Baltimore County, Md,. is in the process of upgrading its sewerage lift stations to ensure they remain operational during flood events. The county replaced conventional pumps with dry-wet submersible pumps. During a flood event, these pumps can operate continuously even when submerged under 40 ft of water.
As a part of this modernization program, Baltimore County officials wanted to automate the pump monitoring function. Instead of having to routinely send someone out to monitor discharge pressure gauges, the county wanted the pump condition to be transmitted electronically to a central monitoring station. The problem was that the existing mechanical gauges with diaphragm seals were virtually useless. Diaphragm seals that were supposed to protect the gauges invariably became impacted with suspended solids, and the gauge pointer was frozen in place. Routine flushing proved wholly inadequate to keep these gauges functional, as the diaphragm would clog within a few hours of flushing.
The county replaced the diaphragm seals with Onyx isolator rings. These rubber-lined isolator rings are easily installed between standard pipe flanges and provide an unobstructed flow path with no stagnation zones that can clog or plug. Clean instrument oil inside the isolator ring transmits process pressure to the gauge and transmitter. Onyx fitted these rings with pressure-balanced gauges designed for continuous submerged operation combined with submersible transmitters. During a recent storm event, several of these pump stations flooded, but Onyx isolator rings continuously transmitted accurate pressure signals, even while submerged under 40 ft of water for several weeks.