Mechanical valves are devices that control the media flow and regulate the media pressure in a machine or system. Mechanical valves can be manually or automatically operated, and help smooth different system operations with the corresponding types of valves. For machine tools that involve media flow in a working process, mechanical valves are the indispensable investment manufacturers must make.
When it comes to the media that require to be controlled over flow and pressure, several kinds are available for the mechanical valves to accommodate. In other words, to achieve optimal operation efficiency, the media determine the material choice of the valve elements. These media can be gas, liquid, or solid materials, such as air, water, or slurry. The choice of valve type also has to do with the fluidity and density of materials.
The basic elements of a mechanical valve include the valve body, valve bonnet, valve stem, valve disc and seat. The body is at the base of the valve and contains the internal parts, which are categorized as the valve trim. The bonnet is attached to the opening of the body, which is at the top of base. The stem engages the upper parts and supports the position of the valve during operation. As for the disc and seat, they are the main elements that directly conduct the valve functions against the media. It is the coordination of the above elements that realizes the purpose of adopting the mechanical valves.
So, what is the purpose of using mechanical valves? As mentioned above, the valves are specialized in controlling and regulating the media flow and pressure. A common example is the water pumps. In a water pump that distributes water from a supply system to its applications, it is important to regulate the water delivery. When water comes out from the faucet, too weak or too strong water columns are not an ideal outcome of the pump functions. This should be derived from the water flow and pressure regulation, which result in the need of mechanical valves. Such examples are numerous and each explains why valves are necessary in multiple fields.
One of the functions of a mechanical valve is pressure regulation. Simply put, through the closing and opening of the valve, the media do not suddenly start or stop to flow within the system, and the purpose of pressure regulation is achieved. The above process relies on three pressure boundaries in the valve, including the valve body, valve bonnet, and valve disc.
● Valve body
The valve body encompasses not only the internal elements, but also the channel for the media to flow through. The body of the valve covers the largest contact surface against the media being controlled, so it is recognized as the most important primary pressure boundary.
● Valve bonnet
Since the valve bonnet connects the upper and lower elements through the opening of the body, the media can go upward and pass through the bonnet. Therefore, the valve bonnet serves as the second most important pressure boundary of the mechanical valve.
● Valve disc
During an operation, the valve disc sitting on the seat ring serves as the closure of the valve body, which means the disc opens or closes the valve as it moves. Followed after the valve body and bonnet, the valve disc is regarded as the third important pressure boundary.
A mechanical valve in manual operation is equipped with a hand wheel. The operator initiates or suspends the valve by turning the wheel with hands. Although the operation doesn’t affect the existing functions the valve has, the manual operation is the less efficient and relatively uncommon form nowadays.
When the mechanical valve is automatically operated, it utilizes an actuator to turn on and off the valve. The automatic operation requires additional media for motion driving, including pneumatic and hydraulic substances. With the air or fluid pressure given from these additional media, the valve can be either fully automatic or semi-automatic depending on the requirement of application.
There are numerous types of mechanical valves available for different applications. They can be divided into three essential types, including the start/stop, throttle, and non-return valves. The start/stop valves employ the basic function of the valves, which mainly enable or prohibit the media to flow in the system. The throttle valves make more space between fully opening and closing the valves, in order to properly control the media flow. As for the non-return valves, they are dedicated to regulate the direction of the media flow.
In conclusion, applying a mechanical valve should consider different factors like material, design, and operation method, etc. Only when choosing the right valve can you ensure the smooth operation of the applied machine or system.
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