Can high outlet pressure of a centrifugal pump damage the mechanical seal?
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The existing centrifugal pump, with a head of 250 meters, is experiencing gradual blockage in the downstream system; in order to maintain the liquid flow rate, it is necessary to increase the frequency of operation of this pump. As a result, the pressure at the pump’s outlet reaches 2.8 MPa, or even higher. The cooling water used to cool the pump’s seal began to carry liquid material outwards, and over time the amount of liquid material flowing out increased, until the material started to spray directly from the seal. The pump manufacturer determined that the reason for this was the excessively high pressure at the pump’s outlet, which exceeded the pump’s capacity, causing the seal springs to compress and fail to return to their original shape, thereby leading to leakage of material. Centrifugal pumps generally have a rated flow rate and head. I would like to ask everyone a few questions: 1. Can the outlet pressure of a centrifugal pump exceed its rated head when it is in operation? 2. Does operating beyond the specified head really cause damage to the mechanical seal? 3. If the head is converted into pressure, does this pressure represent the pressure at the pump outlet, or the pressure difference between the inlet and outlet? I would appreciate it if experts from the equipment area could provide some guidance. Thank you.
The pump operates in accordance with the performance curve; exceeding the head basically results in reduced efficiency, which is uneconomical! The outlet pressure gauge shows the outlet pressure; high outlet pressure can cause leakage in the mechanical seal, and it’s hard to say what will happen if it gets damaged
Do not exceed the head; frequent pressure buildup can damage the equipment. The head refers to the outlet pressure.
Frequent pressure buildup can easily lead to motor damage or damage to the mechanical seal, resulting in leaks
This post was last edited by WaterInStone on January 21, 2017, at 09:07. It is possible to operate the pump beyond its rated head; during factory testing, the shut-off point (when the outlet valve is completely closed) is also measured. In the case of centrifugal pumps, the shaft power at the shut-off point is minimal, so it has no adverse effect on the motor. The head of a pump refers to the pressure difference between the inlet and outlet (as an approximate value), that is, the amount of pressure increase exerted by the pump on the fluid. Mechanical seals rely on a liquid film on their sealing surfaces to provide cooling and lubrication; if there are impurities present, they can likely cause blockages and damage to the mechanical seal. For your specific medium, an external water flushing system should be used as the flushing method for the mechanical seal.
Single-stage pump? Under high pressure, the pressure ratio of the sealing ring increases, causing the moving ring to move toward the stationary ring, rather than the spring being compressed and unable to rebound. It is suspected that a deteriorated O-ring is causing the leakage under high pressure!
2.8 MPa – this exceeds the pump’s head pressure; as a result, the pressure at the mechanical seal increases. Once this pressure exceeds the deformation limit of the spring, the mechanical seal will start to leak. But I think the reason for this is that the outlet of the pipeline is not unobstructed; the actual flow rate is not that high. As a result, the liquid circulation for cooling at the mechanical seal is reduced, the temperature of the mechanical seal rises, and eventually leakage occurs.
The outlet pressure will not be greater than the head
Centrifugal pumps generally have a rated flow rate and head. I would like to ask everyone a few questions: 1. Can the outlet pressure of a centrifugal pump exceed its rated head when it is in operation? Yes. 2. Does operating beyond the specified head really cause damage to the mechanical seal? No. 3: If the head is converted into pressure, does this pressure represent the pressure at the pump outlet, or the pressure difference between the inlet and outlet? Import and export pressure difference ； But from your description, it is by using frequency conversion to increase the head; as the power supply frequency rises, the pump’s rotation speed also increases, and both the pump and the mechanical seal have maximum allowable rotation speeds ； The maximum rotational speed is related to two aspects: first, as the speed increases, the power required by the pump rises, and once it reaches a certain level, it exceeds the pump’s designed load capacity. 2. As the rotation speed increases and the load grows, the vibration also increases ； I suggest you replace it with a new pump; a decrease in flow rate will result in a slight increase in the pump’s head pressure.
Overpressure can damage the mechanical seal, as the design of this seal takes into account the pressure difference between the inlet and outlet; the molding of components such as springs is also based on these pressure parameters.