Top 10 Troubles When you use Regulatory Valves
For single-core valves, once the medium is flow-open type, they’re stable. Once the medium is flow-closed type, they’re unstable. There’re two valve cores in the two-seat valve. The lower core is in flow-closed condition while the top of core is in flow-open condition. In cases like this, under small opening conditions, the flow-closed kind of valve core will easily cause oscillation of the valve. For this reason two-seat valves may be used for small opening conditions.
2. Why can’t double-sealing valves be utilized as sanitary shut-off valves?
Two-seat valve core has the benefit of balanced force double-sealing valve structure, allowing a large pressure difference. And its shortcoming is that the two sealing surfaces can not be in good contact at the same time, causing a large leakage. If it’s purposefully and mandatorily utilized in shut-off occasions, the result won’t be good, even though plenty of improvements have now been made on it. (such as double-sealing sleeve valve)
The core of straight stroke valve is vertical throttle, but the flow direction of the medium is horizontal. So there has to be a lot of twists and turns in valve cavity flow channel, Anix Valve making the flow paths of the valve very complex. Therefore, there’re plenty of blind zones that provide space for deposition of the medium, which in the future causes clogging. The throttle direction of rotary stroke valve is horizontal, the medium horizontally flows in and out, that may easily eliminate unclean medium. Meanwhile, the flow path is easy, and there’s little room for medium deposition, so rotary stroke valve includes a good anti-blocking performance.
4. Why is the stem of straight stroke regulating valve thin?
It involves a straightforward mechanical principle: the larger the sliding friction, small the rolling friction. The stem of straight stroke valve moves up and down. If the stuffing slightly pressed a little tighter, it’d wrap up the stem tightly, resulting in a large hysteresis. To this end, the valve stem was created to be thin and small and the stuffing use PTFE that has a small friction coefficient to be able to reduce the hysteresis. But the situation that derives from this is a thin valve stem is easy to bend and the stuffing includes a short service life. To resolve the situation, the best way is to utilize rotary valve stem, a regulating valve just like the rotary stroke ones. Its valve stem is 2 to 3 times thicker than that of the straight stroke valve. And it uses graphite stuffing that has a long service life. The valve stem stiffness is good, the service life of stuffing is long, the friction torque and hysteresis are instead small.
The medium of desalination water contains low concentrations of acid or alkali, which are pretty corrosive to rubber. The corrosion of rubber is exemplified by expansion, aging and low strength. Poor people effect of using rubber lined butterfly valve and diaphragm valve is actually caused by the intolerance of corrosion of rubber. Rear rubber-lined diaphragm valve is improved to function as the fluorine lined diaphragm valve that has a great tolerance of corrosion. But the lining of diaphragm of fluorine lined diaphragm valve can’t withstand the up-and-down folding and is broken, causing mechanical damage and shorter service life of the valve. Now the best way is to utilize water treatment special ball valves, which can be used for 5 to 8 years.
7. Why should shut-off valves try to use hard sealing?
Sanitary shut-off valves require the leakage to be as little as possible. The leakage of soft sealing valve is the lowest, so the shut-off effect is certainly good. But it’s not wear-resistant, not reliable. Judging from the double standard of small leakage and reliable sealing, soft sealing shut-off isn’t just like hard sealing shut-off. Take full-featured ultra-light regulating valve like, it’s sealed and piled with wear-resistant alloy for protection, highly reliable, includes a leakage rate of 10 to 7, all of which have met the requirements of shut-off valves.
8. Why can’t sleeve valves replace single-seat and double-seat valves?
Sleeve valves, which first appeared in the ’60s, were widely utilized in the ’70s worldwide. Sleeve valves account fully for a large percentage in petrochemical equipment imported through the ’80s. At that time, many people thought sleeve valves could replace single-seat and double-seat valves to end up being the second-generation products. Until now, that’s not the case. Single-seat valves, double-seat valves and sleeve valves are equally used. That’s because sleeve valves only improve the way of throttle, have better stability and maintenance than single-seat valves. But its weight, anti-blocking and leakage indicator are the same as those of single-seat and double-seat valves.
9. Why is selection more important than computation?
Compare computation with selection, selection is more important and more complicated. Computation is merely a simple formula. It’s not the formula itself, but alternatively the accuracy of given parameters that matters. Selection involves plenty of things, being fully a bit careless will result in improper selection, which not merely results in the waste of manpower, material, and money, but the consequences of good use are not good, causing numerous problems used, such as for example reliability, service life and quality, etc.