Double-end mechanical seal
Thread Content
What does it mean when the internal seal of a double-end face mechanical seal fails and the seal fluid pressure is lower than the pressure of the medium inside the pump?
This is why the medium enters the sealing fluid (isolating fluid). For the PLAN53A, 53B, and 54 systems, the pressure of the sealing fluid is higher than the pressure in the sealing chamber; when the primary seal (inner seal) fails, the sealing fluid (isolating fluid) enters the pump chamber. If the pressure of the sealing fluid (isolating fluid) decreases and the internal seal fails, the medium will enter the sealing fluid (isolating fluid).
In this case, since the pressure of the isolation fluid is lower than that inside the pump chamber, the medium will flow into the isolation fluid pipeline； As a result, the medium corrodes the sealing system; the mechanical seal is damaged due to a lack of cooling or flushing, and the medium may also leak out from the atmospheric side, causing contamination
The API P52 sealing scheme features a isolation fluid pressure that is lower than the pressure on the medium side but not lower than atmospheric pressure. When the main seal fails and leaks, the isolation fluid gets contaminated by the medium, which reduces its performance; at this point, the level of the isolation fluid in the tank triggers an alarm and the pressure increases!
We’ve learned that we only use single-sided ones
When the internal seal of a double-end face mechanical seal fails and the pressure of the sealing fluid is lower than the pressure of the medium inside the pump, this is what is commonly referred to as internal leakage of the mechanical seal; the medium will leak out through the outlet pipe for the sealing fluid
As written by the original poster, the seal oil tank is connected to the flare line in a direct manner; that is, there is a pipeline from the seal oil (isolation oil) tank that leads to the flare. The valve on this pipeline remains open, and the pressure inside the pipeline is slightly positive. The pressure within the pump chamber is higher than atmospheric pressure. In the event of a leak in the main seal, the fluid will leak into the seal oil system, causing the liquid level in the tank to rise as well as the pressure. A interlocked alarm is triggered when the liquid level or pressure reaches certain values.
Then the liquid level in your sealed tank will rise. Repair the pump according to the actual situation or close the outlet of the seal tank.