Is smoke coming from the pump body?
Thread Content
Today, a centrifugal pump was overhauled. After replacing the mechanical seal, the pump was started up for testing; a few minutes later, gray smoke began to emerge from the area around the seal gland. It was clear that the shaft sleeve had burned red, so it was decided to shut down the pump immediately. The maintenance staff were checked, and it was confirmed that the seal springs were installed properly, not too tight, and lubricant was applied to all components such as the O-rings during installation. Testing continued without any treatment, and everything was normal after the testing. The medium transported by this pump in our factory is thiamine mother liquor. The pump is equipped with a single-stage seal using large springs, and no cooling water is required for this seal. This is the first time I’ve encountered such a situation; I would like to ask everyone what could be the reason? The pump model is LCZ50-160
The bushings have all turned red; if the temperature of the fluid being transported is not high, it’s likely that local friction is causing the heating. However, such a problem should not arise after just a few minutes of operation.
There could be several possibilities: 1. No liquid was introduced during testing, or the gas inside the pump was not removed, resulting in frictional heating of the mechanical seal. 2. The rotating ring seat was not fixed tightly to the shaft sleeve, which caused friction; after the pump stopped, the rotating ring seat stuck to the shaft sleeve, but operation resumed normally once the pump started again. 3. The stationary ring seat of the mechanical seal was fitted too tightly to the shaft sleeve, leading to friction
The bushings have changed color; it’s likely due to dry grinding as no fluid entered the sealing chamber
I would like to ask the original poster: will this medium crystallize after stopping circulation for a while? If so, it is likely that the pump was evacuated during the early stages of the experiment due to crystallization or similar reasons, resulting in the absence of a medium
That happens only when iron is rubbed against other iron; it returns to normal after rubbing.
I think it’s because no fluid was introduced during testing or the gas inside the pump wasn’t removed; as a result, there was dry friction between the stationary and rotating rings of the mechanical seal. However, the shaft sleeve shouldn’t turn red. Another possibility is that the set screws holding the rotating ring in place weren’t tightened properly, leading to friction. After the pump was stopped, the rotating ring seat stuck to the shaft sleeve, but everything returned to normal once the pump was started again
Thank you all for your guidance. After analysis, we concluded that air was not completely removed from the pump before the trial run, which led to dry friction of the mechanical seal. During the second trial run, the pump inlet was fully opened and air was also released from the pressure gauge connection, which enabled the operation to succeed. Thank you all