Weak current College】 【control valve common troubleshooting methods (4).

<br> 5. control valve noise solution (8 way) <br> 1) eliminate resonance noise law <br> Only the control valve, a resonance energy superposition and 100 DB's strong noise. There's a strong performance for the vibration, noise and .vibration are weak, but the noise is very big; vibration and noise are larger. This type of noise to produce a single tone of voice, its frequency is usually 3000-7000 Hz. Obviously, eliminate resonance, noise nature disappear. Methods and examples .see 4.5 4), 5), 6). <br> 2) eliminate cavitation noise law <br> Cavitation is the main source for fluid power noise. Cavitation bubble burst when produce high-speed impact, its local produce severe turbulence, cavitation .noise. This type of noise has a wide range of frequencies, rattle, and fluid containing sand and sound similar. Eliminate and reduce cavitation is eliminate and reduce the noise of effective approaches. <br> 3) use of thick-line method <br .> Use of thick-walled tube is one of the acoustic road approach. Use the shell to enable noise increase 5 decibels, the use of thick-walled tube makes noise reduction of 0 to 20 DB. The more of the same diameter, wall thickness .of the tube diameter of the same wall thickness, the better the effect of reducing the noise. If the wall thickness of pipes, DN200 respectively 6.25, 6.75, 8, 10, 12.5, 15, 18, 20, 21.5mm, reduces noise respectively .-3.5, -2 (ie increase), 0, 3, 6, 8, 11, 13, 14.5 DB. Of course, the more thick walls of the cost. <br> <br> 6. regulating valve vibration solution (8 .way) <br> Increased stiffness method 1) <br> On the oscillation and the slight vibration, increases the stiffness to eliminate or reduce such as selection of great stiffness of the spring, use piston actuators and other approaches are possible. <br> .2) increased damping method <br> Increased vibration damping is increasing, such as friction sleeve valve plug may use the "O" ring seals, adopting the have large friction, graphite packing, etc. to eliminate or weaken the slight vibration or have a .certain effect. <br> 3) increases with the size, reduce the Guide clearance method <br> Axis plug-shaped valve general guidance dimension are smaller, all valve clearance is generally larger, 0.4 ~ lmm, which produce machinery vibration is helpful. .Therefore, in the event of minor mechanical vibration, size by increasing orientation, reducing the clearance to weaken the vibration. <br> 4) change the throttling element shapes, eliminate resonance method <br> As a result of the so-called vibration source .control occurs at high speed flow, pressure, the throttle mouth is rapidly changing, and change the throttling element shape to change the oscillator frequency, resonance is not strong, relatively easy to solve. Specific method is in vibration within the valve to open degree surface .turning 0.5 ~ 1.0mm. As a family in the vicinity of the installation of a self-operated pressure control valve, the resonance effects produced Whistler employees rest, we dropped the core surface vehicles, resonance 0.5mm squealing sounds disappear. <br> 5 .) replace the throttling element eliminate resonance method <br> Tenets of 4.5 4), just replace the throttling element. Its methods are: ① replace to change the flow characteristics, logarithmic, linear to log-linear; ② 1.check forms. If .the shaft plug shape to "V"-shaped trough valve core, the two-seater valve shaft plug into a socket type; will open window sleeve to make up the holes of the sleeve. As a fertilizer factory a DN25 two-seater valve, .the valve stem and valve connection often broken, we confirm that the vibration for resonance, the linear characteristics of the valve into logarithmically spool, the issue is resolved. As an Aviation Institute laboratory used a DN200 sleeve valve, plug produce strong rotation could not come .into use, will open the window of the sleeve to make up the holes of the sleeve, the rotation immediately disappear. <br> 6) replacement valve type to eliminate resonance. <br> Different structure of the control valve, its natural frequency natural ., replace the valve type is fundamentally eliminate resonance of the most effective way. A valve in use resonance formidable - strong vibration (severe damage to the valve), strongly rotating (even the stem is vibration and torsion), and strong noise (up to .100 DB) valve, as long as it is replaced by a single structure differences larger valves, and immediately effective, strong resonance miraculously disappeared. If the vinylon factory of new expansion project selection one DN200 sleeve valve, these three phenomena are present, DN300 pipes .with the beat, the plug rotation, 100 decibels of noise, resonance opening 20 ~ 70%, consider resonance opening large, use a two-seater valve, resonance, the commissioning of the fine. <br> 7) reduce cavitation vibration method < .br> Due to cavitation bubble burst of natural steam vibration, should reduce cavitation on the way. ① Let bubble burst resulting impact energy does not function in solid surface, especially the valve core, but rather to let the liquid absorption. Sleeve valve has this .feature, so you can use axis plug-plug into a socket type. ② to reduce cavitation of all means, such as increasing throttle resistance, increasing the pressure contraction mouth, grading or in-line pressure, etc. <br> 8) avoid .vibration source wave hammer method <br> External vibration source wave hammer vibration caused by valve, apparently control valve normally to be avoided, if the vibration, should take appropriate measures <br> <br> <br> <br>.