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How should a dosing metering pump be selected for transporting NaOH, and what are the requirements? SUCMC shares an example of a NaOH dosing metering pump, providing detailed information on everything from the principle of the metering pump to the control requirements. Working principle of the metering pump: The motor drives the worm through a coupling, and the worm gear reduces the speed, causing the main shaft and eccentric wheel to rotate. The eccentric wheel then drives the rod to move back and forth inside the guide cylinder; together with the diaphragm, this action creates a vacuum in the pump chamber. As a result, the suction valve opens and liquid is drawn in ； As the diaphragm moves toward the dead center, the intake valve closes while the exhaust valve opens, and the liquid is discharged under the push of the diaphragm. The pump generates a continuous, pressurized, and measured flow of liquid through the reciprocating motion that regulates a certain stroke length. Product structure and drawings of the metering pump: The structure of this pump consists of three parts: the motor, the transmission box, and the cylinder body. The transmission box components consist of a cam mechanism, a stroke adjustment mechanism, and a gear ratio worm gear mechanism ； The stroke of the adjusting tappet is adjusted by turning the adjustment handwheel, thereby changing the expansion and contraction distance of the diaphragm in order to modify the flow rate. The cylinder block components consist of the pump head, suction valve assembly, discharge valve assembly, diaphragms, and their respective diaphragm bases. Control requirements for metering pump products 1) Inspection and preparation before pump operation a Check whether the bolts at all connection points are tightened, and ensure that the machine feet are level; there should be no loose nuts. b Before using the new pump for the first time, the rust preventive grease on the surfaces of all moving parts should be wiped off; metal tools must not be used for scraping. In the rotating box, add 220# worm gear oil or 50# gear oil up to the oil mark, depending on the ambient temperature and the temperature of the medium being transported. d Rotate the coupling to move the diaphragm back and forth several times; there should be no sticking, and the movement should feel smooth. e Check whether the adjustment handwheel is at zero; if not, it should be above zero. (If it is a gauge, it must be zeroed out, as movement of the gauge during transportation can cause drift in its range.) Check that the motor wiring is connected to the appropriate power supply (the wiring method and voltage must comply with the specifications indicated on the motor’s nameplate), and ensure that the pump rotates in the specified direction. 2) To start the motor, it is necessary to check whether the valves on the inlet and outlet pipelines are open before starting the motor; the motor can only be started when the pipelines are unobstructed. b After starting, it should be allowed to run idle for 3 minutes; provided there are no abnormalities, it can then be put into use as needed. c Based on the requirements of the process flow, compare the flow calibration values and curves provided in the certificate with those obtained from actual operating conditions, determine the corresponding percentage values for the stroke, and turn the adjustment knob to the specified scale. After adjustment, the adjustment knob must be locked to prevent it from loosening. The stroke adjustment of pump d can also be carried out while the pump is running after it has been stopped. After the stroke adjustment, it takes approximately 1–2 minutes for the pump’s flow rate to stabilize; the greater the change in stroke length, the longer it takes for the flow rate to stabilize. 3) Operation under load: a Check that the temperature of the regulator and other moving parts shall not exceed 65°C. b After startup, operation should be smooth, with no abnormal noises ； Otherwise, the vehicle should be stopped to check the cause, and the source of the noise must be eliminated before it can be put back into operation. 4) Shutdown: Cut off the power supply to stop the motor from running. SUCMC offers dosing metering pumps as well as accessories such as pulse dampers. For more information, please visit http://www.sucmc.com and http://www.sucmc.cn