Pumps that start frequently
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Our company has many pumps that are started frequently due to process needs. These pumps have high failure frequency, mainly due to mechanical seals. The mechanical seals will spray materials the moment they are opened. I am begging for professional answers.
I don’t know how your pump is used. 1. First of all, confirm whether the pump that is started frequently can be filled with liquid after stopping the pump, that is, there must be no air. If there is air, it must be fully exhausted before starting the pump. Failure to exhaust may easily cause dry wear of the seal. 2. The medium temperature is not much different from the pump temperature after the pump is stopped. Thermal shock can also easily cause seal leakage. 3. The axial force will change before and after the pump is started.
The poster's pump is self-priming. Is it a horizontal pump like an underground pump or a horizontal self-priming pump? I agree with what the moderator above said, if it is a self-priming pump, it is necessary to prime and exhaust the pump before starting it, and it cannot be careless at all. Of course, if the pump is not self-starting but is manually started and stopped frequently, I personally wonder whether it is due to improper manual operation (such as improper valve opening and closing, mechanical seal leakage caused by evacuation)? ?
I encountered the same problem. The centrifugal pump seal is a WB2 mechanical seal. The customer's material is something similar to tar. The temperature is around 100 degrees. There is no problem under normal operating conditions. After shutdown, the material cools down and turns into a gel state. When it is started again, the mechanical seal will leak. What is the reason for this? How to deal with this problem?
Due to the characteristics of this material, the only way to insulate the pump cover is to ensure that the medium at the seal does not solidify. The WB2 seal is an external seal. The form of the seal is not conducive to preventing leakage, because the medium diffuses outward under the action of centrifugal force, and the medium is inside the seal. If it is an internal seal, consider external flushing.
I think the pump body is insulated and the machine seal uses double-end heated water circulation. I don’t know if the effect will be good.
Regardless of the temperature of the hot water, the lubricity of water exceeding 80 degrees Celsius will be very poor.
Pumps in chemical companies frequently start and stop. If there is leakage or even material spraying from the machine seal, it must be a mismatch between the medium, the pump and the machine seal. If there are no large particles or condensation in the medium itself, then it is also important to reselect the mechanical seal model or lining material, and the installation method. If it is a media problem, the pump needs to be replaced.
My purpose of using hot water is not to lubricate, but to prevent the material from cooling and caking at the machine seal after the machine is shut down.
With double sealing, the hot water for external flushing needs to be turned on all the time, so the temperature of the hot water needs to be considered. If the temperature is high, the sealing surface will not form a good liquid film, and it will still not be used.
Adding insulation is only one way, but it is very troublesome to have to dismantle it every time for maintenance. I suggest adding a jumper line to the outlet pipeline to allow reverse circulation when the pump is out of service, but you must ensure that the pump cannot be reversed.