ball valve characteristic
Knowledge of ball valves
1; wear-resisting; Since the valve core of the hard sealed ball valve is alloy steel spray welding and the sealing ring is alloy steel surfacing, the hard sealed ball valve will not cause too much wear when opening and closing. (its hardness coefficient is 65-70):
II; Good sealing performance; Since the seal of hard seal ball valve is manually ground, it can not be used until the valve core and seal ring are completely matched. So its sealing performance is reliable.
III; Light switch; Since the bottom of the sealing ring of the hard sealed ball valve is tightly held with the valve core by the spring, the switch is very light when the external force exceeds the preload of the spring.
IV; Long service life: it has been widely used in petroleum, chemical industry, power generation, paper making, atomic energy, rocket and other departments, as well as people’s daily life.
The pneumatic ball valve is compact in structure, reliable in sealing, simple in structure and convenient in maintenance. The sealing surface and spherical surface are always closed, and are not easily eroded by the medium. It is easy to operate and maintain. It is suitable for general working media such as water, solvent, acid and natural gas. It is mainly used to cut off or connect the medium in the pipeline, and can also be used for fluid regulation and control. Compared with other valve types, the pneumatic ball valve has angular stroke output torque, quick opening Stable and reliable, widely applicable, and other advantages.
- The thrust bearing reduces the friction torque of the valve stem, which can make the valve stem operate smoothly and flexibly for a long time.
- Anti static function: a spring is set between the ball, the valve stem and the valve body to export the static electricity generated during the switching process.
- Because PTFE and other materials have good self-lubricating property and small friction loss with the ball, the service life of the pneumatic ball valve is long.
- Small fluid resistance: pneumatic ball valve is one of the small fluid resistance Zui in all valve classifications. Even the reduced diameter pneumatic ball valve, its fluid resistance is quite small.
- Reliable sealing of the valve stem: since the valve stem only rotates without lifting, the packing seal of the valve stem is not easy to be damaged, and the sealing capacity increases with the increase of the pressure of the medium.
- Good sealing performance of the valve seat: the sealing ring made of elastic materials such as polytetrafluoroethylene is easy to seal, and the sealing capacity of the pneumatic ball valve increases with the increase of the medium pressure.
ball valve advantage
- The fluid resistance is small, and the full-diameter ball valve basically has no flow resistance.
- Simple structure, small volume and light weight.
- Tight and reliable. It has two sealing surfaces, and the sealing surface materials of the ball valve are widely used in various plastics, with good sealing performance and complete sealing. It has also been widely used in vacuum systems
- Easy operation, quick opening and closing,
High performance ball valve
It only needs to rotate 90 ° from full open to full close to facilitate remote control.
- The maintenance is convenient, the ball valve structure is simple, the sealing ring is generally movable, and the disassembly and replacement are relatively convenient.
- When the valve is fully opened or fully closed, the sealing surface of the ball and the valve seat is isolated from the medium. When the medium passes through, the sealing surface of the valve will not be eroded.
- It has a wide range of applications, ranging from a few millimeters to a few meters in diameter, and can be applied from high vacuum to high pressure.
- Since the ball valve has wiping property during opening and closing, it can be used in the medium with suspended solid particles.
High processing accuracy, high cost, and difficult to use in high temperature. If there are impurities in the pipeline, it is easy to be blocked by impurities, resulting in the valve cannot be opened.
- Nominal pressure or pressure class: pn1.0-32.0mpa, ANSI class 150-900, jis10-20k;
- Nominal diameter or diameter: dn6 ~ 900, NPs 1 / 4 ~ 36;
- Connection method: flange, butt welding, thread, socket welding, etc;
- Applicable temperature: – 196 ℃ ~ 540 ℃;
- Driving mode: manual, worm gear and worm drive, pneumatic, electric, hydraulic, pneumatic hydraulic linkage, electro-hydraulic linkage;
- Valve body materials: WCB, zg1cr18ni9ti, zg1cr18ni12mo2ti, CF8 (304), CF3 (304L), CF8M (316), cf3m (316L) and Ti. Different materials can be used for water, steam, oil, nitric acid, acetic acid, oxidizing medium, urea and other media.
Ball valve Advantages and disadvantages
Advantages: ① it has the lowest flow resistance (actually 0); ② It can be reliably applied to corrosive media and low boiling point liquids because it will not get stuck during operation (when there is no lubricant); ③ Complete sealing can be achieved in a large pressure and temperature range; ④ It can realize rapid opening and closing, and the opening and closing time of some structures is only 0.05 ~ 0.1s to ensure that it can be used in the automation system of the test bench. When the valve is opened and closed quickly, the operation has no impact. ⑤ The spherical closure can be automatically positioned at the boundary position; ⑥ The working medium is sealed reliably on both sides; ⑦ When the valve is fully opened and fully closed, the sealing surface of the ball and the valve seat is isolated from the medium, so the medium passing through the valve at high speed will not cause erosion of the sealing surface; ⑧ With compact structure and light weight, it can be considered as the reasonable valve structure of Zui for low temperature medium system; ⑨ The valve body is symmetrical, especially the welded valve body structure, which can well withstand the stress from the pipeline; ⑩ The closing member can withstand the high pressure difference during closing. (11) the ball valve with all welded valve body can be directly buried underground, so that the valve internals are not corroded. The service life of Zui is up to 30 years. It is a valve for oil and natural gas pipelines.
Ball vlave Disadvantages
① because the main valve seat sealing ring material of ball valve Zui is polytetrafluoroethylene, it is inert to almost all chemical substances, and has the comprehensive characteristics of small friction coefficient, stable performance, not easy to aging, wide temperature application range and excellent sealing performance. However, the physical characteristics of polytetrafluoroethylene, including high expansion coefficient, sensitivity to cold flow and poor thermal conductivity, require that the design of valve seat seal must be based on these characteristics. Therefore, when the sealing material becomes hard, the reliability of the seal is damaged. Moreover, the temperature resistance grade of polytetrafluoroethylene is low, and it can only be used under the condition of less than 180 ℃. Beyond this temperature, the sealing material will age. In the case of long-term use, it is generally not used at 120 ℃. ② Its regulating performance is worse than that of the stop valve, especially the pneumatic valve (or electric valve).