The sealing performance

The sealing performance of the valve refers to the ability of the sealing parts of the valve to prevent medium leakage, which is the most important technical performance index of the valve. There are three sealing parts of the valve: the contact between the opening and closing parts and the sealing surface of the seat; Fit of packing and valve stem and stuffing box; Joint of body and bonnet. The FORMER leak IS called an ENDoleaker, commonly KNOWN as a loose CLOSE, AND WILL AFFECT THE VALVE'S ABILITY TO cut OFF THE medium. For the cut-off valve class, internal leakage is not allowed. The last two leakage is called leakage, that is, the medium leakage from the valve to the valve. Leakage will cause material loss, pollution of the environment, and serious accidents. For flammable, explosive, toxic or radioactive media, leakage is not allowed, so the valve must have a reliable sealing performance.

The flow of medium

The medium flows through the valve will produce pressure loss (both before and after the valve pressure difference), that is, the valve has a certain resistance to the flow of the medium, the medium to overcome the resistance of the valve will consume a certain amount of energy. For energy conservation purposes, VALVES SHOULD BE DESIGNED and manufactured to minimize the resistance of the valve to the flow medium.

Opening and closing forces and opening and closing moments

Opening and closing force and opening and closing moment are the forces or moments that must be applied to open or close the valve. Close the valve, the need to make the open-close part and send a form a seal between the two sealing surface pressure, but also overcome between stem and packing, the valve stem and between threads of the nut, valve rod end bearing friction and other parts of the friction force, and therefore must exert closing force and close moment, in the process of opening and closing, the valve is required for opening and closing force and the open-close torque changes, Its maximum value is at the final instantaneous of closing or the initial instantaneous of opening. Valves shall be designed and manufactured to reduce closing force and closing moment.

Opening and closing speed

Opening and closing speed is expressed as the time required for the valve to complete one opening or closing action. Generally, there are no strict requirements for the opening and closing speed of the valve, but some working conditions have special requirements for the opening and closing speed, such as some requirements for rapid opening or closing, in case of accidents, some requirements for slow closing, in case of water blow, etc., which should be considered in the selection of valve type.

Action sensitivity and reliability

This refers to the sensitivity of the valve to the change of medium parameters. For throttle valve, pressure reducing valve, regulating valve used to adjust the medium parameters of the valve and safety valve, trap with specific functions of the valve, its function sensitivity and reliability is a very important technical performance index.

Life of service

It represents the durability of the valve, is an important performance index of the valve, and has great economic significance. Usually in order to ensure the sealing requirements of the opening and closing times to express, can also be expressed by the use of time.