(a) Tests required in §§162.050-23 and 162.050-35 must be performed using the following three types of test fluids:

(1) Test Fluid A, which is a marine residual fuel oil in accordance with ISO 8217 (incorporated by reference, see §162.050-4), type RMG 380 (density at 15 °C not less than 980 kg/m3);

(2) Test Fluid B which is a marine distillate fuel oil in accordance with ISO 8217, type DMA (density at 15 °C not less than 830 kg/m3);

(3) Test Fluid C must be a mixture of an oil-in-fresh water emulsion, where 1 kg of the mixture consists of:

(i) 947.8 g of fresh water;

(ii) 25.0 g of Test Fluid A;

(iii) 25.0 g of Test Fluid B;

(iv) 0.5 g of surfactant (sodium salt of dodecylbenzene sulfonic acid) in the dry form; and

(v) 1.7 g of iron oxides, a black ferrosoferric oxide (Fe3O4) with a particle size distribution of which 90 percent is less than 10 microns, the remainder having a maximum particle size of 100 microns.

(b) Test Fluid C must be prepared as needed for §162.050-23 or §162.050-35 by using the following procedures:

(1) Measure out 1.2 times the quantity of surfactant required from the WORKSHEET FOR DETERMINING CONSTITUENTS OF TEST FLUID C, see figure 162.050-20;

(2) Mix it with fresh water and stir well in a small container to make a mixture until the surfactant has been thoroughly dissolved, but use no more than the minimum amount of water necessary to make a complete solution;

(3) Fill clean test fluid tank with fresh water with a quantity 1.2 times the volume of the total quantity of water in Test Fluid C needed for the test described in §§162.050-23 and 162.050-35;

(4) Operate the centrifugal pump B running at a speed of not less than 3,000 rpm with a flow rate at which the volume of the test fluid has been changed out at least once per minute;

(5) Add the surfactant mixture from paragraph (b)(2) of this section first, followed by oil and suspended solids (iron oxides) respectively, both 1.2 times of the required amounts, to the fresh water in the tank;

(6) To establish a stable emulsion keep running the centrifugal pump B for one hour and confirm no oil floats on the surface of the test fluid; and

(7) After the one hour stated in paragraph (b)(6) of this section, keep running the centrifugal pump B at reduced speed to approximately 10 percent of original flow rate, until the end of the test.

FIGURE 162.050-20

[USCG-2004-18939, 74 FR 3385, Jan. 16, 2009]