessive pressure occurs in the piping due to clogging by foreign objects or closing of the valve.

By releasing fluid that has no way to escape, it disperses pressure and minimizes damage to equipment.

Relief valves have a set pressure at which they open, so select the pressure that suits the equipment you are using.

6. Pressure reducing valve (pressure reducing valve, regulator)

Pressure reducing valves reduce high liquid discharge pressure and adjust the pressure to a stable state. Their role is to suppress equipment damage, noise, and vibration caused by unstable pressure.

It is often used to reduce the pressure of gases such as gas cylinders, but it is also used to transport high-pressure circulating water to equipment with pressure or flow rate restrictions.