Pneumatic valve flow coefficient and cavitation coefficient of explanation

pneumatic valve pneumatic valve are the important parameters of the flow coefficient of the gas corrosion coefficient, the production of pneumatic valve data in advanced industrial countries generally can provide, even printed in the sample. Pneumatic valves are produced in our country basically do not have this information, because this information need to experiment to put forward, this is our country and the world's advanced level of gap is one of the important performance of pneumatic valve.

a, pneumatic valve flow coefficient

pneumatic valve flow coefficient is a measure of flow capacity of pneumatic valve flow coefficient value, the greater the instructions when fluid flows through the pneumatic valve of the pressure loss is smaller.

according to the calculation formula of the KV value

type: the KV - Flow coefficient Q - Volume flow m/h Δ P - Pneumatic valve pressure loss barP - Fluid density kg/m

2, pneumatic valve cavitation coefficient

gas corrosion coefficient of the delta value, to select when used as a control flow, choose what kind of pneumatic valve structure.

type: H - Pneumatic valve (after Export pressure mH - Atmospheric pressure and temperature of the saturated vapor pressure difference between the corresponding m Δ P - Pneumatic valve pressure difference before and after m

all kinds of pneumatic valves with the different structure, therefore, allow different cavitation coefficient of the delta. As shown. Such as calculation of cavitation coefficient is greater than the allowable cavitation coefficient, then available, cavitation will not occur. Pneumatic valve allows for cavitation coefficient is like a butterfly. Is:

as the delta >. , cavitation will not occur.

when. ＞δ＞. When slight cavitation happens.
　　
　　δ＜. When vibration is produced.
　　
　　δ＜. Continue to use, will damage the pneumatic valve and downstream piping.

the basic characteristic of the pneumatic valve and the operating characteristic curve, the pneumatic valve when cavitation occurs is invisible, but to not to come out at that point to limit operation. Through the above calculation is obvious. So produce cavitation, because the liquid in the process of accelerating flow through a tapered cross section, the partial gasification of liquid, then the bubble burst after pneumatic valve open section and its performance has three:

( Noise

( Vibration ( Serious when can cause basis and related structures damage, produce fatigue fracture

( Damage to the material ( On the pneumatic valve and piping erosion

in from the above calculation, it is not hard to see produce cavitation and pneumatic valve after pressure has great relations H, increasing H would certainly make things change, to improve methods:

a. The pneumatic valve is installed in the pipeline is relatively low.
　　
　　b. Pipe jacket after pneumatic valve orifice increase resistance.
　　
　　c. Pneumatic valve outlet opening, reservoir directly, make the space of the bubbles burst, reduce cavitation.

based on the analysis of the above several aspects, to explore, sums up main characteristics of the pneumatic valve, butterfly valve and the parameter list is easy to choose. Two important parameters used in pneumatic valve plays a pivotal role.