Move those who control valve to leave degree, achieve medium discharge, pressure and fluid thereby adjust. Control valve divides dynamoelectric control valve, pneumatic control valve and fluid to move control valve to wait.

Control valve is mixed by actuator of dynamoelectric actuator or pneumatic two parts comprise control valve. Adjust and normally cent is direct sheet type and direct two-seater type two kinds, latter has throughput capacity big, lopsided the characteristic that does Xiaohe to operate stability, so normally special apply to large flow, high pressure to fall with the circumstance with little leak.

Throughput capacity Cv is one of main parameter that choose control valve, the definition of the throughput capacity of control valve is: When control valve a standard-sized sheet, two end approach valve difference is 0.1MPa, when fluid density is 1g/cm3, shed the discharge number of diameter control valve hourly, call throughput capacity, also weigh capacity coefficient, express with Cv, the unit is T/h, liquid Cv value presses type is calculated.

According to throughput capacity Cv value size checks a watch, the nominal of OK and certain control valve connects diameter DN.

The discharge of control valve is characteristic, it is in a powerful person two end press difference to maintain constant condition to fall, the opposite discharge of control valve of medium shedding classics leaves with it degree between relation. The discharge character of control valve has linear character, wait for per cent character and parabola character 3 kinds. The meaning of 3 kinds of character that pour an amount is as follows:

(1) wait for per cent character (logarithm)

The opposite journey that waits for per cent character and opposite discharge do not become linear concern, the discharge that changes the change of the discharge that causes and this a little bit in the journey of the each unit on the dot of the journey becomes direct ratio, shedding the percentage that measures change is equal. So its advantage is discharge hour, discharge change is little, when flow is large, criterion discharge change is big, be in namely differ to spend on, have identical adjustment precision.

(2) linear character (linear)

The opposite journey of linear character and opposite discharge become linear concern. The discharge change that the metabolic place of unit journey causes is changeless. When flow is large, change of discharge relative value is little, discharge hour, criterion change of discharge relative value is big.

(3) parabola is characteristic

Discharge changes into scale by 2 of the journey, have roughly linear and the intermediate character that waits for per cent character.

Can see from 3 kinds of afore-mentioned characteristic analysises, adjust with respect to its tell on function, it is in order to wait for per cent character best, its adjust stable, adjust performance is good. And the adjustment that parabola character compares linear character again performance is good, can differ according to using the requirement of the circumstance, choose among them a kind of any discharge are characteristic.
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