Reverse Osmosis Filter Monitoring


Reverse osmosis (RO) process technology is deployed in many industries. This process uses membrane separation which is one of the most economical means to remove suspended solids from feed water. Listed below are examples of some typical RO applications:

  • Pretreatment for deionizers for ultra pure water, typically used in the semiconductor industry
  • Production of zero-hardness water used for boiler feed water
  • Treatment of sanitary waste
  • Water purification

The RO function is accomplished by differential pressure across an array of filters. High pressure is applied to the raw water side of the filter that creates sufficient differential pressure across the filter enabling flow of the filtered water to the low-pressure side of the system.

Plant with Filter arrays and Storage tank


Expected benefits

  • Accurate differential pressure measurement is key to filtered water quality.
  • Transmitter range flexibility reducing inventory with fewer models required for RO system designs.
  • Robust Transmitter design delivering stable output under demanding process conditions.
EJA110E Differential Pressure Transmitters


In this semiconductor factory they produce their own deionized water. A cellulose acetate membrane removes dissolved solids from the filtered raw water. Differential pressure values are the key factor determining filter maintenance intervention for cleaning or replacement of filter components.

Application requirements:

  • Pressure transmitter must have accurate measurement.
  • Pressure transmitter able to withstand plant vibration with more reliable performance than Pressure switches traditionally used.
  • Pressure transmitter to deliver long term stability regardless of harsh process conditions of pressure surges and fluctuations that caused zero-point shift and drift with other transmitter brand’s previously used on site.
  • Reduce maintenance activities and costs where possible.



EJA110E medium range unit was chosen to cover the measurement range 0 to 30 kPa (0 to 120 inH2O). The client focused on 0.055 % accuracy of capsule span, superior long-term stability (≤± 0.1 % @ 16 MPa, 2300 psi) and vibration tolerance.

Static pressure transient test data

【Static pressure transient test data】
Model: EJA110E M capsule with set range -2 to 2 kPa
Applied static pressure change: 500 kPa in 0.1 Sec

With sudden static pressure changes, the output from EJA110E responds stably and keeps zero every time.



DPharp EJA110E exhibits exceptional stability. Trial results from an EJA110E on this RO process that was evaluated over 6 months presented no zero drift or shift. Maintenance crews were relieved with no maintenance intervention or action required during the evaluation period. The EJA110E consistently delivers accurate and stable measurement of process conditions under real world conditions, resulting in better process efficiency and less maintenance downtime.

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  • Water & Wastewater

    Water resources are finite, and therefore contributing to a sustainable water cycle is one of the Sustainable Development Goals (SDGs). Yokogawa has been providing advanced digital control solutions for the stable supply of clean and safe water, wastewater treatment for protecting the water environment, water loss management and optimization of plant operation for reducing CO2 emissions and running costs. With our leading-edge technologies, dependable products and extensive expertise and experience of diverse water projects around the world, we work with you to provide sustainable water solutions that boost your business and add value throughout the plant lifecycle.

    Yokogawa supports a wide range of water control applications in both the municipal and industrial water markets.



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