Dear Queseans,
in the last couple of months, two topics concerning the sampling line of the OWS emerged from PSC inspections which led to some interesting publications from Class societies:
#Subject 1
The OWS does not stop or does not re-direct the effluent via the 3-way valve from ovb’d to the bilge holding tank, when the sampling line is closed/blocked.
There were some reports that the above scenario, concerned only some systems manufactured by JOWA, truth is we have seen a similar behavior also with systems from major Japanese vendors equipped with the Bilgemon488 but supplied without a pressure switch in the ppm unit.
In case the sampling piping is equipped with a valve, it is suggested this valve to be removed or to be sealed in the open position (and same to be written in the oil record book).
#Subject 2
The sampling point on the ovb’d line is not located in a vertical section of the piping and/or it is located far from the equipment outlet.
This one has to do with the assumption that the sample taken, may not be representative if the sample point is in a horizontal position, as due to the density difference of oil & water, the effluent stream driven to the ppm unit may consists only of water.
For more information please refer to the attached publications from ABS & DNV.
Remember that for any modifications on the OWS piping, you should have the confirmation from Class first.
ABS Regulatory News - Letter to Industry OWS Issues and Flow Switch.pdf (440.0 KB)
DNV_TecRegNews_No_15_2023.pdf (280.1 KB)