Do you know all the "valves"?

The valve is very important! It is applied to all machinery as a flow regulating device.
Valves reduce the energy in the fluid flow, but their use is essential in operations requiring limited flow. Therefore, it is very important to have a full understanding of the structure and work of various types of valves used on ships.
Each type of valve has a specific function, including reducing/increasing flow, regulating pressure, starting/stopping flow, releasing pressure in the pipeline system, and controlling flow direction.
The valve consists of many different parts. The first is the valve body that fixes all parts of the valve together, and then the bonnet that covers the opening. The internal parts of the valve composed of valve stem, valve seat material, assembly, valve disc, valve plug and support ring are collectively referred to as valve internals. The valve disc is designed to throttle or stop the flow, and the valve seat of the valve disc is provided by the sealing ring. The valve stem helps to close the valve.
Gate Valve
This is one of the most common valve types used on board. They help control the flow of liquid through the pipe by raising or lowering, similar to the gate. It should be noted that the Gate valve can only work under the condition of no flow or full flow, so it can only have one position. It provides full-bore flow without changing direction; It is not applicable to the operation that requires the valve to be partially opened. Gate valve has simple design and function, but there are many changes, namely rising stem type and non-rising stem part.
In rising stem gate valves, the thread of the valve stem is matched with the overall thread in the valve yoke or bonnet. During operation, the steam rises above the actuator and the valve connected to the valve stem opens. In non-rising stem gate valves, the valve disc or valve disc itself has internal thread and is connected with the valve stem. The valve rod thread is matched with the valve disc, and the valve will open or close without lifting the valve rod.
To avoid any form of leakage through the space around the main shaft in the gate valve, use gland packing. In the long run, the gland packing will be damaged, so it must be replaced regularly. Gate valves are used in applications where minimum pressure loss is required, and also in applications where two-way flow is required. These valves are usually made of cast iron.
Globe Valve
This is a linear motion valve designed to start, stop or regulate flow. The valve disc of the stop valve can be completely removed from the flow passage with the flow enabled, or the flow passage with the flow closed can be completely closed. The valve has three main valve body designs, three-way (Z-type valve body), angle valve body and Y-type valve body. These valves usually have a rising stem, and larger valves adopt external thread and yoke structure. The components of the stop valve are similar to the gate valve. The valve seat of the stop valve is located in the plane parallel to or inclined to the flow line.
The stop valve is applicable to the system that needs to adjust the flow and the fuel system that needs to adjust the flow and sealing. They are also used for water supply, condenser extraction, chemical feed and extraction drainage systems. Compared with gate valve, stop valve has good closing capacity, medium to good throttling capacity and short stroke. As the valve disc is connected to the valve stem, the stop valve can be used as a stop Check Valve.
Butterfly Valve
This is a light valve on the container of fuel, fresh water, lubricating oil or chilled water system. To better understand this valve, we can imagine a butterfly moving its wings. It is a quarter turn rotary valve for stopping/starting and regulating flow. These valves are manufactured according to the principle of pipe damper. The flow control element is a disc with a diameter approximately equal to the inner diameter of the adjacent pipe rotating along the vertical/horizontal axis. When the valve disc is parallel to the pipeline, the valve is fully opened; When the disc is vertical, the valve closes.
The butterfly valve is very suitable for handling large flow of fluid at relatively low pressure, as well as mud containing a large amount of suspended solids. Compared with globe valve, plug valve, gate valve and Ball Valve, it has many advantages, the most obvious of which is the saving in weight, space and cost. The maintenance cost of these valves is also very low because there are few moving parts.
Safety valve
These valves are specially designed to relieve pressure in the pipeline. When the internal pressure increases, the spring inside the valve opens and releases the pressure. The spring can be adjusted as needed to make the valve open faster or slower. In order to prevent major damage to the equipment, the mechanical and worker safety valves release the increased pressure before the pressure reaches the limit. When the internal pressure exceeds the preset setting, it can be adjusted and adjusted to make it pop up. Once the internal pressure reaches the normal level, the safety valve closes.
Diaphragm valve
This is a two-way open/joint flow valve, which controls the fluid flow by adjusting the area where the medium enters and exits the valve, and effectively changes its speed and speed. A layer of flexible membrane is used to control the opening and closing of the valve, so it is called diaphragm valve. These are similar to pinch valves, but they use a linear compressor to push the diaphragm into contact with the valve body. The diaphragm valve provides discrete and variable pressure control, which can be operated manually and automatically. They are also clean, leak-proof, easy to maintain, safe and effective valves, which are most suitable for medium pressure and high temperature operation requiring start/stop fluid control.
Pinch valve
It is a 2/2-way valve used to close or regulate the flow of corrosive, abrasive or granular media. The pinch valve uses compressed air to open or close the valve. The valve has no restriction. When it is in the open position, it allows a series of media to pass through the hole. The valve is composed of a flexible internal rubber sleeve, which isolates the medium and prevents pollution risk. These valves are most suitable for granular products and are cost-effective, reliable and easy to use.
ball valve
This is a stop valve that controls fluid flow through a rotating ball with a hole. By rotating the valve ball about its axis for a quarter of a turn, the medium can be blocked or flow through the valve. Ball valve is characterized by long service life and reliable sealing in the whole service life, even if the valve has not been used for a long time. In some special versions, ball valves are used for control valves. Compared with other types of control valves, the accuracy of flow control is relatively limited, so this operation is not common.