The engine manufacturer for the main engines used on your harbor tug specifies a supplemental coolant additive consisting of molybdate and nitrite be used to supplement the heavy-duty antifreeze for the closed, re-circulating freshwater cooling system. A test-strip comparison chart as shown in the illustration is used for coolant testing purposes. If the molybdate concentration color corresponds to row 2 and the nitrite concentration color corresponds to column B, what statement is true? Illustration MO-0211
• How to read a test strip comparison chart by matching the color row and column • Meaning of the green SERVICE zone versus areas outside it on the SCA (supplemental coolant additive) grid • Relationship between molybdate/nitrite levels and whether you must add SCA, drain coolant, or make no change
• When the molybdate color matches Row 2 and the nitrite color matches Column B, what SCA units-per-gallon value do you get at that intersection? • Is that intersection square inside the green SERVICE area, the lower "PRE‑CHARGE" area, or toward the upper "TEST" area of the chart? • If a reading falls in the green SERVICE area on this type of coolant chart, what does that usually indicate about whether adjustment is needed?
• Locate Row 2 on the molybdate (vertical) scale and Column B on the nitrite (horizontal) scale and find the exact intersection box. • Confirm the color of that box (is it green or another color?) and any label (PRE‑CHARGE, SERVICE, TEST) covering that region. • Match that zone’s meaning with the answer choice that best describes whether levels are too low, too high, or within acceptable limits.
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