Centrifugal pumps
Operating problems in acentrifugal Pumpwhich can cause damage to the centrifugal pump can be either hydraulic or mechanical. In the first category (hydraulic), a pump may fail to deliver liquid, it may deliver an insufficient capacity or develop insufficient pressure, or it may lose its prime after starting. In the second category (mechanical), it may consume excessive power or symptoms of mechanical difficulties may develop at the seal chambers or at the bearings or vibration noise or break-age of some pump parts. For example increased wear at the running clearances must be classified as a mechanical trouble but it will result in a reduction of the net pump capacity—a hydraulic symptom—without necessarily causing a mechanical breakdown or even excessive vibration. So it is important to classify symptoms and causes separately.
Daily inspections should be made and any irregularities in the operation of a pump should be recorded and reported immediately. This applies to changes in sound of a running pump, abrupt changes in bearing temperatures and seal chamber leakage.
A check of pressure gauges and of flow meters and vibration should be made regularly during the day. If recording instruments are provided a daily check should be made to determine whether the current capacity, pressure, power consumption or vibration level indicates that further inspection is required. Trending charts should be produced to allow observation of changes as a function of time. Certain trends may allow for scheduled outages to address deterioration of specific performance values.
防止离心泵损坏的预防措施。
Centrifugal pumps must be monitored regularly, correctly and accurately according to a specific plan which is made by a specially trained personnel. The following six parameters should be regularly monitored to understand how a pump is performing:
- Suction pressure (Ps)
- Discharge pressure (Pd)
- 流（Q）
- 泵速（n）
- Pump efficiency (η)
- Power.
The advantages regular monitoring of the pumps are -
- 无需拆卸泵。
- Offers cost savings and energy savings by increasing the pump availability andreliability coefficients for pumps.
- 维护泵集的时间可能会根据预测性和计划的维护策略进行预测和计划。
- If a flow meter is installed to measure process liquid flow, then the pump monitor is able to verify the accuracy of the meter readings by calculating ‘Q’ from the empirical formula for power ‘P’.
In addition, it is very important to monitor some other conditions for centrifugal pump during normal operation such as:-
- Vibration monitoring.
- Oil level and schedule oil Analysis.
离心泵检查时间表
离心泵检查应定期进行。但是，对于不同的检查水平，这些泵检查的频率有所不同。因为在常规泵检查中，只能易于监测压力，温度，振动等因素。但是在季度检查中，还应检查轴对齐和石油水平。下面讨论了一些典型的检查时间表以及要执行的活动清单。
Routine inspections
Perform the following tasks whenever you check the pump during routine inspections:
•通过轴承框架上的视玻璃检查油的水平和状况。
•Check for unusual noise, vibration, and bearing temperatures.
•Check the pump and piping for leaks.
•Analyze the vibration.
•检查排出压力。
•Inspect the temperature.
•Check the seal chamber and stuffing box for leaks.
•Ensure that there are no leaks from the mechanical seal.
•Adjust or replace the packing in the stuffing box if you notice excessive leaking.
Three-month inspections
Perform the following tasks every three months:
•检查粉底和固定螺栓是否紧绷。
•检查机械密封是否使泵的闲置闲置，然后根据需要更换。
•至少每三个月（2000个操作小时）每三个月更换石油。
•Change the oil more often if there are adverse atmospheric or other conditions that might contaminate or break down the oil.
•检查轴对齐，并根据需要重新调整。
Annual inspections
每年一次进行以下检查：
•检查泵容量。
•Check the pump pressure.
•Check the pump power.
If the pump performance does not satisfy your process requirements, and the process requirements have not changed, then do the following:
1. Disassemble the pump
2. Inspect it.
3.更换磨损的零件。
Pump Maintenance Schedule
常规维护（可以在泵操作期间进行）
每当执行例行维护时执行以下任务：
- Clean bearing bracket from any oil if found.
- 检查排油塞。
- Lubricate the bearings.
- Inspect suction and discharge flanges for any leak.
- Inspect pump casing for any unusual damage signs.
- Inspect the seal.
- If the pump is offline check the coupling and its shims for any damage.
- 确保耦合防护罩已很好地拧紧到泵底板。
- Check that motor alignment bolts are all in place.
