How to check whether the inlet pipe of self-priming pump leaks？
Self-priming pump relies on the high-speed rotation of impeller to generate a low-pressure area in the self-priming pump to absorb water, so the self-priming pump must ensure that its water inlet pipe does not leak, that is, the outside air cannot enter the water inlet pipe. Otherwise, it will not only affect the efficiency of the pump, but also produce serious vibration and noise when the pump operates.
There are several simple and easy methods to check the leakage of pump inlet pipeline:
(1) Duck feather method: use a duck feather to approach the suspected inlet when the pump is running, and observe the floating of the duck feather. In the same way, you can use lighted cigarettes to operate in this way. Through the floating direction of duck down hair and smoke to help find.
(2) Engine oil method: For air inlet points that are difficult to find out, a little engine oil can be coated on the determined approximate air inlet, and the air inlet is the place where the engine oil is sucked away quickly.
Measures to prevent air intake of self-priming centrifugal pump
1. The installation position of self-priming pump should be as close to the water surface as possible to ensure that air is not sucked in when the water level drops.
2. When installing the water suction pipeline, the water inlet horizontal pipe should be slightly inclined downward or installed horizontally in the direction of incoming water, and the water inlet pipe should not be higher than the water inlet of the pump at any point, otherwise the air in the pipe can not be exhausted.
3. To prevent leakage of filler culvert. The tightness of packing culvert should be appropriate, and if it is too loose, the packing gland should be tightened; Packing damage, failure, should be replaced in time; The water seal pipe at the packing cover is blocked and heated, which will cause the packing cover to leak, so the water seal pipe should be cleaned.
4. Before installing the water inlet pipe connected by flanges, clean the plane where the two flanges are in contact with each other, add a rubber pad with a thickness of 3~5mm in the middle, and tighten the bolts symmetrically and step by step.
5. The bottom valve of self-priming pump should have sufficient submerged depth, which should be equal to 1.5~2 times of the outer diameter of the bottom valve from the valve plane, at least not less than 0.5m. If submerged too shallow, it is easy to form vortex, which will suck in air, generate cavitation and damage impeller and pump casing. If it is found that the inlet water level drops rapidly when the pump is running, several wooden boards can be placed on the water surface to reduce the vortex and prevent air from entering the pump casing.
6. The self-priming pump body is provided with a deflation plug. To facilitate deflation, a faucet with the same thread size can be used instead of the deflation plug, and the faucet can be turned on when deflating.
7. The vacuum degree at the suction port of the self-priming pump is limited. If the vacuum degree is too large, it is easy to vaporize the water in the pump, which is unfavorable to the self-priming pump. Therefore, each suction pump has its maximum allowable suction range, which is generally between 3 and 3~8.5m, and should be controlled within this range during installation.
8, pay attention to exhaust. Adequate water diversion should be added before starting the self-priming pump to eliminate the air in the self-priming pump; At ordinary times, the air bleed plug on the pump cover should be opened regularly to remove the air accumulated in it.
When starting the self-priming pump: pay attention to whether the rotation of the pump shaft is correct. Pay attention to whether there is any abnormal sound and vibration during rotation. Pay attention to the readings of pressure gauge and vacuum gauge. After starting, when the readings of pressure gauge and vacuum gauge fluctuate for a period of time and indicate stability, it means that the self-priming pump has been filled with liquid and entered into normal infusion operation.
Before the self-priming pump enters the normal infusion operation, that is, during the self-priming process, special attention should be paid to the rising water temperature in the pump. If the process is too long and the water temperature in the pump is too high, stop the pump to check the reasons. If the temperature of the liquid in the self-priming pump is too high, it is difficult to self-prime, so you can stop the machine temporarily, use the liquid in the discharge pipeline to flow back into the pump or directly replenish the liquid into the pump at the liquid storage port on the pump body to cool the liquid in the pump, and then start it.
