Centrifugal water pumps (except self-priming jet pumps) must be filled with water before starting the pump and the water inlet pipe, otherwise,  the pump will not be able to pump water. If the centrifugal water pump does not produce water after it is started, it is often because the air in the pump has not been drained and the water has not been filled.

There are two main methods of water filling before starting: one is to fill with water by assembling the bottom valve, which is a one-way valve installed at the inlet of the water inlet pipe. The installation efficiency of the water pump; the other is the bottomless valve filling water, the biggest advantage of this method is energy saving, compared with the pumping station with the bottom valve, it can save energy by 10% to 15%. The following introduces several centrifugal water pump water-filling methods for users to choose from when running the pump.

■Self-introduction and water filling method: For semi-submerged pump houses (that is, pump stations where the elevations of the water inlet pipe and the pump top are below the water surface of the water inlet pool), water can be introduced into the pump without manual water diversion. The disadvantage of this kind of pump station is that the water absorption capacity of the pump is not fully utilized, and the installation elevation of the pump is lowered, which not only increases the excavation volume of the foundation but also makes operation and management more inconvenient; but the advantage is also obvious, that is, it is easy to realize the pumping station. Automation, strong timeliness.

■Manual water filling method: For small pumping stations with a water inlet pipe diameter of less than 300mm, there is usually a bottom valve at the inlet of the water inlet pipe, and the manual water filling method is usually used, that is, from the special water filling and vent hole on the upper part of the pump shell. A water-fill funnel (or an upside-down regular bottle with the bottom removed) is filled with water. For small pumping stations with a water inlet pipe diameter of less than 300mm, a bottom valve is usually installed at the inlet of the water inlet pipe, and the pump can also be filled with water from the outlet pipe of the pump (a pump station with a shorter outlet pipe). Since there is no need to purchase other water-filling equipment, this water-filling method is more common in small rural pumping stations.

For small pumping stations without bottom valves, check valves,  and short pipelines, it is also possible to start and fill the pump with water from the outlet pipe at the same time, so as to gradually bring out the air in the pump and pipelines. , Generally, after a few minutes of continuous water filling, the water pump can pump water normally.

■Vacuum water tank filling method: For small pump stations without bottom valves, the vacuum water tank filling method can be used. The vacuum water tank is a closed water tank welded with iron sheets, and its volume is at least three times the volume of the water inlet pipe. The installation position of the water tank should be as close as possible to the water pump, and the bottom height of the water tank should be slightly lower than the axis of the water pump. The height of the vacuum water tank is generally twice the diameter of the water tank.

Before starting the water pump, fill the water tank with water to seal it. After the water pump is started, the water pump enters the water from the vacuum tank. Due to the decrease in the water level of the water tank, a certain vacuum is formed in the water tank. The water pump starts to run normally.

■Jet pump water filling method: When the diesel engine is used to drive the water pump to pump water, the exhaust gas discharged from the diesel engine can be used to pass into the jet connected to the top of the water pump to pump air and fill water, thus removing the bottom valve of the water pump. When the water pump is started, the valve cover connected to the handle is closed, the exhaust gas is ejected from the ejector, and the air in the pump is sucked out through the connecting pipe. After filling with water, the valve cover is opened and the control valve is closed. The benefit of this water-filling method is that the power machine is fully utilized, and the efficiency of the pumping station is improved.

■Self-suspension water diversion filling method: The self-suspension water diversion filling method is realized through the principle of "water-gas replacement" by using the difference in bulk density between water and air. This method can remove the bottom valve of the water pump.

First of all, design a ventilation tank with an appropriate amount of containers. The ventilation tank is generally made of plastic, or it can be a thin iron piece, and the cost is only half of the bottom valve. Then, place the air exchange tank at the water inlet of the water pump to form a connected body with the water pump and the pipeline. At the same time, a ventilation control valve is installed on the ventilation channel between the ventilation tank and the water pump. When filling water, fill the air exchange tank with water in advance, then add a cover to seal it, and then open the air exchange valve. After ventilation is completed, close the ventilation valve and a part of the diversion water will be suspended in the water inlet pipe. Repeat this method several times, the air will be completely exhausted, and the water inlet pipe will be filled with water. At this point, the water pump can be started to carry out the pumping operation. Before shutting down, as long as the gate valve is closed first and then shut down, the pilot water will not sit back. There is no need to refill the diversion water when starting up next time. The advantage of this water filling method is that the price of the ventilation tank is relatively low, the manufacture is easy, the labor intensity is low, and energy is saved.

■Vacuum pump water-filling method: For large and medium-sized pumping stations with a water inlet pipe diameter greater than 300mm, or pumping stations with high automation requirements, a vacuum pumping device is a commonly used water-filling device. It is assembled from a vacuum pump and other equipment. Most of the vacuum pumps often used in drainage and irrigation stations are water ring vacuum pumps.

An eccentric toothed impeller is installed in the cylindrical pump casing of the water ring vacuum pump. The pump casing is filled with circulating water. When vacuuming, the impeller rotates. Under the action of centrifugal force, the circulating water in the pump casing is thrown around the impeller, forming a rotating water ring on the inner wall of the pump casing. And because the impeller is eccentrically installed in the pump casing, the size of the space formed between the water ring and the toothed blades is different. When the impeller rotates clockwise, the space between the two blades on the right half of the impeller gradually increases. Under airtight conditions, as the air volume increases, the pressure decreases, forming a vacuum, and the air in the pump and pipeline passes through The suction pipe enters the crescent-shaped suction port on the right side of the vacuum pump casing, and is sucked into the vacuum pump. The space between the two blades on the left half of the vacuum pump impeller gradually decreases, so the air is compressed and the pressure increases accordingly, and finally passes through the vacuum pump. The crescent-shaped exhaust port on the left side of the pump casing discharges from the vacuum pump and enters the water-air separation box to separate the circulated water and then reuse it. The impeller keeps rotating, and the vacuum pump keeps sucking in and exhausting air, and finally, the water pump is filled with water.

■Manual pump water filling method: As a kind of reciprocating positive displacement pump, a manual pump is widely used in rural areas of our country. Farmers can use their own manual pump as a vacuum pump to fill the centrifugal water pump, which is convenient and economical. The most common usage is: to install the manual pump on the suction hole of the centrifugal water pump or on the water inlet pipe near the water pump to pump air and divert water, making it a tool for filling water when the centrifugal water pump is turned on, thus saving the need for water pump inlet. The bottom valve on the water pipeline reduces energy loss and improves the efficiency of the water pump device.

■Self-introduction and water filling method: For semi-submerged pump houses (that is, pump stations where the elevations of the water inlet pipe and the pump top are below the water surface of the water inlet pool), water can be introduced into the pump without manual water diversion. The disadvantage of this kind of pump station is that the water absorption capacity of the pump is not fully utilized, and the installation elevation of the pump is lowered, which not only increases the excavation volume of the foundation but also makes operation and management more inconvenient; but the advantage is also obvious, that is, it is easy to realize the pumping station. Automation, strong timeliness.

■Self-suspended water diversion and filling method: The self-suspension water diversion and filling method is realized through the principle of "water-gas replacement" by using the difference in bulk density between water and air. This method can remove the bottom valve of the water pump.

First of all, design a ventilation tank with an appropriate amount of containers. The ventilation tank is generally made of plastic, or it can be a thin iron piece, and the cost is only half of the bottom valve. Then, place the ventilation tank at the water inlet of the water pump to form a connected body with the water pump and the pipeline. At the same time, a ventilation control valve is installed on the ventilation channel between the ventilation tank and the water pump. When filling water, fill the air exchange tank with water in advance, then add a cover to seal it, and then open the air exchange valve. After the air exchange is completed, close the air exchange valve and a part of the diversion water will be suspended in the water inlet pipe. Repeat this method several times, the air will be completely exhausted, and the water inlet pipe will be filled with water. At this point, the water pump can be started to carry out the pumping operation. Before shutting down, as long as the gate valve is closed first and then shut down, the diversion water will not sit back. There is no need to refill the diversion water when starting up next time. The advantage of this water filling method is that the price of the ventilation tank is relatively low, the manufacture is easy, the labor intensity is low, and energy is saved.

■Vacuum pump water-filling method: For large and medium-sized pumping stations with a water inlet pipe diameter greater than 300mm, or pumping stations with high automation requirements, a vacuum pumping device is a commonly used water-filling device. It is assembled from a vacuum pump and other equipment. Most of the vacuum pumps often used in drainage and irrigation stations are water ring vacuum pumps. An eccentric toothed impeller is installed in the cylindrical pump casing of the water ring vacuum pump. The pump casing is filled with circulating water. When vacuuming, the impeller rotates. Under the action of centrifugal force, the circulating water in the pump casing is thrown around the impeller, forming a rotating water ring on the inner wall of the pump casing. And because the impeller is eccentrically installed in the pump casing, the size of the space formed between the water ring and the toothed blades is different.

When the impeller rotates clockwise, the space between the two blades on the right half of the impeller gradually increases. Under airtight conditions, as the air volume increases, the pressure decreases, forming a vacuum, and the air in the pump and pipeline passes through The suction pipe enters the crescent-shaped suction port on the right side of the vacuum pump casing, and is sucked into the vacuum pump. The space between the two blades on the left half of the vacuum pump impeller gradually decreases, so the air is compressed and the pressure increases accordingly, and finally passes through the vacuum pump. The crescent-shaped exhaust port on the left side of the pump casing discharges from the vacuum pump and enters the water-air separation box to separate the recycled water and then reuse it. The impeller keeps rotating, and the vacuum pump keeps sucking in and exhausting air, and finally, the water pump is filled with water.