Knowledge

Introduction to several classifications of ball valves



The ball valve works by rotating the ball to make the valve unblocked or occluded. The ball valve switch is light in weight, small in size, can be made into a large diameter, reliable in sealing, simple in structure, convenient in maintenance, and the sealing surface and the spherical surface are often closed, and is not easily eroded by the medium, and is widely used in various industries.
Ball valve series can be roughly divided into the following categories: floating ball valve, fixed ball valve, metal hard sealing ball valve, V ball valve, wafer ball valve, thermal ball valve, pipeline ball valve, track ball valve, top loading ball valve, pigging valve, high pressure forged ball valve Three-way (four-way) ball valve, internal thread ball valve, integral ball valve, low temperature ball valve, bellows ball valve, eccentric hemisphere valve, all welded ball valve, special ball valve, etc.
O-type ball valve adopts floating structure, the core is precision casting, the surface is hard chrome-plated, the valve seat is made of metal or reinforced PTFE material, the flow port is the same as the pipe diameter, the circulation capacity is great, the flow resistance is very small, close No leakage, generally used as an on-off valve, especially suitable for high viscosity, fiber-containing, granular media.
The V-type ball valve adopts a fixed structure, and a V-shaped slit is formed in the core to realize proportional adjustment, and the flow characteristics are approximately equal percentage.
Ball valves are available in a wide range of applications, and ball valves are available for:
1. The nominal diameter is from 8mm to 1200mm.
2. The nominal pressure is from vacuum to 42 MPa.
3. Working temperature is from -204 °C to 815 °C.
Especially in the petroleum, chemical, metallurgical and other departments, the use of soft-sealed ball valves in flammable and explosive media equipment and piping systems, should pay attention to fire and fire.
Usually, the two-position adjustment, strict sealing performance, mud, wear, shrinkage passage, rapid opening and closing action (1/4 turn open and close), high pressure cutoff (large differential pressure), low noise, cavitation and gasification, A ball valve is recommended for use in piping systems where there is a small amount of leakage into the atmosphere, small operating torque, and low fluid resistance.
Ball valves are also suitable for use in piping systems with light construction, low pressure cut-off (small differential pressure), corrosive media.
Ball valves are also available in low temperature (deep cold) units and piping systems.
When a regulating performance is required, a ball valve with a special structure with a V-shaped opening is required.
In petroleum, petrochemical, chemical, electric power, urban construction, metal-to-metal sealed ball valves are available for piping systems with operating temperatures above 200 °C.
In the oxygen piping system of the metallurgical industry, ball valves that have been strictly degreased are used.
When the main line in the oil pipeline and the gas pipeline is to be buried underground, a full-bore welded ball valve is required.
Ball valves are widely used in irrigation systems and are mainly used at the inlet of branch pipes. The ball valve has a simple structure, small volume, and low resistance to water flow. The disadvantage is that opening or closing is too fast, and a water hammer is generated in the pipe (the pressure will increase when the water flow velocity in the pipe suddenly changes). Therefore, it is not advisable to use a ball valve on the main pipe, which can be used for flushing on the dry pipe, the branch pipe or the end thereof, and the flushing effect is good.
1. Install the ball valve. First remove the protective cover on both sides of the flange and clean the valve.
2. Read the instructions carefully before installation according to their specifications. If no problems are found, please install them.
3. Before connecting the pipeline, the pipeline should be cleaned. The residual dust or dirt in the pipeline will damage the sealing surface and the valve ball.
4. It is not possible to start the actuator as a lifting and hoisting point during installation.
5. The ball valve should be installed vertically parallel to the pipe.
6. There should be no other foreign objects near the pipe of the ball valve to exert pressure on the pipe, and if necessary, it should be cleaned.
7. After the installation is completed, apply the torque cross-locking flange and bolt according to the specifications.
The pneumatic ball valve is composed of a ball valve with a pneumatic actuator. The pneumatic actuator is divided into a double-acting pneumatic actuator and a single-acting pneumatic actuator. The solenoid valve is controlled to realize the ball valve switching action. The pneumatic ball valve can realize intelligent control, quickly open or close the pipeline, and can effectively control and manage the pipe network.
Pneumatic ball valve features: Pneumatic ball valve 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, which is quick, stable and reliable. , applicable widely, and other advantages.
1. Fluid resistance Xiao pneumatic ball valve is one of the smallest fluid resistances in all valve classifications. Even for reduced diameter pneumatic ball valves, the fluid resistance is quite correct.
2. The thrust bearing reduces the frictional torque of the valve stem, which makes the valve stem smooth and flexible for long-term operation.
3. The sealing performance of the valve seat is good. The sealing ring made of elastic material such as PTFE is easy to seal, and the valve sealing capacity of the pneumatic ball valve increases with the increase of the medium pressure.
4. The valve stem seal is reliable. Since the valve stem is only used for the imitation rotation and does not perform the lifting movement, the packing seal of the valve stem is not easy to be broken, and the sealing capacity increases as the pressure of the medium increases.
5. Since the material such as polytetrafluoroethylene has good self-lubricating property and the friction loss with the spherical body is small, the service life of the pneumatic ball valve is long.
6. Anti-static function: a spring is arranged between the ball, the valve stem and the valve body, and the static electricity generated by the switching process can be derived.
7. The bottom-loading valve stem and the stem of the valve stem prevent the valve stem from being sprayed out. If the valve stem seal is broken due to fire, metal contact can be formed between the convex step and the valve body to ensure the valve stem is sealed.
The electric ball valve is suitable for two-way cutting and adjustment. The connection between the electric ball valve and the actuator is directly connected. The electric ball valve electric actuator has a built-in servo system. It does not need to be equipped with a servo amplifier. It can be controlled by inputting 4-20mA signal and 220VAC power. The electric ball valve has the advantages of simple connection, compact structure, small size, light weight, small resistance, stable and reliable operation. The electric ball valve actuator can be equipped with electronic electric actuators such as UNIC, PSQ, HQ, DHL, etc. or gas piston actuators such as GTX and AL according to user requirements.