A suburban township in the upper Midwest United States buys their drinking water from a major municipal water district. The township’s water distribution system network has four connections to the larger municipality’s water transmission main. The municipality has many wholesale customers and has implemented contracts with each customer to limit the peak flows and the time of day in which they may occur. If a customer exceeds the limit, they are assessed significant surcharges.   
These potential surcharges make it essential for wholesale customers to manage water demand prudently. As a result, many customers invest in solutions to minimize usage peaks and control what time of day they occur, including elevated water storage towers and control valves at each connection to the transmission main.  
The major municipal water district owns and operates “metering pits” with electromagnetic flow meters (magmeters) immediately upstream of the control valves owned by each customer. However, as a rule, the signals from these meters are not made available to any customers on a real-time basis. Wholesale water customers are only provided with datalog summary reports from these meters on a routine schedule for billing purposes. Without a method of measuring flow or receiving timely flow rate data from the water district, the suburban township had no means of knowing, in real time, the amount of water they were drawing from the transmission main. Therefore, they did not know if or when they were exceeding the contractual peak flowrate limits and incurring significant surcharges from the water district until they were billed.

The township needed to determine the flowrate at each of its four connections to the transmission main so that they could control how much was being drawn at each site. They also needed to know the total flow from the municipality’s transmission main so that they would not exceed their contractual peak demand.

The control valves were initially installed without flow meters. The intention was to use valve position and upstream/downstream (differential) pressure readings to estimate the flow using the characteristic curve of the valve. However, this proved to be too complicated and cumbersome for the township‘s SCADA system to implement effectively.

The local Siemens representative worked with the township and their engineer to find a solution to measure the flow rate and totalize the volume of flow at each of the customer’s control valve sites. The most significant challenge was the piping configuration, as all of the valves were previously installed without proper spacing for a flow meter. The Siemens representative used a Siemens clamp-on ultrasonic flow meter (SITRANS FS230) to demonstrate the technology to the customer and prove that it would reliably meet their objectives.   
The valve with the worst piping configuration was selected for the demonstration, with the assumption that if the flow meter would work for the worst site, it would work at the other three sites as well. If the Siemens flow meter did not work for that site, the township would need to consider alternate and more costly flow measurement technologies.   
Within minutes of arriving on site, the meter was installed and providing reliable readings. The unit was allowed to log for a period of three days. After that, the data was retrieved and compared to the readings from a competitive magmeter in the municipal water provider’s metering pit. The logger on the Siemens clamp-on flow meter helped establish and solidify the confidence of the owner and the engineer that the meter would work for these applications.