What is the effect of a broken check valve at the outlet of a centrifugal pump on the pump? What are

Centrifugal pump. Outlet check valve.

Effect of damage on the pump].

1. If the check valve cannot be opened, the liquid can only circulate in the pump casing, which will overheat the pump;

2. In the process of stopping the pump, if the power is cut off first, the outlet check valve does not work (the opening of the check valve is limited, or it cannot be opened), it will cause the pump to reverse, the high-pressure liquid will quickly reverse through the outlet valve, and the impeller will reverse; Once the impeller is reversed, the impeller cap will easily fall off, and the impeller will also fall off. It also causes damage to the shaft and seal of the pump under the action of opposite two-way torque.

Centrifugal pump is to use the rotation of the impeller to make the medium centrifugal movement to work. Before the pump starts, the pump casing and suction pipe must be filled with medium, and then the motor is started to make the pump shaft drive the impeller and the medium to do high-speed rotation motion, and the medium undergoes centrifugal motion, which is thrown to the outer edge of the impeller and flows into the pump pipeline through the flow channel of the volute pump casing.

If it is only for the pump, no matter whether the outlet is fully closed or fully open in a short period of time, it has no impact on the pump, if it is for a long time, the vibration of the pump in these two states will be great, and the life of the pump parts will be shortened, if it is in the state of full open outlet for a long time, the motor may be overpowered, the motor may burn out, and what other consequences will occur to the system where your pump is located.

If the check valve cannot be opened, the pump cannot open the medium, the pump current is low, and the pump body is heated (the liquid pump casing circulates and heats).

If the opening is limited, or the opening is incomplete, the pump flow rate decreases, the current is lower than normal, if there are other pumps in parallel at the same time, after the fault valve pump stops the pump, the pump will reverse, the medium will flow backwards, and the impeller of the pump may be loose (determined by the installation form of the pump impeller), damaging the pump.

If the check valve is fully open and cannot be closed, the damage to the process and pump during normal operation is smaller than the previous one, but the damage to the pump and the process after the pump is stopped is greater than the previous one.

I also think that opening the outlet valve to start the pump is too cautious, I have a high head pump here, basically open one-third of the valve position to open the pump, theoretically and full opening is not much different, and I didn't find anything wrong, maybe we are too cautious!

Reply 1st floor: How many questions do you have in this question and you**. 1. Keep the outlet valve closed before the pump (including the standby pump) starts, not only to avoid the motor overload protection caused by excessive motor starting current, but also to protect the pump body itself, because the start of the impeller of the pump first contributes to the pressure difference, if it is the start of a high-pressure differential pump or a multi-stage pump, it will produce a huge reverse force, which must be balanced by the pump body, which will lead to the wear or direct damage of seals, bearings and other components. 2. The inlet and outlet valves of centrifugal pumps in foreign factories are always open, which does not mean that this is necessarily right.

Maybe they're doing it wrong. 3. If you start a pump of about 300kw, there is no problem with starting with load, the motor does not jump, and the pump runs without problems, which cannot be proved to be no problem. For example, if you safely jumped from the 3rd floor to the ground without an accident, do you dare to do it ever since?

4. Not all centrifugal pumps are required to close the outlet valve to start, there is really such a design, the centrifugal pump is started under the condition of fully open outlet valve. This design is rare. Therefore, the starting equipment must be carried out in accordance with the operation method of this equipment, and it must not be careless, otherwise there will be problems.

Welcome to discuss.

Summary. Hello dear, after the centrifugal pump starts the pump, if the outlet valve is not opened, the pump will not be suffocated. In actual operation, just starting, the current increases instantaneously and decreases immediately, and the pump outlet opens wide, and the current increases.

The heat generated by the fluid cannot be taken away by the fluid if the outlet valve is not opened for a long time, and it accumulates in the sealing cavity, which is easy to cause seal leakage. On the curve of the pump, you can see the power performance of the pump, the power of the outlet valve is closed, and the power of the pump is based on the performance curve of the pump design, with the smallest flow, the lowest power, and the highest head. When the pump is opened, it is possible to close the pump outlet valve for a short time to reduce the starting current of the pump, but the time should not be too long, and the time is too long to be harmful to the pump.

Extended information: Centrifugal pump start-up process precautions: There is a limit value for the head generated by the centrifugal pump at a certain speed.

After the centrifugal pump starts the pump, if the outlet valve is not opened, is there such a thing as suffocating the pump?

Hello dear, after the centrifugal pump starts the pump, if the outlet valve is not opened, the pump will not be suffocated. In actual operation, just after the cheating starts, the current increases instantaneously, and immediately decreases, the pump outlet is opened, and the current increases. If the outlet valve is not opened for a long time, the heat generated by the fluid cannot be carried away by the fluid, and it accumulates in the sealing cavity, which is easy to cause seal leakage.

On the curve of the pump, you can see the power performance of the pump, the power of the outlet valve is closed, and the power of the pump is based on the performance curve of the pump design, with the smallest flow, the lowest power, and the highest head. When opening the pump, it is possible to close the pump outlet valve for a short time to reduce the starting current of the pump, but the time should not be too long, too long will be harmful to the pump, close the port valve for a long time, the medium in the pump body will be vaporized due to the increase in temperature, forming cavitation, which is easy to cause the pump to vibrate violently and cause damage to the machine seal and bearing. Additional Information:

Precautions for the starting process of centrifugal pump: There is a limit value for the head generated by the centrifugal pump at a certain speed.

The outlet valve has not been discredited with guessing that it is not a sign of trouble, not suffocating, because the valve is closed, the power of the pump is also very large, about half of the rated power, the flow rate is 0, the efficiency is also 0, the power is all lost and heated, if the time is a little longer, the water in the pump will be boiled, and the sealing may have problems. For the Liqing Nianxin pump, the purpose of closing the valve to start is to start the power is small, and the valve should be opened quickly after starting.

No, the pressure of the pump body is much greater than the pressure generated by the operation, and the operation of the pump is like this, first close the outlet valve, and then slowly open the outlet valve to achieve the required head and flow rate.

No, centrifugal pumps are not positive displacement pumps, and the pressure at the impeller will increase after closing the outlet valve, and when it rises to the same level as the outside atmospheric pressure, the water will not be pressurized, which is equivalent to the impeller stirring in the water. It doesn't have any effect, but it burns out if it lasts for a long time, but it's not suffocating.

The outlet valve has not been opened, it is not suffocated, because the valve is closed, the power of the pump is also very large, about half of the rated power, the flow rate is 0, the efficiency is also 0, the power is all lost and heated, if the time is a little longer, the water in the pump will be boiled, and the sealing may have problems.

For centrifugal pumps, the purpose of closing the valve to start is to start the power is small, and the valve should be opened quickly after starting, and it is best to start with a small opening, not to close it.

In addition, the stability of the pump is poor and the vibration and noise are high at a small flow rate.

The current of the centrifugal pump motor rises with the increase of the flow rate, and when the flow rate is zero, it is equivalent to the idling of the water pump.

When it is not completely blocked, the flow rate becomes smaller, the motor current becomes smaller, and the motor will not be burned.

When completely blocked, the motor current becomes much smaller and will not burn the motor. Since the flow through the pump is zero, there is nothing wrong with running the pump for a short time, but when it is running for a long time, the water temperature in the pump casing will rise sharply, and even vaporize the water, which may damage the shaft seal of the pump. If the temperature of the pump body rises, causing other mechanical changes, such as holding the shaft, jamming, etc., it is not excluded that the motor will be burned.

It will lead to poor water flow and finally the motor will burn out.