Pneumatic control valve pressure difference before and after choose the actuator spring range and air pressure < / div >

control pneumatic valve pressure difference before and after choose the actuator spring range and air pressure
control main evidence for the selection of pneumatic valve actuator system provided by the professional 'maximum working pressure differential, control of pneumatic valve actuator output force must be greater than the pressure, the maximum working pressure difference.
as the insurance period, suggest to control the maximum pressure of the pneumatic valve before the maximum differential pressure air pressure is to select the spring range and reasonable ( Control of positive pressure pneumatic valve later) 。 With pneumatic valve pneumatic control valve in normal working conditions before and after the calculated pressure difference as to allow the differential pressure often small, the reason may have the following:
1. When abnormal work of pneumatic valve opening may be small, the pneumatic valve before the pressure rise greatly, and maximum operating differential pressure refers to the meaning of pneumatic control valve is closed when possible differential pressure value, and in this case, the fluid conveying equipment ( Such as water pump, blower, air compressor) The export will reach the highest pressure of the equipment operation, its value is equal to the rated discharge pressure of the fluid conveying equipment.
2. When abnormal work after pneumatic valve pressure vessel pressure vessel pressure may be less than in the normal pressure value of the work. It is these two factors make when you don't work properly control before and after pneumatic valve differential pressure is much greater than normal control before and after pneumatic valve differential pressure at work, that there is no leakage of pneumatic valve in normal work in leak when you don't work properly.
in industrial boiler feed water system, for example, 35 t/h boiler feed pump pressure rating is usually 6. 0 mpa, bubble pressure is 3. Pressure is normal before 8 mpa, pneumatic control valve of 4. 0 mpa, pneumatic valve pneumatic control valve in normal working conditions the pressure difference before and after is about 0. 2 mpa, if take this value as to allow the differential, almost any a pneumatic valve can meet the requirements. But when YongQiLiang suddenly to reduce, control pneumatic valve opening will also reduce, pneumatic valve before the pressure gradually increased, until reach the feed water pump pressure rating. The pneumatic control valve before and after the pressure difference of 2. 2 mpa, general single-seat pneumatic control valve under this pressure differential is difficult to ensure no leakage.