Tough challenges for sewer lift station level measurement are operating in an extremely harsh environment; and reliable performance without frequent maintenance. Pump controls are dependent on accurate level sensing; so the level sensor must be designed to withstand these conditions; without the need for constant maintenance and calibration.
Lift stations present one of the most corrosive environments imaginable. The chemistry in the water and air quickly attack any equipment it finds. Instrumentation must be constructed of with corrosion resistant materials; such as high grade stainless steel. Anything less will not last; causing shortened life, downtime and, ultimately, a higher cost of ownership.
Marinated sewer tends to be more of a slurry, with solids, grease and debris that can clog traditional level sensors; requiring increased maintenance. Further, when placed in the areas of highest mixing, it can get in the way of the pumps, level floats and cables. The sensor must be placed out of the way, where debris accumulation tends to occur; so it needs protection to extend service intervals and improve performance.
Sensor drift is another challenge that affects level sensor performance and maintenance frequencies. Older technology, and cheaper analog models, require routine calibration to correct sensor drift. More advanced level transducers have an internal microprocessor on the board that store calibration data and greatly improve sensor performance over the long haul.
To gain higher level precision measurements, submersible transducers should be ‘vented’ to the atmosphere. Vented transducers have a vent tube within the cable. While vital to sensor performance, the vent must be protected against moisture; which can wick its way to the transducer and cause failure. Make sure to route the sensor cable to a dry and protected enclosure and install a moisture absorbing desiccant canister. The desiccant can be recharged or replaced; keeping the internal components dry and greatly extending the life of the transducer.
The Ametek 675 Submersible Level Sensor was specifically designed to perform in sewer lift stations. The sensor is constructed of extremely rugged 316L Stainless steel. It has an oversized 3.5” flush diaphragm with a large ‘shark cage’ to prevent clogging.
The vent tube is protected with a large desiccant canister to absorb moisture. The desiccant turns color to indicate when service is required.
0.25% Full Scale Accuracy is maintained by an ion implanted silicon semiconductor chip on its board.
The units are also available with AC or DC Surge and Lightning protection.