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How is the fire pump started and operated and how is the mechanical seal of the centrifugal pump checked

2020-08-14
A, install,
1. Check the intact condition of the pump before installation.
2, the pump installation location should be as close to the water source as possible.
3, there are two ways to install the pump and the base, one is directly installed on the cement foundation of the rigid connection, the other is the use of JGD shock absorber installed flexible connection.
4. The pump can be installed directly with a height of 30~ 40mm (for filling cement slurry) on the foundation, and then the pump can be corrected, and the anchor bolts should be worn well and the cement mortar should be filled. After the cement dries up for 3~5 days, the foundation bolts should be recalculated.
5, when installing the pipeline, the inlet and outlet pipelines should have their own support, should not make the pump flange bear too much pipeline weight.
6, the pump is used for suction occasions, the inlet pipe end should be equipped with a bottom valve, and the inlet and outlet pipeline should not have too many bends, at the same time, no water leakage, air leakage phenomenon.
7. The inlet pipe shall be equipped with a strainer to prevent impurities from entering the impeller. The effective area of the filter screen should be 3 ~ 4 times of the area of the inlet pipe, in order to ensure the free flow of liquid.
8. For the convenience and safety of maintenance and use, a regulating valve is installed on the inlet and outlet pipelines of the pump and a pressure gauge is installed near the pump outlet to ensure operation within the rated range and normal operation and service life of the pump.
9. If the inlet needs expanding connection, please select eccentric reducing pipe joint.
Starting, running and stopping of units
Second, the starting
1, the pump group is used for suction occasions, that is, when the inlet is negative pressure, the pipeline should be filled with water or vacuum pump water, water filling the pump and the inlet pipeline, pay attention to the inlet pipeline must be sealed, no leakage phenomenon exists. (It is strictly prohibited to start without water before starting, and water must be advanced before starting.)
2. Rotate the rotor several times by hand to lubricate the bearing and check whether there is a collision between the impeller and the seal ring in the pump. If the rotor cannot be started, it should not be started until the cause of the fault is found.
3. Close the gate valve and pressure gauge cock on the outlet pipe to reduce the starting current.
4, try starting, motor steering should be the same as the arrow on the pump, open the gauge cock.
5. When the rotor reaches normal operation and the manometer shows the pressure, gradually open the exit gate valve and adjust it to the required working condition.
Three, operation
1, the pump group in the transport, must pay attention to observe the meter reading, try to make the pump in the nameplate specified flow head near the work, strictly prevent large flow operation.
2. Regularly check the motor current value shall not exceed the rated current.
3. The bearing temperature of the pump group shall not be higher than 75℃ and shall not exceed the external temperature of 35℃.
4, the pump group at the beginning of the operation should relax the packing gland, when the expansion of graphite or packing completely expanded before adjusting to the appropriate degree.
5, wear parts too much wear should be replaced in time.
6. If any abnormal phenomenon is found, stop the machine immediately to check the reason.
Four, downtime
1. Close the gate valve on the outlet pipe and the vacuum gauge cock.
2, stop the motor, and then close the pressure gauge cock.
3, if there is a cold winter season, the pump should be full of liquid, so as not to freeze crack.
4. Remove the pump, clean the oil and keep it properly after long-term disuse.
Stainless steel multistage centrifugal pump is mainly used for conveying clean water and liquid with physicochemical properties similar to water. Its great advantages are advanced hydraulic model design, high efficiency, high energy saving. The inner impeller, pump casing and its main parts are made of stainless steel, the flow passage is especially smooth, the bearing shell and the sleeve are made of hard alloy, which have super long service life and avoid secondary pollution. The high temperature of the liquid does not exceed 80℃. It is widely used in mine drainage, factory and urban water supply.
In order to ensure that the stainless steel multistage centrifugal pump assembly mechanical seal no leakage, stainless steel multistage centrifugal pump seal inspection is essential, but the inspection process is also more complex, the following more detailed operation steps:
1. Measure the length of the static ring anti-rotating pin and the depth of the pin hole to prevent the pin from being too long and the static ring cannot be assembled in place. This situation can damage the mechanical seal.
2. Check the clearance between the moving ring, stationary ring and the shaft or shaft sleeve. The inner diameter of the stationary ring is generally 1-2mm larger than the axial diameter.
3. Measure the sealing surface size of moving ring and static ring. This data is used to verify the radial width of the stationary and static rings. When different friction materials are selected, the radial width of the friction surface of the hard material should be 1-3mm larger than that of the soft material, otherwise it is easy to cause the edges of the hard material end face to be embedded into the soft material end face.
4. Measure whether the length of the compensation spring changes. The change of spring performance will directly affect the specific pressure of mechanical seal end face. In general, the length of the spring will be shortened after a long period of operation, and the mechanical seal of the compensation spring on the moving ring will be deformed due to centrifugal force.
5, stainless steel multistage centrifugal pump mechanical sealing force check. We usually talk about the mechanical seal tight force is the end face specific pressure, the end face specific pressure to be appropriate, too large, will make the mechanical seal friction surface heat, accelerate the end face wear, increase friction power; Too small, easy to leak. Face specific pressure is determined in the mechanical seal design, we can only be determined by measuring the mechanical seal tightness in the assembly. The normal measurement method makes the measurement of the vertical distance between the end face of the static ring installed and the end face of the gland, and the measurement of the vertical distance between the end face of the moving ring and the end face of the gland, the difference between the two is the tight force of the mechanical seal.