This document describes a methodology for establishing quantitative performance data for oil skimmers, so the end user can objectively judge, compare and evaluate the design and performance of different skimmers. The methodology applies to testing in a basin and requires control of oil properties and oil slick characteristics.

　

The method is applicable to all types of skimmers provided that the equipment dimensions are within the physical limitations of the test basin. The test procedure provides full-scale test results for the unit tested, under controlled conditions, and for one or more classes of oil. Care should be taken when applying the test results to predict skimmer performance under field conditions.

　

The following normative documents contain provisions, which, through reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards.

　

ISO 16165, Ships and marine technology - Marine environment protection - Terminology relating to oil spill response

　

For the purposes of this International Standard, the terms and definitions given in ISO 16165 and the following apply.

　

the period of time within the steady state period when recovered fluid is collected for establishing performance data.

　

solid or semi-solid substance that could interfere with the operation of a spill control system

　

amount of water emulsified into the oil as a result of the skimming/pumping process (not including water originally in the test fluid), expressed as a decimal fraction between 0 and 1

　

total volume of fluid recovered per unit time (m3/h)

　

ratio of test fluid (oil or emulsion) recovered to the total volume of fluid recovered; expressed as a percentage

　

volume of test fluid (oil or emulsion) recovered per unit time (m3/h)

　

oil that is water-free or incorporates emulsified or encapsulated water that does not readily separate out

　

unit designed to remove oil from the water surface

　

average distance from the boom apex to the leading edge of the slick

　

upstream end of the slick-the location where inflowing oil encounters the accumulated slick

　

period of time during which the test conditions and operating parameters are constant or within acceptable variability ranges

　

This Standard is applicable to any test arrangement that allows for the control and monitoring of the test conditions.

　

The test facility should be designed and equipped to control the following parameters:

Throughout testing, there must be sufficient clearance between the skimmer and the tank walls and any containment device, so as not to restrict oil flow to the skimmer or otherwise impede normal operation of the unit.

　

Since the necessary clearance varies with oil viscosity and unit recovery rate, adequate oil flow should be demonstrated in each specific case, through oil flow observations or slick thickness measurements. The total width of the skimmer (including floats) should not exceed 50% of the tank width if oil flow is required to the downstream side of the skimmer. Clearance between the unit and the tank floor should be no less than 50% of the draft of the skimmer.

　

Testing shall establish quantitative performance data for the unit as a function of the following parameters:

Testing is to be carried out with oils meeting the specifications shown in Table 1.

　

To minimize problems associated with flow characteristics of waxy oils, testing should be carried out at water temperatures at least 5℃ above the pour point of the test oil.

　

Oil and emulsion viscosity must be reported at shear rates 1, 10 and 100 s-1. At least two of these must be based on measurements, while the third may be determined by extrapolation.

　

In this Standard, oil is categorized as non-emulsified (fresh) even if it contains up to 20% water. Such oil may be used for testing as a "water-free" oil provided that the viscosity is within the ranges specified in Table 1. Note that even a small water content may lead to significant viscosity increase and should be compensated by dilution with a lighter oil fraction.

　

All oils and emulsions may be reused provided that the properties of the test fluids remain within the ranges defined in Table 1.

　

　

For each specific test oil, the slick thickness must be maintained within the ranges defined in Table 1. Thickness should be measured at a location 1.5 m from the skimmer entrance. Appendix 1 provides guidance for combining oil volumes and current speed in order to achieve the desired slick thickness when conducting tests in tow or flume tanks.

　

The oil slick thickness must be monitored regularly throughout the testing period and any deviations from the desired slick thickness should be documented. Tests should be rejected if the time averaged slick thickness deviates more than 10% from the specification in Table 1.

　

There are a number of operating parameters that may affect the skimmer performance. These can include adhesion surface speed, inclination angles, pump flow rates, skimmer draft, and weir depth. From these parameters the main operating parameter should be identified. Testing should as a minimum include three variations of the main operating parameter, preferably to include one above and one below the optimum setting.

　

Testing must be carried out to assess the skimmer's ability to operate in the presence of various forms of debris in the oil slick. This examination will be qualitative in nature and is intended to provide the end user with a general indication of the effects of different materials that are often found in oil spill recovery situations. Of particular interest would be the debris' effects on oil intake, essential mechanical elements of the unit (e.g. scrapers, wringers, pumps), and overall processing of the recovered oil.

　

The following groups of materials are to be introduced into the oil slick individually; their impacts observed and reported; and then cleared from the testing area before the next group is introduced.

　

Ropes

　

Two 1.0 m × 25 mm diameter polypropylene rope;

Two 1.0 m × 8 mm diameter polypropylene rope;

Four 0.6 m × 77 mm diameter polypropylene rope

　

Soft wood pieces

　

One board 1 meter × 50 mm × 100 mm;

Ten blocks 10mm × 25mm × 40 mm)

　

Loose granular materials

　

Five litres shredded wood bark or wood shavings

　

Plastic containers

　

Four 0.5 litre soft drink bottles;

Two 3.0 litre plastic tubs

　

Plastic bags

　

Four supermarket bags (approximately 300 mm × 300 mm);

Two large domestic garbage bags (approx 500 mm × 1000 mm)