All ships, particularly container vessels, need to discharge water primarily for managing ballast, which is crucial for the ship’s stability, manoeuvrability, and structural integrity. Before discharging this water back into the ocean, it’s crucial to ensure that it does not contain oil or other contaminants. 

Given the potential ecological impact, the discharge of ballast water is strictly regulated globally, mandating that the water must contain less than 15 parts per million of oil to comply with international standards. Rivertrace has designed a range of Oil Discharge Monitoring Equipment (ODME) to provide means of monitoring, recording and controlling this process. 

To ensure accurate measurements of oil content in water their Smart ODME systems require precise calibration. This calibration process involves several components and steps, focusing primarily on ensuring the measuring cell (of which there are 8) and the flow rate sensors are accurately calibrated to measure oil content and discharge rate, respectively. 

Historically, this was a very time-consuming and manual process, taking on average two days to calibrate a single system. It was our job to streamline this task.

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To detect the level of oil content within clean water, the Smart ODME system relies on proprietary “Smart Cell” Detector Array Technology. This system projects a precisely controlled beam of light through a water sample contained in a vial. The light beam’s interaction with the water is captured by a curved array of light sensors. The principle here is that clean water directs the light beam to a single sensor, indicating minimal refraction. In contrast, water contaminated with oil causes a broader refraction of light, dispersing it across multiple sensors. So, having accurate control over both the flow of water and oil in the system is crucial to the calibration process.

Central to our automated calibration system was the integration of a Kunbus RevPi industrial PC, with additional input/output modules. This setup enables the integration of a programmable injection pump and a proportional valve into the existing system, accompanied by flow and pressure sensors. This allowed us to precisely regulate water flow and oil injection rates, ensuring that the calibration process is both accurate and repeatable.

In addition, the Kunbus unit enables direct communication with the cells, allowing for the acquisition of light sensor readings.

Utilising the data gathered, we could then proceed to generate a calibration curve. This curve enabled us to calculate the concentration of oil in parts per million (ppm) based on the sensor array’s response. The calibration curve essentially translates the light sensors’ readings into a quantifiable measure of oil content, which we can then write back to the cell as a calibration value.

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What was once a long and complicated process, requiring highly skilled staff, is now almost completely automated, with only a few simple manual tasks remaining. 

As a result, the calibration process, which used to take a day, now only takes 30 minutes and frees up staff to concentrate on other areas of the business. This efficiency gain not only accelerates the process but also allows staff members to redirect their focus towards other strategic aspects of the business.