Other types of valves

Valves are available in various shapes and sizes. In addition to "Valve Piping"Typical of Shang Han GaiValvesIn addition, it is important to note that there are other types of valves available. This page will provide a quick overview of some of the non-standard types of valves.

Plug Valves

A plug valve is a valve with a cylindrical or tapered "plug" that rotates inside the valve body to control the flow through the valve. The plug in a plug valve has one or more hollow channels that pass laterally through the plug so that the fluid can flow through the plug when the valve is open. Plug valves are simple and often economical.
When the plug is tapered, the rod/handle is usually attached to the larger diameter end of the plug. Plug valves usually do not have a cap, but the end of the plug usually has an exposed or mostly exposed handle. In this case, there is usually not much root. The stem and handle usually form a single unit, usually a simple, nearly L-shaped handle attached to the end of the plug. The other end of the plug is usually also exposed on the outside of the valve, but has a mechanism to keep the plug inside the body.
The simplest and most common general purpose plug valve is the 2-way valve, which has two positions, open to allow flow and closed (shut) to stop flow. The holes are openings in the valve body through which the fluid can enter or exit. The plug in this type of valve has a passage through it. These ports are usually at opposite ends of the body. Thus, the plug is rotated a quarter turn to change from the open position to the closed position. This makes this plug valve a quarter-turn valve. There is usually a mechanism to limit the movement of the handle to a quarter turn, but not in the case of glass plug valves.
A tapered metal (usually brass) plug valve is commonly used as a simple shut-off valve in natural gas pipelines.
The plug valve can also have more than two ports. In a 3-way plug valve, flow from one port can be directed to a second or third port. It is also possible to design the three-way plug valve to switch the flow between ports 1 and 2, 2 and 3 or 1 and 3, or possibly even to connect all three ports together. The possibilities for diverting the flow in a multi-port plug valve are similar to those in the corresponding multi-port ball valve with a rotor. Another possibility of the plug valve is to have one port on one side of the plug valve and two ports on the other side, with two diagonal and parallel fluid channels inside the plug. In this case, the plug can be rotated 180° to connect the port on one side to either of the two ports on the other side.

Needle Valves

A needle valve is a valve with a small port and a needle-like plunger with a thread. It can precisely regulate the flow rate even though it is usually only available at relatively low flow rates.
The needle valve has a relatively small orifice with a long, tapered seat, and a needle plunger at the end of the screw that fits right into the seat.
With the rotation of the screw and retraction of the plunger, flow between the seat and the plunger may occur. However, until the plunger is fully retracted, the flow is severely impeded. Since it takes many turns of the fine threaded screw to retract the plunger, the flow can be precisely regulated.
The advantage of the needle valve is the vernier effect of the ratio of the length of the needle to its diameter or the difference in diameter between the needle and the valve seat. The long stroke of the axis (control of the input) results in small and precise changes in the radial direction (affecting the final flow). Needle valves can be used in vacuum systems when very precise control of the air flow at low pressure is required.

Low Temperature Valve

Cryogenic valves are used for extreme low temperatures. Low temperature valves are usually made of all stainless steel with special elastomers to cope with low temperatures. Cryogenic valves have an extended bonnet to keep the operator away from the cold process running through the valve port. Cryogenic valves are usually ordered to certain specifications; however, they can be tested to BS6364 (British Standard for Low Temperature).

Y-shaped valve

Y-valves are designed to withstand the full range of stresses caused by operating pressure. The design also increases the flow rate through the valve compared to conventional globe and check valves.
Check piston and nozzle check valve
Non-emergency piston check valves are equipped with a counterweight or other mechanism (hydraulic) to control the closing time of the valve.
The nozzle check valve (commonly referred to as the Noz check valve) has a spring-assisted flap that moves axially with minimal displacement to open. The design provides a streamlined flow path and creates a venturi effect through the valve, thereby reducing low pressure drop. When the flow rate decreases, the flap responds immediately