[Weekly Topic] What to Check When Water Pumps Are in Operation (2011.05.23-29)

⑴ Check whether the pump is operating properly, whether the pressure and current are stable and normal, and whether there is excessive vibration or noise. ⑵Check the temperature of the motor bearings, inspect the pipelines, valves, and machine seal packing for any leaks, and smell for any burnt odor during the operation of the pump. ⑶ Check the oil level and quality, as well as the operation of the cooling water system. ⑷Status of pump cranking for standby pumps ⑸ Check the cleanliness in the pump room, as well as the fire-fighting equipment, gutters, and doors and windows.

During operation, the water pump should be inspected for the following: 1. The operating conditions of the pump include pressure, whether there is leakage at the pump’s packing, whether there are any abnormal noises during operation, and whether there is vibration in the inlet and outlet pipes of the pump. 2. The operating conditions of the pump motor include: motor current, motor temperature, and whether there are any noises during operation.

While the water pump is in operation, check the following aspects: Visual inspection: 1. Oil level: For rolling bearings without oil rings, the oil level should be above the center of the balls； In bearings with oil rings, the oil level should be at a depth equal to one-fifth of the diameter of the oil ring. To monitor the oil level, a dipstick or oil gauge is installed on the bearing. 2. Oil temperature: Do not exceed 60. 3. Oil quality: It must not allow water or impurities to enter, and it must not emulsify or turn black. 4. The pointer of the vacuum gauge should not swing excessively; excessive swinging may indicate vaporization at the inlet. Additionally, the vacuum gauge reading should not be too high; a high reading may indicate that the inlet valve is blocked or stuck, or that the inlet valve flap has fallen off, as well as a decrease in the water level in the suction tank. 5. If the pressure gauge reading is too low, it may be due to poor performance of the pump’s internal components or severe wear of the sealing rings. 6. Water or medium traces: The presence of water or medium traces in the surrounding area indicates a leak. 7. Is the cooling water flowing smoothly? Listen: Are there any abnormal noises? Especially with rolling bearings, abnormal sounds usually occur when they are damaged. Pump body vibration: Abnormal vibration sound from the pump body (visible to the eye as well), possibly due to cavitation. Smell: Medium odor – The presence of an odor from the medium indicates a leak. Burnt smell: The presence of a burnt smell indicates that there is an issue with the motor.

When the water pump is in operation, it is important to check the following aspects: 1. Whether the bearings are functioning properly. 1. Oil temperature: Do not exceed 60. 2. Oil level: For rolling bearings without oil rings, the oil level should be no lower than the center of the balls ； In bearings with oil rings, the oil level should be at a depth equal to one-fifth of the diameter of the oil ring. To monitor the oil level, a dipstick or oil gauge is installed on the bearing. 3. Oil quality: It must not allow water or impurities to enter, and it must not emulsify or turn black. 4. Any abnormal noises: Especially with rolling bearings, abnormal sounds usually occur when they are damaged. II. Are the readings of the vacuum gauge, pressure gauge, and ammeter normal? 1. The pointer of the vacuum gauge should not swing too much; excessive swinging may indicate vaporization at the inlet. Additionally, the vacuum gauge reading should not be too high; a high reading may indicate that the inlet valve is blocked or stuck, or that the inlet valve flap has fallen off, as well as a decrease in the water level in the suction tank. 2. A low pressure gauge reading may be due to faulty internal components of the pump, severe wear of the sealing rings, etc.

This post was last edited by hcb081995 on 2011-5-23 09:15. It is necessary to regularly monitor the vibration levels and operation status of the pump set; if any abnormalities are detected, the causes should be identified promptly and addressed. b. Regularly check the tightness of the packing gland; if too much water leaks from the gland or no water leaks at all, adjust its tightness. When the packing is worn out, replace it with new packing promptly. Check the lubrication of the motor bearings; the oil level should be normal. If the oil is found to be degraded, it should be replaced with fresh oil, and the temperature of the bearing shells should not exceed 70°C. It is necessary to regularly monitor the motor current and the temperature of the core windings; the current should not exceed the specified value nor should it fluctuate, and the temperature of the core windings should also not exceed the specified value. Regularly check that the pump outlet pressure and the lubrication water pressure for the rubber bearings are within the normal range. Regularly check the water level in the pump suction tank as well as the inlet filter; the water level should be normal, and the filter should remain clean to prevent blockages.

What is checked during the operation of a water pump? Answer: 1. Regularly monitor and record the readings on the pressure gauges at the pump’s inlet and outlet, as well as those on the motor’s current and voltage meters and the bearing temperature gauge. If any abnormal readings are detected, the cause should be analyzed and appropriate action taken promptly. 2. Regularly use a stethoscope to listen to the sounds inside the pump (the main areas to listen to are the bearings, stuffing boxes, gland, various pump chambers, and sealing points). Pay attention to any signs of friction or impact noises; if there are significant changes in the sounds or unusual noises are detected, the pump should be stopped immediately for inspection. 3. Regularly check the lubrication condition of the pump. 4. The temperature rise of the bearings (i.e., the difference between the bearing temperature and the ambient temperature) should generally not exceed 30–40°C; however, the maximum bearing temperature must not exceed 70°C, otherwise the machine should be stopped for inspection. 5. Check whether the dripping at the packing seal of the water pump is normal; generally, the leakage should not form a stream, with 30 to 60 drops per minute being an appropriate amount. 6. In the case of large water pumps with circulating oil lubrication, it is also necessary to frequently check whether the oil supply equipment (oil pumps, oil tanks, oil coolers, filters, etc.) is functioning properly, and whether the oil return to the bearings is unobstructed. 7. When the bearing is cooled by cooling water, it is also necessary to pay attention to whether the flow of the cooling water is normal. 8 The bearing vibration of pumps in operation is also a very important parameter for operational monitoring. For large-capacity water pumps, the vibration values in the vertical, horizontal, and axial directions should be measured.

This post was last edited by hcb081995 on 2011-5-23 09:15. I. Is the bearing working properly? 1. Oil temperature: It should not exceed 60°C. 2. Oil level: For rolling bearings without oil rings, the oil level should be no lower than the center of the balls ； In bearings with oil rings, the oil level should be at a depth equal to one-fifth of the diameter of the oil ring. To monitor the oil level, a dipstick or oil gauge is installed on the bearing. 3. Oil quality: It must not allow water or impurities to enter, and it must not emulsify or turn black. 4. Are there any abnormal noises? In particular, abnormal sounds usually occur when rolling bearings are damaged. II. Are the readings of the vacuum gauge, pressure gauge, and ammeter normal? 1. The pointer of the vacuum gauge should not swing excessively; excessive swinging may indicate vaporization at the inlet. Additionally, the vacuum gauge reading should not be too high; a high reading may indicate that the inlet valve is blocked or stuck, or that the inlet valve flap has fallen off, or that the water level in the suction tank has dropped. 2. If the pressure gauge reading is too low, it may be due to faulty operation of the pump’s internal components or severe wear of the sealing rings. Additionally, when the system’s water demand is high, the pump outlet pressure also decreases. 3. An excessively high ammeter reading may be caused by a large water supply volume or friction inside the pump. If the ammeter reading is too low, it indicates that the pump has sunk underwater or that the external system does not require such a large amount of water. III. Whether the pump body vibrates: The vibration amplitude of a water pump generally should not exceed 0.08 millimeters. (Special requirements for pumps are to be specified separately.) The reasons for vibration include: 1. The centers of the water pump and the motor are not aligned. 2. The foundation screws of the pump body or motor are loose, or the foundation is not solid. 3. The bearing cover is not tightened enough. This caused the bearing shells to vibrate inside the body. 4. Unbalanced rotor mass. 5. Volute pumps, especially those with high head, also experience varying degrees of vibration at low flow rates, as radial forces act on the rotor at such times. When the outlet valve is opened to a certain extent, the vibration disappears. IV. Is the sealing working properly? 1. The packing should allow a slight amount of water to drip; it should not be too tight, otherwise heat and smoke will be generated. But if it is too loose, it will cause significant leakage, and oil can easily get into the bearings, leading to oil emulsification. The packing should be replaced regularly, as it loses its ability to provide shaft sealing when it hardens. Prolonged soaking can cause the filler tank to deteriorate. 2. The end-face seal must be filled with liquid before operation to prevent dry grinding; for equipment that has not been in use for a long time, it is best to manually rotate the shaft. For media that tend to crystallize or are in granular form, and when the medium temperature is ≥100, the most effective approach is to implement appropriate flushing, filtering, cooling measures, as well as auxiliary sealing devices.

1. Regularly monitor changes in voltage and current; when the current exceeds the rated value or the voltage exceeds the rated value by ±5%, the pump should be stopped for inspection and corrective action to be taken. 2. Check whether the bearing temperatures of each component are within limits; the temperature of sliding bearings should not exceed 65°C, while that of rolling bearings should not exceed 75°C. 3. Pay attention to the sounds and vibrations in various parts, especially whether there is any noise caused by vapor swirls. 4. Check the condition of the packing seal, as well as whether the temperature of the packing box and the balancing mechanism are normal; the packing should leak 10–20 drops of water per minute. 5. Regularly pay attention to the changes in the pressure gauge and vacuum gauge.

When the water pump is in operation, it is important to check the following aspects: 1. Whether the bearings are functioning properly. 1. Oil temperature: Do not exceed 60. 2. Oil level: For rolling bearings without oil rings, the oil level should be no lower than the center of the balls ； In bearings with oil rings, the oil level should be at a depth equal to one-fifth of the diameter of the oil ring. To monitor the oil level, a dipstick or oil gauge is installed on the bearing. 3. Oil quality: It must not allow water or impurities to enter, and it must not emulsify or turn black. 4. Any abnormal noises: Especially with rolling bearings, abnormal sounds usually occur when they are damaged. II. Are the readings of the vacuum gauge, pressure gauge, and ammeter normal? 1. The pointer of the vacuum gauge should not swing too much; excessive swinging may indicate vaporization at the inlet. Additionally, the vacuum gauge reading should not be too high; a high reading may indicate that the inlet valve is blocked or stuck, or that the inlet valve flap has fallen off, as well as a decrease in the water level in the suction tank. 2. A low pressure gauge reading may be due to faulty internal components of the pump, severe wear of the sealing rings, etc.

I. Is the bearing working properly? 1. Oil temperature: Do not exceed 60. 2. Oil level: For rolling bearings without oil rings, the oil level should be no lower than the center of the balls ； In bearings with oil rings, the oil level should be at a depth equal to one-fifth of the diameter of the oil ring. To monitor the oil level, a dipstick or oil gauge is installed on the bearing. 3. Oil quality: It must not allow water or impurities to enter, and it must not emulsify or turn black. 4. Any abnormal noises: Especially with rolling bearings, abnormal sounds usually occur when they are damaged. II. Are the readings of the vacuum gauge, pressure gauge, and ammeter normal? 1. The pointer of the vacuum gauge should not swing too much; excessive swinging may indicate vaporization at the inlet. Additionally, the vacuum gauge reading should not be too high; a high reading may indicate that the inlet valve is blocked or stuck, or that the inlet valve flap has fallen off, as well as a decrease in the water level in the suction tank. 2. A low pressure gauge reading may be due to faulty internal components of the pump, severe wear of the sealing rings, etc.