( 1 )泵的大启动频率不能超过12次/小时；
( 2 ) 压差不能低于设计点，也不能在系统中引起性能参数的波动。泵出口压力表值等于压差加上入口压力表值；
( 3 ) 满负荷时电流表上的读数，保证电流不超过电机铭牌上的值；
( 4 ) 泵配套的电机有可能根据买方的要求，按实际介质比重选择，在进行试运行时，应考虑电机的功率。如果实际介质比重比试运行介质的比重小，请在试运行时，严格控制阀门的开度，避免电机过载甚至烧毁。必要时必须与泵制造商联系。
The three processes of start, operation and stop of centrifugal pump are very important for the normal operation of the equipment and the whole working process.
Next, Hangzhou Zhenxing Industrial Pump Manufacturing Co., Ltd. combs the following common pump start and stop operation steps and matters needing attention during operation:
Preparation before starting the pump
1. Irrigation pump
In addition to the submerged pump, other pumps must be filled before starting (the first start of the self-priming pump) (that is, the pumped medium must be filled into the pump chamber).
2. Pump filling of reverse filling device:
Open the stop valve of the inlet pipeline, open all the exhaust pipelines, discharge the gas, slowly rotate the rotor, and close the exhaust valve when there is no bubble in the pumped medium.
3. Filling pump of suction device:
Open the stop valve of the inlet pipeline, open all the exhaust pipelines, discharge the gas, fill the pump (the suction pipe must be equipped with a bottom valve), slowly rotate the rotor, and close the exhaust valve when there is no bubble in the pumped medium.
4. Open all auxiliary systems, and require all auxiliary systems to work for at least 10 minutes. When the whole auxiliary system works stably, the next step can be carried out. Here, the auxiliary system includes lubricating oil system, seal flushing system, cooling and heat preservation system, etc.
5. Turn the equipment to check whether it can rotate flexibly:
Start the motor, judge whether the rotation direction of the pump is correct again; fix the coupling guard after confirmation.
6. Operation of dry gas sealing system:
Open the nitrogen inlet valve to charge the sealing chamber. The air source pressure of dry gas seal must be between 0.5 and 1.0MPa. Each pump shall adjust the pressure and flow of the sealing chamber according to the specific requirements.
1. Confirm that the suction valve is fully open and the discharge valve is closed or slightly open; when there is a minimum flow pipeline, the discharge valve is fully closed and the minimum flow valve is fully open.
2. Close the outlet pipeline stop valve (the minimum flow must be guaranteed);
3. Start the motor to make the pump rotor reach the running speed;
4. Slowly open the outlet valve to make the outlet pressure and flow of the pump reach the specified value. Open the outlet valve and check the motor current change to avoid motor overload. When the flow rate increases, it is also necessary to pay attention to whether the seal of the pump has abnormal leakage, whether the vibration of the pump is normal, whether the pump body and motor have abnormal sound, and whether the outlet pressure changes, etc. if the pump has abnormal leakage, abnormal vibration, abnormal noise or the outlet pressure is lower than the design value, the cause shall be found out and handled.
5. When the pump is in normal operation, check the outlet pressure, outlet flow, motor current, temperature of bearing and seal, oil level of lubricating oil, vibration, noise of pump and leakage of seal; (according to process requirements) close the valve of minimum flow bypass. Make operation records of relevant equipment.
(1) the maximum starting frequency of the pump shall not exceed 12 times / hour;
(2) the pressure difference shall not be lower than the design point or cause the fluctuation of performance parameters in the system. The pump outlet pressure gauge value is equal to the pressure difference plus the inlet pressure gauge value;
(3) the reading on the ammeter at full load to ensure that the current does not exceed the value on the motor nameplate;
(4) the matching motor of the pump may be selected according to the requirements of the buyer and the specific gravity of the actual medium, and the power of the motor shall be considered during the trial operation. If the specific gravity of the actual medium is smaller than that of the commissioning medium, please strictly control the opening of the valve during the commissioning to avoid overloading or even burning the motor. The pump manufacturer must be contacted if necessary.
1. Slowly close the discharge valve until the flow reaches the minimum flow.
2. Cut off the power supply, stop the pump and close the outlet valve.
3. When the minimum flow bypass pipeline is set, close the discharge valve when the bypass valve is fully open, and then cut off the power supply to stop the pump. The circulating water can only be stopped when the temperature of high-temperature pump drops below 80 ℃; the sealing system (flushing fluid and sealing gas) shall be stopped as the case may be 20 minutes after the pump is stopped.
4. Standby pump: the suction valve is fully open and the discharge valve is fully closed (when the minimum flow bypass pipeline is set, the bypass valve is fully open and the discharge valve is fully closed), so as to make the pump in the suction pressure state of full liquid. The cooling water of standby pump shall be put into use continuously, and the lubricating oil level shall not be lower than the specified level. Special attention should be paid to check in winter to keep the cooling water unblocked and avoid freezing.
5. The standby pump shall be turned as required.
6. (after shutdown) for the pump to be overhauled, close the nitrogen inlet valve of dry gas sealing system first after shutdown (cooling), release the pressure in the sealing chamber, and then completely discharge the liquid in the pump and cooling water in the cooling system, so that the pressure in the pump body drops to zero, the remaining materials in the pump are purged clean, all valves are closed, and contact the substation for power failure. Site treatment shall meet HSE requirements.