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1、 Overview


1. Classification of axial flow pumps


The water pump in which the liquid flows along the axial flow pump is called the axial flow pump. Axial flow pumps are divided into zlb, zlk and zldb axial flow pumps. At present, zlb and zlk are widely used, and there is a trend towards zldb in recent two years.


2. Product specification


The axial flow pumps manufactured by the company are (the old models are in brackets)


250ZL-2.5; 250ZB-4(250ZLD-4); 300ZLDB(12ZLDB); 350ZLB(14ZLB); 500ZLB(20ZLB); 700ZLB(28ZLB); 800ZLB(32ZLB); 900ZLB(36ZLB); 1000ZLB; 1200ZLB; 1300ZLB; 1400ZLB; 1600ZLB; 350ZLDB-1000ZLDB; 1200ZLDB-1800ZLDB; 700ZLK-2(28WZL); 800ZLK-2(32WZL); 1000ZLK-2(38WZL); 1000ZLK-3; 350zlb, 500zlb, 600zlb, 700zlb, 800zlb, 900zlb and 1000 ∽ 1600zlb two-way water axial flow pumps.


2、 Simple calculation description


The main technical parameters of axial flow pump are: head, flow, speed, shaft power and efficiency


1. Head (H): refers to the vertical height of the transported liquid from the inlet to the outlet of the water pump, plus the resistance loss of the pipeline, expressed in several "meters" of water column


H=10PJ2/ γ + Z2+V22/2g


Of which:


P2 - pressure at water pump outlet (kg / cm2)


γ— Unit volume weight of liquid transported (kg / L)


Z2 - height from the measured pressure to the water level (m)


V2 - average speed on the section at the measured pressure P2 at the water pump outlet (M / s)


G - gravitational acceleration, with a value of 9.81 M / S2


2. Flow (q): refers to the volume of liquid delivered by the pump per unit time, expressed in (L / s) or (m3 / s).


3. Speed (n): refers to the speed of the shaft of the water pump per minute (R / min)


4. Shaft power (n): refers to the power consumed by the water pump under a certain flow and head when transporting liquid, expressed in kW.


5. Efficiency( η) Is the ratio of the effective power of the water pump to the shaft power of the water pump, expressed in percent.


When the specified number of revolutions of the pump is "n", the flow is "Q", the head is "H", and the shaft power is "n". If necessary, the speed can be reduced to "N2". At this time, the flow will become "Q2", the head is "H2", and the shaft power is "N2". The relationship between them is as follows:


Q2=Qn2/n H2=H(n2/n)2 N2=-N(n2/n)3


The specified number of revolutions of the pump is the maximum number of revolutions of the pump. The user shall not increase the number of revolutions arbitrarily, but it is allowed to reduce the number of revolutions.


3、 Use and maintenance


1. Commissioning:


After the installation of the pump, a test run shall be carried out to check the steering of the pump and eliminate the problems existing in the installation.


2. Start up sequence:


(1) Close the outlet gate valve or check valve.


(2) Add water: add water from the screw hole at the top of the pump body, or open the check valve to pour water into the water outlet pool, or connect the vacuum pump for air extraction and water diversion (when the vacuum pump pumps out the air and water, start the water pump and stop the vacuum pump).


(3) when the engine reaches normal speed, open the large gate valve and adjust the tightness of the packing. If the pump operates and the bearing temperature is normal and the vibration is slight, it can continue to run.


3. Use and maintenance:


(1) When the bearing is lubricated with process oil, the oil level of the bearing body shall be frequently checked and controlled between the two markings of the oil benchmark; when the bearing is lubricated with grease, the oil volume shall be replenished regularly. For 100-350hw pump, remove the front cover and rear cover to replenish, and for 400-650hw pump, replenish through the oil cup.


(2) Check the temperature rise of the bearing frequently. Generally, it shall not be higher than the ambient temperature by 40 ℃ and the maximum temperature shall not exceed 80 ℃.


(3) Pay attention to whether there is friction and impact sound when the pump is running. If the pump cover rubs with the impeller, a paper pad can be added between the pump cover and the pump body. The actual use clearance is 0.3-0.7mm.


(4) The adjustment of the packing must be appropriate. The liquid shall leak out in drops from the packing gland. If the packing is too tight, the shaft will heat and increase the power; if the packing is too loose, the liquid will leak too much and the efficiency will be reduced.


(5) If the motor is directly connected with the pump, the axis lines of the two shafts shall be in a straight line.


(6) Check the water inlet pipeline for air leakage.


(7) Pay attention to whether the power increases or decreases suddenly and whether the flow decreases suddenly. If so, stop and eliminate it.


(8) Regularly check whether each bolt is loose due to vibration.


(9) In winter, drain the water in the pump and pipeline after shutdown.


(10) The lubricating oil (grease) shall be changed after the pump is used for 200 hours or half a year at the initial stage. The oil shall be changed once after 1000 hours or a year


(11) The pump shall be disassembled for inspection and maintenance after 3000 hours of operation for three years.


(12) For the pump that has been out of service for a long time, the operating part shall be removed and properly kept after rust prevention treatment.


4、 Possible faults and troubleshooting


1. Pump overload


Possible faults:


(1) Blade installation angle exceeds the specified value


(2) The lift is too high or the outlet pipeline is blocked or the gate valves of the outlet pipeline are not fully opened


(3) The water inlet pipe is blocked


(4) The speed exceeds the specified value


(5) There is friction between the outer circle of the impeller and the impeller shell


(6) There are sundries on the blade


(7) The water inlet tank does not meet the design requirements


Troubleshooting:


(1) Adjust the blade angle to all motor power ranges


(2) Clean the water outlet pipeline and open the valve


(3) Clean the water inlet tank


(4) Replace the motor or pulley to make the speed load the rotating speed of the water pump


(5) Readjust and try to eliminate


(6) Clean up sundries and prevent recurrence


(7) If the pool is too small, it should be enlarged; if the center distance between the two pumps is too small, it should be removed; there are vortices in the inlet and outlet, which should be eliminated; if the pump is too close to the pool wall or bottom, it should be enlarged


2. Noise or vibration during water pump operation


Possible faults:


(1) Insufficient water pump intrusion depth


(2) There is friction between the outer circle of the impeller and the impeller shell


(3) The foundation is not firm enough or the foot nuts of pump, motor and transmission device are loose


(4) There are sundries on the blade


(5) Loose pump shaft nut or coupling pin nut


(6) The bearing or shaft sleeve is worn


(7) The blade is broken and damaged by hard sundries


(8) Several water pumps installed in the same pool are improperly arranged and interfere with each other


(9) The pump shaft or transmission shaft is bent or installed out of concentricity


Troubleshooting:


(1) Lower the installation elevation of the water pump


(2) Check the verticality of impeller components and pump shaft


(3) Check and reinforce the foundation and tighten the nuts


(4) Clean up sundries and prevent recurrence


(5) Check and tighten all nuts


(6) Replace the bearing or shaft sleeve


(7) Replace the blade


(8) Rearrange or add partitions in the water inlet tank


(9) Straighten or adjust the pump shaft and drive shaft so that they are on the same vertical line


3. The water pump does not discharge water


Possible faults:


(1) The blade rotation direction does not conform to the design


(2) Insufficient blade penetration depth


(3) The blade is broken and damaged by hard sundries


Troubleshooting:


(1) Adjust the rotation direction of the water pump


(2) Lower the installation elevation of the water pump


(3) Replace the blade


4. Water reduction


Possible faults:


(1) Insufficient entry depth of impeller


(2) Impeller outer circle wear


(3) Lift too high


(4) Speed too low


(5) The blade installation angle does not meet the requirements


(6) There are sundries on the blade


Troubleshooting:


(1) Reinstall according to the installation drawing of the water pump to ensure that the impeller has sufficient intrusion depth


(2) Replace the impeller


(3) Try to adjust the lift to the range of use, and check whether the water outlet pipeline is wrongly blocked


(4) Replace the motor or pulley to make the water pump speed meet the rated speed


(5) Adjust the blade mounting angle


(6) Clean up sundries and prevent accidents