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Capacity coefficient has main effect in valve use process
From;    Author:Stand originally
The capacity coefficient of valve and cavitation erosion coefficient are the important parameter of a powerful person, the valve that this produces in advanced industry country all can be offerred commonly in the data, also imprint in example even piece. The valve that our country produces basically does not have this respect data, because obtain the data of this respect to need to do experimental ability to put forward, this is one of main show of the valve difference of advanced level of our country and world. 
The capacity coefficient  of valve
The capacity coefficient of valve is the index that measures valve throughput capacity, capacity coefficient value is greater, the pressure loss when explaining the fluid has shed valve is smaller. 
The estimation that press KV calculates type
In type: KV,  of capacity coefficient 
Q,  of bulk discharge M3/h
Δ P, the  of pressure loss Bar of valve
P,  of  of fluid density Kg/m3
The  of cavitation erosion coefficient of valve
With value of δ of cavitation erosion coefficient, come make choice of uses as when controlling flow, choose what kind of valve structure type.
In type: H1, after a powerful person (exit) pressure M 
H2, the poor M  of the saturated steam pressure of atmosphere and correspondence of its temperature photograph
Δ P, the  of the M that press difference of valve around
All sorts of valve differ as a result of construction, accordingly, δ of permission cavitation erosion coefficient is different also. If plan institute is shown. If coefficient of calculative cavitation erosion is more than coefficient of concessional cavitation erosion, explain usable, won't produce cavitation erosion. Like butterfly a powerful person coefficient of concessional cavitation erosion is 2.5, criterion: 
The > that be like δ 2.5, won't produce cavitation erosion. 
When > of 2.5 > δ 1.5 when, can produce slight cavitation erosion. 
δ < 1.5 when, generation is oscillatory. 
δ < when the circumstance of 0.5 continues to use, can injure valve and downstream tubing.
The basic and characteristic curve of valve and operation character curve, when sending angry corrode to valve look not to come out, more point to do not come out to be in that operation limit is reached on the dot. Pass afore-mentioned computation criterion be clear at a glance. Produce cavitation erosion so, because the liquid is passed in process of going from place to place quickly,be one paragraph shrinks gradually when section, partial liquid aerification, the bleb of generation widens section blast to crack after a powerful person subsequently, its expression has 3: 
(1) produces noise 
(2) is oscillatory (serious when can cause foundation and the destruction that builds thing, generation fatigue fracture) 
(The 3) destruction to material (erode to body of a powerful person and conduit generation) 
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