Ball valve structure is divided into floating type and fixed type

Fixed ball valve

There is a groove under the valve to fix the ball valve. In the middle is the ball valve. There is a valve stem on the upper and lower sides to fix the ball to the middle. From the outside, generally, the ball valve with a disc support point under the ball valve is a fixed ball valve.

Floating ball valve

The ball floats in the middle, and there is no support point below is a floating ball valve

The maximum diameter of floating ball valve is generally DN250

The maximum diameter of the fixed ball valve can be DN1200

The biggest difference between fixed and floating ball valves lies in the fixation of the intermediate ball. The fixation damages the seal differently. The fixed type enhances the service life of the ball valve. The fixed ball valve has a longer service life than the floating ball valve. The ball of the type ball valve floats and rotates in the cavity, which will cause the seal to float and sink. When the ball valve rotates, the stress points are different. If there is no supporting point, it will damage the seal on both sides. As long as the ball valve is used, it will cause some different degrees of pressure loss. When the ball has a supporting point, it will not cause pressure loss or the pressure loss surface will be very small, so the life of the fixed ball valve is longer than that of the floating type. , It is better to use fixed ball valve in some occasions with higher switching frequency.

Ball valve sealing

Ball valves include V-shaped ball valves, eccentric half ball valves, PVC ball valves, etc.

These are different valves specified according to different occasions

V type ball valve

The flow passage of the V-shaped ball valve is a ball valve with a cut V port, which is a fixed ball valve

Scope of application: The V port has been specially processed. It is a V-shaped incision. Like a knife, its function is to cut some fibers. For some solid particles, it will be directly crushed. The ball processing method is also different. Especially some factories have some sewage or some harder granular media, like this kind of V-shaped ball valve is more often used

Eccentric half ball valve

The eccentric hemispherical valve is similar to the V-shaped ball valve. The valve core is only half, and it is also a fixed ball valve. It is mainly used for solid particles. All solid particle ball valves use eccentric hemispherical valves. Many cement plants also use this.

Both the V-shaped ball valve and the eccentric semi-ball valve are unidirectional and can only flow in one direction, not bidirectional flow, because its ball is sealed on one side, and the seal will not be tight when it is punched by the reverse side, but only flows in one direction. The sealing will be strict when pressure is applied.

PVC ball valve

The seals of PVC valves are only EPDM (ethylene propylene diene monomer), FPM (fluorine rubber)

Hard seal ball valve

Hard seal has a special feature

There is a spring behind the hard-seal valve seat, because if the hard-seal valve seat and the ball are directly connected together, it will not rotate. When the spring is connected behind the valve seat, the ball will have flexibility during rotation, because the hard seal The problem to be solved is that the ball can function normally, but the ball will be frequently rubbed by the medium. If some particles are stuck in the valve seat seal, it cannot be used. Therefore, it is a little stretchable and depends on the hardness of the ball to stretch. If it is a soft seal, if the particles are stuck in the seal, the valve will be directly damaged when it is closed. The hard seal is the same as the V-shaped ball valve before leaving the factory with surfacing S60. The seal and the ball are hardened, so they are generally hard things. It won’t break if you scrape it a little

PPL seal

The seal also has a PPL material, its name is enhanced PTFE, the raw material is polytetrafluoroethylene, but some graphite is added to turn it into high temperature resistance, the top temperature can reach 300 ° (not long-term resistance to 300 ° High temperature), the normal temperature is 250°. If you need a long time of 300°, you should choose a hard seal ball valve. The conventional high temperature resistance of the hard seal can reach 450°, and the top temperature can reach 500°.