Because the double-seat control valve has an upper valve seat and a lower one, its unbalance force is small which makes it suitable for occasions where the pressure difference is relatively large and the request for leakage is not high. The equal-caliber double-seat control valve can also be used when the standard request for the actuator is low. However, the double-seat control valve has a messy flow path and is of small adjustable size. Also, its resistance to movement is large; The valve stem moves up and down and the stability of the spool is poor, namely, the oscillation is large.
The segment ball valve has great advantages over the straight-stroke double-seat control valve. These advantages are determined by its structure. The spool of the segment ball valve is constructed with a migraine structure. In addition to the closed orientation, the spool seat does not touch the remaining orientation which reduces wear and tear. Once the spool is opened, it will disengage the valve seat which reduces the operating torque. The unique segment notch on the spool can ensure a good regulation performance of the valve at a small opening degree which solves the problem that the straight-stroke valve has poor operating performance at a small opening degree.
The flow path of the segment ball valve is simple which is of single straight-flow type and has small movement resistance and large adjustable scale. The pressure recovery coefficient of the flow-opening valve is higher than that of the double- seat valve which is more suitable for the situation of cavitation.
The motion mode of the spool and the valve stem of the segment ball valve is rolling which is more suitable for the situation where the pressure difference is large than the linear motion valve and is 2.5 to 10 times that of the straight stroke valve.
When dealing with high temperature, the segment ball valve deals with the spool seat expanding at high temperature with a rigid and flexible connected elastic sea. Both the advantages and disadvantages of the segment ball valve and the double-seat control valve are considered when choosing high-temperature wear-resistant filler to ensure the reliability of the valve stem sealing at high temperatures.
Segment ball valve compared with single-seat control valve: Segment ball valve is receiving more and more attention in the field of industrial automatic control due to its wonderful regulation performance and cutting performance. Many single-seat control valve applications are tended to be replaced with segment ball valves.
The advantages of the V-ball valve over the single-seat control valve are:
First, the volume and weight of the segment ball valve are smaller than those of the single-seat control valve of the same diameter while its performance price ratio is higher. For users who have limited budget but want to use the control valve, it can help them save a lot of expenses . For the situation where the installation space is limited, the segment ball valve is also better.
Second, though the leakage of the single-seat control valve is relatively small, it cannot achieve zero leakage which cannot meet the requirements for the situation where the requirement for the leakage is strict. However, and the segment ball valve can achieve zero leakage which can meet the regulation performance requirements of the control valve as well as the cutting requirements of the shut-off valve.
Third, the ball of the segment ball valve has a shearing function which makes it a good choice for media containing solid particles. During the rotation process, the ball can produce a wiping effect which ensures that there will never accumulate media on the sealing surface. And in the transporting process of the papermaking plant, the segment ball valve is also the best choice.