1. Structure
The main feature of the multistage pump control valve structure is that the positioning mechanism in the middle of the valve seat and the spring on the upper side of the valve disc are eliminated, and the deflector is designed on the lower side of the valve flap to minimize the mechanical loss of the medium overcurrent. And the vortex loss in the lower sac cavity of the valve flap. The piston in the cylinder is used as a driving component to drive the valve flap up and down under the pressure of the medium itself to realize the opening or closing of the valve. The piston, the opening and closing member, and the cylinder block are arranged on the valve body, and the valve body of the streamlined and wide valve cavity can not only reduce the head loss by more than 30%, but also has good cavitation resistance.
2. Operating characteristics of multi-stage centrifugal pump and functional characteristics and working principle of control valve
The centrifugal pump has the minimum shaft power at zero flow conditions, which is 30%-90% of the rated shaft power. Therefore, the starting characteristic of the centrifugal pump is zero flow start (ie, the valve is closed). After the pump has been pumped to the rated speed, the control valve opens slowly at the set speed.
Working principle: When the pump starts (pre-), the pressure water flows through the solenoid valve with delay to the upper chamber of the piston in the cylinder, while the lower chamber of the piston passes through the lower end of the cylinder to the atmosphere through the solenoid valve. At this time, the control valve is closed.
When the motor compensation starts, the pump runs normally, the solenoid valve executes the reversing command, cuts off the pressure source of the upper chamber of the piston, closes the circuit leading to the atmosphere at the lower end of the cylinder, and simultaneously injects the pressurized water into the lower chamber of the cylinder through the solenoid valve and opens the piston. The upper chamber leads to the atmosphere, the water in the upper chamber of the piston is discharged outside the valve through the solenoid valve, and the control valve is slowly opened at the set speed, which completes and satisfies the starting characteristic of the minimum power of the centrifugal pump at zero flow, and ensures the pump unit. Safe operation.
