Application Corner: Sewage district installs new flowmeters

Feb. 1, 2023
New flowmeters were installed to measure the same sewage as its respective billing flowmeter so their measurements could then be compared and used to quantify measurement error.

Previous articles described the sewage collection systems for two adjacent sewage districts where the flow measurements used to allocate expenses and bill one of the sewage districts flowmeters was questioned in court. As a legal matter, the court decided that my testimony did not reveal that anything had changed with regard to the flowmeters so the second sewage district was not instructed to correct their deficiencies. In other words, the court allowed the second sewage district to knowingly overbill the first sewage district.

The disappointing court ruling prompted me to recommend that the first sewage district install a superior flowmeter in each of the forced mains located immediately upstream of each of two billing flowmeters. Therefore, each new flowmeter was installed to measure the same sewage as its respective billing flowmeter so their measurements could then be compared and used to quantify measurement error. Money was tight but the first sewage district installed these two flowmeters.

Measurements from one of the billing flowmeters showed that the billed flow was approximately 50% higher than the measurements obtained by the new superior flowmeter. I remember that the other billing flowmeter measured higher (perhaps 20% to 30%) than its respective superior flowmeter. Further, these errors had been occurring for years, so the first sewage district had clearly been overbilled for years.

Despite these superior measurements of the same sewage streams, attempts made to have the sewage flowmeters fixed fell on deaf ears at the second sewage district, which would not correct the flowmeter installations nor change calibration techniques. The judge had ruled that they did not have to change anything, so they did nothing and therefore knowingly continued to overbill.

Up next: More about fixing one of these flowmeters.

David W. Spitzer has written over 500 technical articles and 10 books on flow measurement, instrumentation, process control and variable speed drives. David offers consulting services, writes/edits white papers, presents seminars and provides expert witness services at Spitzer and Boyes LLC (spitzerandboyes.com or +1.845.623.1830). 

Sponsored Recommendations

Learn About: Micro Motion™ 4700 Config I/O Coriolis Transmitter

An Advanced Transmitter that Expands Connectivity

Micro Motion 4700 Coriolis Configurable Inputs and Outputs Transmitter

The Micro Motion 4700 Coriolis Transmitter offers a compact C1D1 (Zone 1) housing. Bluetooth and Smart Meter Verification are available.

Keys to Improving Safety in Chemical Processes

Many facilities handledangerous processes and products on a daily basis. Keeping everything undercontrol demands well-trained people workingwith the best equipment.

Micro Motion™ G-Series Coriolis Flow and Density Meter

Micro Motion G-Series: market-leading compact design featuring advanced process diagnostic capability.