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The most common ten major problems of the valves?

2015/7/15      view:
The most common ten major problems of the valves?
Valve the most common ten major problems
1 why cut off the valve should be selected as hard as possible seal?
Cut off the valve to the lower the better, soft sealing valve leakage is the lowest, cut off the effect is good, but not wear resistance, reliability. From the leakage of small, sealed and reliable double standards, the soft seal cut off as hard as hard seal. Such as full-featured ultra light control valve, sealed and the heap has a wear-resistant alloy protection, high reliability, leakage rate of 10-7, has been able to meet the requirements of the cut off valve.
2 why the double seal valve can not be used as a cut-off valve?
The advantages of the two seat valve spool is equilibrium structure, allowing large differential pressure, and it highlights the shortcomings of is two sealing surface can not be at the same time, good contact, causing a large leak. If it artificially and mandatory for cutting off the occasion, the effect is not good, even for it made a lot of improvements (such as double seal sleeve valve), is not desirable.
3 why is a small two seater valve opening is easy oscillation work?
For single core, when the medium is open type, the valve stability is good; when the medium is the flow of closed type, the valve stability is poor. There are two spool valve seat, the valve in the flow of closed, the valve is open flow, so that in a small opening in the work flow of closed type valve core is easy to cause the valve vibration, this is a two seat valve can not be for the work of a small opening reason.
4 what straight stroke control valve to prevent poor performance, the angle of the valve to prevent the performance of good?
Straight trip valve spool is vertical throttle, while the medium is the level of flow into the outflow, the valve chamber flow is bound to turn down, so that the valve flow path has become quite complex (shape, such as inverted "S" type). So, there are many dead, provides space, if things go on like this as the medium of precipitation, causing blockage. The direction of travel throttle valve angle is the horizontal direction, the level of flows into the medium, the level of outflow, easy to medium is not clean away, a simple flow path at the same time, precipitation medium space is little, so the angular travel valve anti blocking performance.
5 why straight trip valve stem is more thin?
Straight stroke control valve it involves a simple mechanical principle: sliding friction, rolling friction small. Straight trip valve stem up and down movement, the filler slightly pressed a little, it will be a very tight valve stem, resulting in a larger return difference. Therefore, valve stem is designed to be very small, small commonly used fillers and friction coefficient of PTFE packing, in order to reduce the return difference, but which sent is small stem, is easily bent, a shorter life packing. To solve this problem, the best way is with the brigade turn valve stem, angle stroke type valve, the valve stem straight valve stem stroke rough than 2 ~ 3 times, and use long life of the graphite packing, valve stem stiffness good, long service life of the filler, the friction torque but small, small hysteresis.
6 why the angle of the valve to cut off the pressure?
Angle of the valve to cut off the pressure of the valve is larger, because the media in the spool or valve plate on the resultant force on the rotation axis of the torque is very small, so it can withstand greater pressure difference.
7 Why replace the single sleeve valve, the valve seat has not have got one's wish?
60 years came the sleeve valve, widely used at home and abroad in the 1970s, the sleeve valve in the 1980s, the introduction of the petrochemical plant accounted for a larger proportion of that time, a lot of people think, sleeve valve can replace the single, double seat valve, to become the second generation product. Until now, is not the case, single seat valve, double seat valves, sleeve valves have been the same use. This is because only improved the sleeve valve throttle form, stability, and safeguard the single seat valve, but it's weight, anti blockage and leakage indicator with single, double seat valve is the same, how can it replace the single, double seat valves? So, they can only be used together.
8 why do the salt water medium using lining plastic butterfly valve, lined diaphragm valve service life is short?
The salt water medium containing low concentrations of acid or base, they have a greater corrosive to rubber. The corrosion performance of rubber is expansion, aging, low intensity, with the rubber lining of the butterfly valve, diaphragm valve using the effect is poor, the essence is that the rubber is not resistant to corrosion. After the rubber lined diaphragm valve to improve the corrosion resistance of good lining fluorine diaphragm valve, but the diaphragm valve diaphragm and can not be folded up and down, resulting in mechanical damage, the valve life becomes shorter. Now the best way is to use a special ball valve, which can be used to 5 ~ 8 years.
9 Why in the pneumatic valve in the piston actuator use will be more and more?
For the pneumatic valve, the piston executing mechanism can take full advantage of supply pressure, the executing agency of the size smaller than the diaphragm, greater thrust, piston O-ring and reliable than film, so its use will more and more.
10 Why is it more important to say that selection is more important?
In comparison with the calculation and selection, the selection is much more important and complex. Because the calculation is a simple formula, it is not in the formula of accuracy, but in the given process parameters are accurate. Selection related to the contents of the large, slightly careless, would lead to selection of properly, not only result in the waste of manpower, material and financial resources, and the use effect is not ideal, the use of bringing a number of issues, such as reliability, life, running quality. The company mainly produces processing water control valve, soft seal gate valve, Y filter and other products. Quality assurance, hope that the new and old customers to buy a lot of.