Trouble shooting of centrifugal pump without water

The centrifugal water pump is widely used in agriculture because of its simple structure, convenient use and maintenance, and high efficiency, but it is also annoying because it can't carry water. The reason for not deliberately obstructing Sheung Shui is analyzed.

1. There is air in the water inlet pipe and the pump body
1. Some users have not filled enough water before starting the pump; it seems that the irrigation water has overflowed from the vent hole, but the air is completely discharged without rotating the pump shaft, causing a little air to remain in the water pipe or the pump body.

2. In contact with the pump, the horizontal section of the inlet pipe should be lowered by more than 0.5% against the direction of water flow. The end connected to the pump inlet is high, not completely horizontal. If it is tilted upward, air will remain in the water inlet pipe, which reduces the vacuum in the water pipe and the pump and affects water absorption.

3. The pump packing has been worn out for a long time or the packing is too loosely pressed, causing a large amount of water to be ejected from the gap between the packing and the shaft sleeve of the pump. As a result, external air enters the pump from these gaps, which affects the water extraction.

4. Due to the long-term diving, the inlet wall has holes due to corrosion of the pipe wall. After the pump works, the water surface continues to decline. When these holes are exposed, the air enters the inlet pipe through the holes.

5. There are cracks at the inlet pipe bend, and there is a slight gap at the connection between the inlet pipe and the pump, which may cause air to enter the inlet pipe.

Second, the pump speed is too low
1. Human factors. A considerable number of users are randomly equipped with another motor to drive due to the damage of the original motor. As a result, the result is less flow and low head.

2. The drive belt is worn. Many large water pumps use belt transmission. Due to long-term use, the transmission belt wears and loosens, slipping occurs, reducing the pump speed.

3. Improper installation. If the center distance of the two pulleys is too small or the two shafts are not parallel, the tight edge of the transmission belt is installed on the top, resulting in a too small wrap angle. The calculation error of the diameter of the two pulleys and the larger eccentricity of the two shafts of the coupling drive pump will cause the pump Speed ​​changes.

4. The mechanical failure of the pump itself. The loosening of the fastening nuts of the impeller and the pump shaft or the deformation and bending of the pump shaft cause the impeller to move more, directly rub against the pump body, or damage the bearings, which may reduce the speed of the pump.

5. Power machine maintenance is not recorded. The motor is demagnetized due to the burning of the winding. The number of winding turns, wire diameter, wiring method during maintenance, or failure to completely eliminate the factors during maintenance will also change the speed of the pump.

Third, the suction stroke is too large
Some water sources are deeper, and some water sources are flatter on the periphery, ignoring the allowable suction range of the pump, resulting in little or no water absorption. It is necessary to know that there is a limit to the degree of vacuum that can be established at the suction port of the pump. In absolute vacuum, the suction stroke is about 10 meters of water column height, and it is impossible for the pump to establish absolute vacuum. If the vacuum is too large, it is easy to vaporize the water in the pump, which is not good for the pump. Each centrifugal pump has its large allowable suction stroke, generally between 3 and 8.5 meters. When installing the pump, it is not necessary to be simple and convenient.

4. The resistance loss of water flowing into and out of the water pipe is too large
Some users have measured that the vertical distance from the reservoir or water tower to the source water surface is slightly smaller than the pump head, but the amount of water lifted is small or the water cannot be lifted. The reason is often that the pipeline is too long, there are many bends in the water pipe, and the resistance loss in the water flow pipe is too large. Under normal circumstances, 90-degree elbows have greater resistance than 120-degree elbows. Each 90-degree elbow has a head loss of about 0.5 to 1 meter, and every 20 meters of pipe resistance can cause a head loss of about 1 meter. In addition, some users are also free to pump the inlet and outlet pipe diameters, which also have a certain impact on the head.

1. What is a Fuel Tanker Trailer?

Fuel tanker trailer are mainly used for transport liquid and oil. The tank body is generally made of carbon steel sheet, and it can also be made of aluminum alloy, stainless steel, polyethylene and other materials.


The tank body has sufficient strength. There are anti-shock plates inside the diesel tank trailer. There are manholes and liquid discharge valves in the tank accessories. One of our fuel tanker trailer can transport two kind of oil, it can be divided into tanks. Common tank material is carbon steel Q345, thickness is 4mm-6mm national standard steel plate.

(1) What are the common types of fuel tanker trailer?


Petrol tanker trailer material: carbon steel, stainless steel, aluminum alloy, pure aluminum tank, rubber-lined, rotomolded, plastic tank, glass steel tank can also be used as required


Tanker trailer body types: square, oval, round.


(2) How many the tonnage and volume of the fuel tanker trailer?


Storage tanker trailer transport tonnages are 30 tons, 40 tons, 50 tons, etc. The volume of petrol tanker trailer often purchased are 30 cubic meters, 35 cubic meters, 40 cubic meters, 45 cubic meters, 50 cubic meters, 55 cubic meters, and 60 cubic meters.


(3) What can the petrol tanker trailer transport?


Diesel tank trailer mainly transport gasoline, diesel, crude oil, lubricating oil, olive oil, soybean oil, olive oil, alcohol, edible oil. Stainless steel tanker trailer can also be used to transport chemical products such as sulfuric acid, hydrochloric acid, phosphoric acid and caustic soda. raw material.




If you want oil fuel tanker truck trailer capacity, specifications, dimensions for sale craigslist, welcome to contact us.




2. Package and transportation of oil tank trailer

Fuel tanker trucks trailer for sale usually adopt by bulk carriers or ro-ro ships. We spray wax on the tank. Cover it with a waterproof rain cloth.


Some countries can also ship by container or frame cabinet.

3. What`s the bottom filling of the storage tanker trailer?

(1) Bottom loading system of the storage tanker trailer


In the previous Fuel Tank Semi Trailer, we pour oil into the tank from the manhole above the tank trailer.Add a special oil pump at the rear of the petrol tanker trailer to realize the reverse loading and unloading of diesel.


Now, in order to improve the safety, our fuel tank trailer production has all done the bottom filling process.


What is bottom filling? Important components for bottom filling: The main components of bottom filling are exhaust gas recovery system, anti-spill system, subsea valve, European standard tank mouth, control head, SO2 socket, anti-static system, bottom canned API connector.

(2) European standard aluminum alloy tank cover


Aluminum alloy European standard tank cover is also manhole cover. It`s usually on the top of the oil tank, the tank cover has built-in breathing and emergency exhaust functions. Our diesel trailer has oil and gas recovery valve, oil measuring hole, anti-overflow probe on the manhole cover, etc.


During the filling process of the anti-overflow sensing system, when the liquid level reaches the detection position, the sensing system will automatically alarm to stop the loading of the oil.


The built-in breathing valve keeps the internal pressure of the fuel tank trailer stable and balanced with the external pressure when transporting oil.


Its spill-proof design prevents tanker trucks from being sealed in the event of an accident.


When the pressure of the emergency exhaust device in the fuel tank rises sharply, it will automatically open to release the pressure in the fuel tank, thereby preventing accidents and greatly improving the safety of oil transportation.

(3) Subsea valve


Subsea valve(emergency shut-off valve). Simple operation, time saving, safety and environmental protection.


Pressure-balanced subsea valve is used for multi-compartment tanker trucks, which can carry out separate loading and unloading of different tanks. The three-way design simplifies the pipeline, reduces the load, easy to operate, and safe and reliable.


The pneumatic shut-off valve is installed at the bottom of the tanker tank and can be refueled. The internal pressure of the valve is small, the flow is large, and there is a cut-out groove on the flange of the valve body.If the force is too large, the car body pipeline and the tank body will be automatically disconnected, and the automatic centering plunger and durable spring will still remain sealed, and the medium in the tank will not leak, thereby ensuring the safety of the oil tank.


When we can`t open because there is no air source or other reasons, we can open the cylinder piston rod and open it manually.




4. How to maintain the gas tanker trailer?

In addition to the normal inspection of the braking system and the lubrication system, the gasoline tanker semi-trailer should also pay attention to the following points:


(1) Do not make the tire pressure too high.


If the tire pressure is too high, the ground contact area of the tire will be reduced. The tread wear will be severe, this will reduce the braking effect when braking. There is no doubt that this will affect driving safety; when the air pressure is too high, the tires will easily explode on bumpy roads.


However, too low tire pressure is not good. Too low tire pressure will accelerate tire wear, increase vehicle fuel consumption, and also affect driving safety and vehicle braking effect.


(2) Too much diesel or gasoline filling in diesel tanker trailer. Too much diesel or gasoline can easily block the breathing valve. As a result, steam cannot be effectively eliminated, and pressure is generated inside the tanker truck. Valve damage has occurred.


Fuel Tanker Trailer

Fuel Tanker Trailer

Liangshan Changhong Special Purpose Vehicle Manufacturing Co., Ltd. , https://www.chvehicles.com