Preparations for VTP Series Vertical Long Shaft Pumps before Operation
1. Adjustment of Axial Clearance
Before commissioning of the pump, the axial clearance between the guide case and the impeller must be adjusted so that the impeller can meet the performance requirements without friction with the guide case. The pump adopts adjusting nut to adjust the axial clearance. The main steps are as follows:
For the newly installed pump, it is often not able to rotate. By adjusting the adjusting nut, the shaft can rotate precisely, and the position of the nut at this time is taken as the starting adjustment point.
The adjustment of the axial clearance is half of the total channeling momentum of the pump. The general total channeling momentum is 6-8 mm, that is, the general adjustment is 3-4 mm. Dividing the adjusting amount by the tooth spacing of the adjusting nut is the number of circles in which the adjusting nut rotates. For example, when the total channeling is 6 mm and the tooth spacing of the adjusting nut is 1.5 mm, the adjusting nut should be rotated two times from the starting adjusting point. After adjusting, screw in the second round nut, or insert the stop and return pin to lock.
<2> After adjusting according to the above method, start the pump and observe whether the ammeter exceeds the rated value of motor current. If the working current of the motor is too large (more than 110% of the rated current), it means that the gap is too small and should be stopped and adjusted a little more. For newly installed pumps, it is required to run for 20 minutes and adjust again. For deep wells with a small amount of sediment, the axial clearance should be increased. The pump is recommended to have more cycles (1/2-1) than the original regulating position to reduce the wear of impellers in operation.
<1> Before the operation of deep well pump, clear water should be fed into the lubricating water hole of pump seat to ensure the lubrication of shaft and bearing.
<2> In the absence of tap water, the pre-wetting water tank with a volume of about 0.2 m3 should be installed. It is required that most of the water in the water tank flow into the deep well pump before starting the motor.
< 3 > In the unprepared water tank, barrel irrigation can be used temporarily, but the irrigation water should not be less than 0.1 m3.
3. Pre-start inspection
At least the following items should be checked before starting the long-axis pump: foundation installation, adjustment of axial clearance, pre-tightening of packing cover, pre-lubrication, motor lubrication, electrical device and rotational flexibility of pump rotor. When the inspected items meet the requirements, the deep well pump can be started.