Flow Measurement for a Reverse Osmosis Plant in Peru

Project at a Glance

The Challenge

A water-treatment engineering company in Peru needed reliable flow measurement on the main permeate pipelines of a reverse osmosis system. The application covered four pipe sizes - from DN25 to DN150 - and flow rates from 0.88 m³/h to 320 m³/h. The meters therefore had to combine stable low-flow performance with sufficient capacity for the largest line.

The central technical concern was the low conductivity of RO product water. Because electromagnetic flowmeters depend on the conductivity of the medium, the customer needed confirmation that the selected instruments would provide continuous signals without interruptions or excessive fluctuation. Stable communication with the PLC was equally important, since signal loss could affect system control and overall RO-plant availability.

Supmea's Solution

Supmea evaluated the product-water conductivity, pipe dimensions and required measuring ranges before recommending three SUP-LDG units and one SUP-FMC400 electromagnetic flowmeter. Each meter was sized for its corresponding pipeline, with measuring ranges of 0.88-8.8 m³/h, 3.5-35 m³/h, 6-60 m³/h and 32-320 m³/h.

The instruments were configured with PTFE liners, IP65 protection and both 4-20 mA and RS485 outputs. This configuration supported outdoor installation and provided two practical signal options for integration with the existing PLC and monitoring architecture.

Delivery and Project Support

• Conductivity and application review before final instrument selection.
• Remote installation guidance for the four pipeline measurement points.
• Door-to-door delivery and expedited processing to support the project schedule.

Measured Results

Customer feedback after installation confirmed stable performance under the plant's operating conditions:

• At a conductivity of 150 μS/cm, the flow signal remained continuous and uninterrupted, with a reported data fluctuation rate below 0.5%.
• Measurement performance met the specified accuracy of ±0.5%.
• The PLC received the instrument signals successfully, with a reported reception rate of 100% and no signal-loss events causing control malfunctions.
• The instruments continued to operate normally as product-water conductivity varied across the expected range of 5-200 μS/cm.

Business Value

The completed installation gives the RO plant reliable flow visibility across both small and large permeate lines. Stable measurement in low-conductivity water reduces the risk of data gaps, while dependable PLC communication supports continuous process control. By matching each meter to the actual pipe size and flow range, the solution also provides a scalable measurement foundation for day-to-day operation of the treatment system.

“The instruments have now been installed in a reverse osmosis plant.”