Analysis of normal operation and failure of mechanical seals
Hebei Innovation Sealing Material Co., Ltd. provides technical support:
1. Preparation and precautions before starting mechanical seals
a. Thoroughly check the mechanical seals, as well as whether the attachments and pipelines are installed properly and meet the technical requirements.
b. Perform a static pressure test before starting the mechanical seal to check for leaks in the mechanical seal. If there are more leaks, you should find out the reasons and try to eliminate them. If it is still invalid, it should be disassembled and reinstalled. Generally, the static pressure test pressure is 2-3 kg/cm 2 .
c. Press the pump to turn the disc to check if it is light and even. If the car is struggling or not moving, check whether the assembly size is wrong and the installation is reasonable.
2, mechanical seal installation and shutdown
a. Keep the sealed chamber filled with liquid before starting. For transporting the solidified medium, steam is applied to heat the sealed chamber to melt the medium. The car must be driven before starting to prevent the soft ring from breaking due to sudden start.
b. For mechanical seals using the pump external seal system, the oil seal system should be activated first. Finally stop the oil sealing system after parking.
c. After the hot oil pump is stopped, the cooling water of the sealing oil chamber and the end face seal cannot be stopped immediately. When the oil temperature of the end seal is lowered to below 80 degrees, the cooling water can be stopped to avoid damage to the sealing parts.
3. Mechanical seal operation
a. If there is a slight leakage after the pump starts, it should be observed for a while. If the leakage is still not reduced after 4 hours of continuous operation, the pump should be stopped.
b. The operating pressure of the pump should be stable and the pressure fluctuation should be no more than 1 kg/cm 2 .
c. During the operation of the pump, evacuation should be avoided to avoid dry friction and seal damage on the sealing surface.
4. Analysis of typical failure causes of mechanical seals
1) Mechanical seal itself problem
a. The mounting is not in place or uneven.
b. The load factor is too large or the end face specific pressure design is unreasonable.
c. The material is not properly selected.
d. The sealing surface is not flat.
e. The sealing surface is too wide or too narrow.
2) Auxiliary system problems
a. The working conditions are complicated, but there are no auxiliary facilities such as flushing.
b. The flushing tube is clogged.
c. Cooling tube fouling.
3) Media and working conditions
a. The medium is highly corrosive.
b. There are solid particles in the medium.
c. The equipment is evacuated.
d. Sealing surface crystallization.
e. The viscosity of the medium is too large.
4) Pump problems
a. The machining accuracy of the shaft is not good, the string shaft, the jump, and the installation clearance are too large.
b. The vibration is too large after the pump is turned on.
c. The gland ring is not good.
d. The sealed box is not flat.
e. The mechanical seal is not installed to the required amount of compression. (Source: Hebei Innovation Sealing Material Co., Ltd.)
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