HomeOIL WATER SEPARATORHigh PPM readings and measuring cell accuracy

High PPM readings and measuring cell accuracy

If PPM readings are consistently high, The cell may require cleaning.

Cleaning the cell is a simple process that requires only a bottle brush and a mild acid such as orange juice, vinegar or cola. These acids are preferred as they are safe to both the operator and the equipment. All power, air, sample and fresh water must be isolated prior to cleaning the measuring cell.

You must also ensure that your sample isn’t actually too dirty for the system to handle. This can often be experienced when the vessel is in high seas as the slop can not separate naturally due to the churning motion of the vessel.

First, the system must be drained of all water. This can be achieved by opening  the system-drain valve located at the bottom of the VPC and removing the Autoclean assembly from the top of the measuring cell, both highlighted green below;

The pipework at the inlet and outlet of the measuring cell must then be removed, ensuring that all parts removed are kept safe. These parts are highlighted in green below.

High PPM readings and measuring cell accuracy
High PPM readings and measuring cell accuracy

Plug the inlet and outlet of the measuring cell. This can be performed using a small rubber bung or alternatively, refit the pipe highlighted green in an upright position.

High PPM readings and measuring cell accuracy
High PPM readings and measuring cell accuracy

The measuring cell can now be filled with a mild acid such as orange juice, vinegar, cola or the Rivertrace cleaning kit. This is safe to both the operator and the equipment. This should be left for a minimum of 12 hours before cleaning the inside of the glass tube with a soft bottle brush. The measuring cell cover should never be opened to prevent irreparable damage and void of warranty.

Cover removed for illustration purposes. Never remove the cover onboard the vessel

High PPM readings and measuring cell accuracy
High PPM readings and measuring cell accuracy

Once the cell is cleaned with a soft bottle brush, refit all pipework and Autoclean. Please note that the Autoclean should not be fitted too tightly. This should be screwed in by hand fully and then backed out by 1/2 to 1 full turn.

Now flush with fresh water for around 15 minutes. This will flush the measuring cell and also properly flush the fresh water supply line to the ODME system which are prone to corrosion / debris build-up through sporadic usage. Once flushed, locate the “Check PPM ” setting from the service menu and ensure the PPM has decreased to a suitable level of 0ppm.

If the PPM reading remains high, a “Reset” of the measuring cell may be required.

Calibration Verification

If you have a satisfactory fresh water reading during these tests and you wish to verify the accuracy of your measuring cell, Rivertrace can provide a “Calibration Check” kit. The check kit is designed to be poured into the measuring cell and will cause a reading of 500ppm +/-10%. The kit is supplied complete with a procedure for crew to perform however we are more than happy to have our trained engineers attend your vessel to carryout the procedure. We will also provide a “Calibration Check” certificate to leave a paper trail of you measuring cells accuracy.

Measuring cell stuck at 1000ppm after performing standard fault finding steps.

This article explains how to reset the measuring cell if standard methods of clearing a constant 1000ppm reading are unsuccessful.

If the above methods are unsuccessful in clearing the 1000ppm fault, please proceed with the following steps :

      1. Disconnect J26 from the rear of the ODME Computer module and ensure that the valves cannot be opened during this process.
      2. Ensure that all supplied are available to the ODME system.
      3. In the “General Settings” menu, record all settings.
      4. Change the following settings to the values stated below :Flow Meter 1 :         Manual
        Manual Cap1 :         100 m3/hr
        Ship Speed :           Manual
        Man. Speed :          10 kn
        Cleanpr.Min :           0.0 Bar
        Cleanpr.Max :          6.0 Bar
        Workpr.Min :            0.0 Bar
        Workpr.Max :           2.0 Bar
      5. Save and exit.
      6. Once the settings are saved, enter the “Oil Discharge” mode and enter the following oil discharge settings :
        Flowmeter :             Cargo
        Oil type :                 9
        Oildisc acc:              0 L
        Alarm limit:             100 L
        Date:                      dd:mm:yy
        Time:                     hh:mm:ss

    Warning :               0 L/nm

        1. Start Oil Discharge
        2. Once “Start oil discharge” is selected, a preparation cycle will run. Once the preparation cycle is complete and the discharge screen is displayed, stop the discharge by pressing the enter button.
        3. Reset all settings to the original values recorded in step 2 and reconnect J26 at the rear of the ODME computer module.
        4. Retest the system.

    This procedure is a “Last resort”. If this procedure does not clear the 1000ppm reading, the measuring cell will need replacing. 

    Read more :

      1. Functionality of the Smart PFM107 oil in water analyser
      2. Smart ODME measuring cell replacement
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