Installation requirements for pumps

This post was last edited by luoshirong on 2010-8-21 at 23:20. It’s copied from my notes; I hope it will be useful to you: Pump assembly and disassembly: Before assembling the pump, all components should be inspected. The mating surfaces of the components, especially those of the mechanical seal, must be cleaned thoroughly. The sealing surfaces should not have any visible scratches, cracks, or other defects; if such defects are present, the components need to be replaced. Assembly: Press the water seal onto the motor shaft, and secure the middle base to the motor with bolts. After applying a lubricant such as Vaseline to the rubber ring of the stationary ring in the mechanical seal, press the stationary ring assembly axially into the middle housing; apply clean grease to the sealing surface, install the other sealing components, add the flat keys, impeller, and retaining washers, and secure them with bolts. Note: The sealing rubber ring of the mechanical seal’s static ring is prone to shifting to one side during installation, which can cause leakage in the seal; careful inspection should be carried out during installation. Apply an appropriate amount of grease to the sealed end face in the middle, and install the O-ring. When installing the O-ring, the sealing ring is prone to falling off or folding; be careful to avoid leaks. Lift the motor assembly with the impeller facing downward, slowly insert it into the pump body, then secure it with bolts. Install the various pipe plugs and vent plugs as well. Turn the rotor by hand to check for any sticking. Dismantling: Follow the steps in reverse order to installation. Note: When removing the mechanical seal, do not use a hammer or iron mallet to strike the stationary ring directly; instead, use wood to tap gently in order to remove the stationary ring slowly. If dirt accumulation makes disassembly difficult, it should be cleaned first before attempting to disassemble it. Installation, operation, and maintenance of the unit: Installation: During installation, it should be placed as close as possible to the liquid being transported, so that the pump is located at a point with the lowest suction height and the shortest suction pipeline. Note: It is necessary to ensure that there is a distance of at least 150 mm between the unit and any surrounding obstacles, so that the motor fan can have adequate access to air. When the pump is used in environments with strict vibration requirements, shock absorbers (shocks) can be used, and they must be installed in accordance with the manufacturer’s instructions. The piping should be fixed securely, and the pipe supports near the pump flange must have sufficient rigidity to prevent the pump from bearing the weight pressure of the piping. The installation of the pump set should be protected from direct sunlight and rain. A vacuum gauge should be installed at the pump’s inlet, and a pressure gauge should be installed on the outlet flange to monitor and control the pump’s operation. The range of the pressure gauge should be 2 to 3 times the actual pressure, which is appropriate. Gate valves should be installed on the inlet and outlet pipelines of the pump to facilitate maintenance and operational adjustment. Wiring: The wiring must be carried out in accordance with the requirements specified on the nameplate. During wiring, the connections must be secure; any looseness is not allowed, as this can lead to poor contact and result in engine damage due to missing phases. To ensure the reliable operation of the motor, an overload protection device should be installed at the electrical switch, and the setting value of this protection device should be adjusted according to the current requirements specified on the motor’s nameplate. Warning: If an overload protection device is not installed, the motor may be damaged due to overload caused by an increase in current under conditions such as when the water outlet valve is fully open, during operation at high flow rates, or in other similar situations. In the suction condition (water level below the impeller axis or water level below the pump inlet axis), at standard atmospheric pressure, the pump’s installation height H_install = 10 – (NPSH)r – 0.5 – hw, where hw represents the resistance loss in the suction pipeline (the units in this formula are meters). When pumping water out of a tank, the length of the straight pipe section ahead of the pump’s suction inlet should not be less than 3 times the diameter of the inlet; moreover, the depth to which the suction pipe’s opening is submerged below the water surface should be more than 1.5 times the diameter of the inlet and at least 500 mm. The distance from the inlet of the suction pipe to the pool wall should be more than 1.5 times the diameter of the pipe; the distance from it to the pool bottom should also be more than 1.5 times the diameter and not less than 500 mm. A filter screen must be installed, with a total area that is at least 2 to 3 times the area of the suction pipe inlet. Note: The horizontal section of the suction pipe should be installed at a slight downward angle against the flow direction to prevent air accumulation. To facilitate filling the forward pump with water before starting it, a bypass valve can be installed on either side of the check valve; this valve is opened before starting the pump to fill it with water, and then closed once it is full, which makes usage easier. For pumps used for supplying water to high-rise buildings or those with an outlet pressure greater than 0.2 MPa, in addition to a gate valve being installed at the outlet, a check valve should also be placed between the pump outlet and the gate valve, to prevent damage to the impeller caused by high-pressure water flowing back in the event of a sudden power outage. Operation: Open the inlet valve and the air release plug, close the outlet gate valve, fill the pump with water, and then close the air release plug. Before starting, use a screwdriver to move the fan blades of the water pump motor in order to check whether the motor rotates smoothly. Start the motor to determine whether the rotation direction of the pump shaft matches the direction indicated on the pump (clockwise when viewed from the motor side). Warning: It is strictly prohibited to run the pump without water to avoid damage to the mechanical seal. With the inlet gate valve fully open and the discharge gate valve closed, start the water pump and turn on the pressure gauge; gradually open the outlet gate valve until the desired operating condition is reached (the operation time should not exceed 3 minutes with the outlet gate valve closed). Make sure that the current drawn by the motor does not exceed its rated value. Note: The flow rate at the operating condition should not exceed the maximum value specified in the performance table. During operation, the actual head H = (P_out – P_in) / 0.0098 should be no less than the head corresponding to the maximum flow rate given in the performance table. (In the formula, P_out is the value read from the pressure gauge at the outlet, and P_in is the value read from the vacuum pressure gauge at the pump’s inlet; pressure is measured in MPa, and head is measured in meters.) The ideal and efficient operating condition is the midpoint given in the performance table, and the outlet gate valve can be adjusted by monitoring the inlet and outlet (vacuum) pressure gauges. When the characteristic curve of the device (piping system) is already determined, if it is necessary to adjust the operating conditions of the pump, the preferred methods are to change the speed or adjust the impeller diameter; for implementation details, please consult the manufacturer. Shutdown sequence: Close the gate valve on the discharge pipeline ---- motor ---- pressure gauge. Maintenance: It is necessary to regularly check whether the operation is smooth, as well as the wear and leakage of the mechanical seal; replace the seals in a timely manner to prevent pressurized water from entering the motor. Regularly check the temperature changes of the motor casing. The pump should operate normally, with the allowable temperature rise of the motor being 80°C. If necessary, further check whether there is any overload or imbalance in the three-phase motor currents. Regularly check the water inlet tank for any floating debris and changes in water level. If the water level in the tank drops below the minimum level, the pump should be stopped to prevent cavitation and damage to the impeller. If necessary, the gate valve can be adjusted to appropriately reduce the pump’s flow rate, thereby helping to raise the water level in the tank. Pay attention to the changes in the pressure gauge and ammeter; if any abnormalities are detected, take appropriate action promptly. When the pump is not in use for an extended period, any accumulated water should be drained, rust should be removed, and anti-rust grease should be applied.

This post was last edited by luoshirong on 2010-8-21 23:24. Cause of the fault and solutions: Cause of the fault – Solution: The pump does not draw in water. 1. There is not enough water in the injection pump. 1. Open the air vent plug, add more water to remove the air inside the pump, and then close the air vent plug. 2. Air leakage in the suction pipeline system or leakage from the bottom valve. 2. Inspect all connection points, reseal them, and repair the bottom valve. 3. Air entrapment in the pipeline. 3. Proper installation: The pressure reaches the specified level, but the water flow is insufficient. 1. High resistance loss in the outlet pipe. 1. Shorten the outlet pipe or increase its diameter. 2. The output height exceeds the pump’s capacity. 2. Re-select a suitable pump. Reduced water output 1. Air has entered the pump. 1. Check the area where air is leaking and seal it. 2. The radial clearance at the impeller throat is too large, causing backflow of water inside the pump. 2. Replace the worn impeller. 3. Local blockage in the bottom valve or piping. 3. Shutdown for inspection. 4. Too low voltage at the motor terminal causes a decrease in speed. 4. Stabilize grid voltage. Pump vibration or noise: 1. The unit is not installed firmly. 1. The support area at the pump flange should be reinforced. 2. Air leakage in the suction pipe or insufficient submersion depth of the suction pipe inlet allows air to be drawn into the pump. 2. Seal the leaky area or increase the submersion depth of the suction tube. 3. Cavitation occurs in the impeller. 3. Reduce the pump installation height or increase the suction pipe diameter or raise the inlet pressure, and replace the damaged impeller. 4. Deviation from operating conditions. 4. Operate as closely as possible within the efficient range (nominal point) to avoid running the pump at high flow rates. Motor overheating 1. The ambient temperature is too high, resulting in poor heat dissipation of the motor. 1. Improve the operating environment of the pump, check whether the fan blades are functioning properly, and ensure that the ventilation ducts are not blocked. 2. The motor load is too high. 2. The pump is stuck; shut down for maintenance ； Or the bearing is damaged; replace the bearing ； Or operate the pump at a higher flow rate; adjust it to operate at its rated point and within its efficient range. 3. Excessively high or low voltage, or phase loss. 3. Stabilize the power supply voltage. 4. Water entering the motor. 4. Disassemble the machine, dry it, and perform maintenance to prevent water from entering the motor through gaps in the shaft holes or the wiring box. The leaky seal is damaged; replace the seal (shaft seal or O-ring)