Standards Development

Scope

This standard specifies methods for calibration of the instruments measuring the concentrations of polycyclic aromatic hydrocarbons (PAHs) contained in discharge water from exhaust gas cleaning systems (EGCS) equipped on ships and also provides the specifications of test samples used for calibrating the instruments. The standard further specifies the PAH species to be measured for calibration.

Purpose

The marine exhaust gas cleaning systems (EGCS) currently installed base is some 4,000 ships. This is expected to grow to 10,000 installed ships during the next 10 years and may even reach 50,000 ships to meet further air quality requirements demanded by IMO. Wet EGCS uses sea water as the gas scrubbing medium. The process also “scrubs” out oil and other hydrocarbons. The IMO limit the concentration of oil in the discharge water under the Guidelines for Exhaust Gas Cleaning Systems (Resolution MEPC.259(68)). At present there is no standard with which to assess the measurement of the PAH concentrations in the water discharge.

Sample analysis programmes (MEPC 73/INF.5) indicate the profile of PAH species in EGCS discharges is petrogenic i.e. typical of petroleum and un-combusted fuel oil. Instruments calibrated using a PAH mix, typical of a fuel oil, will therefore enable the quantity of oil entering the sea to be closely monitored and controlled – a requirement of the EGCS Guidelines.

The wavelengths of light which are absorbed by phenanthrene have the profile of a sharp peak, which ultimately results in the inconsistent reporting of overall PAH concentrations in real-world EGCS discharges by different configurations of the instrument. The smooth profile of a PAH mixture will significantly reduce this inconsistency without the need for changes in existing instrument designs.

Although measured by PAH, instruments could readily report a concentration of oil; a parameter that is well-recognized and already used for the regulation of pollution from ships. It will also eliminate inconsistencies caused by different interpretations of phenanthrene equivalence.

The suppliers of EGCS must supply an instrument to monitor oil discharges. The instrument shall be approved by the vessel’s Flag State. The present situation is unsatisfactory as it is difficult to determine the effectiveness and consistency between different instruments. Providing an agreed set of calibration standards will enable instrument suppliers to calibrate and then certify their instruments irrespective of the measurement technology used within the instrument. The end user will be satisfied with the certainty over the consistency of the end result.

Consider the following: Is there a verified market need for the proposal? What problem does this standard solve? What value will the document bring to end-users? See Annex C of the ISO/IEC Directives part 1 for more information. See the following guidance on justification statements on ISO Connect:

https://connect.iso.org/pages/viewpage.action?pageId=27590861