Instrumentation Used on Mechanical Seals 1

[sjmgd977]

What types of instruments are used on mechanical seals used in pump systems? Are they worth the hassle of installing them and maintaining them?

I would assume that pressure(?) is the parameter we measure? If so, what are we taking the pressure across?

 

[JJPellin]

We use instruments to monitor a number of important parameters on our pumps. For pumps in services that have a high potential for fire, vapor cloud, environmental impact or personnel injury, we want to monitor for conditions that would indicate a leak. These pumps would usually have a dual seal either pressurized (API Plan 53) or unpressurized (API plan 52). For Plan 52, we monitor pressure in the seal reservoir. The vent to flare off of the top of the seal pot is orificed, so a build-up of pressure indicates a leakage from the primary seal out to the flare. For Plan 53, we monitor seal pot level since an external leak or an internal leak will result in a loss of level, but not necessarily any change in pressure. In our plant, API plans 11, 13, 62, 32, 21 or 23 would not usually have any instruments continuously monitoring for pressure, flow, temperature or level. For pumps with dry gas seals (Plan 74), we would usually monitor buffer gas pressure so that we would get an alarm on loss of gas pressure.

I based my comments on an assumption that you are referring only to instruments which are wired to provide trendable data to a PLC or DCS system or automatically alarm. Almost all seal systems use local instruments (pressure gauges, flow meters, thermometers) to provide information to the operators.


Johnny Pellin