Crude petroleum contains sulfur compounds, most of which are removed during refining. However, of the sulfur compounds remaining in the petroleum product, some can have a corroding action on various metals and this corrosivity is not related to the total sulfur content. In addition, fuels can become contaminated by corrosive sulfur compounds during storage and distribution. The corrosive effect can vary according to the chemical types of sulfur compounds present.
The silver strip corrosion test is designed to assess the relative degree of corrosivity of a petroleum product towards silver and silver alloys.
Reactive sulfur compounds present in automotive spark-ignition engine fuels under some circumstances can corrode or tarnish silver alloy fuel gauge in-tank sender units (and silver-plated bearings in some 2-stroke cycle engines). To minimize or prevent the failure of silver alloy in-tank sender units by corrosion or tarnish, Specification D4814 requires that fuels shall pass the silver strip corrosion test.
1.1 This test method covers the determination of the corrosiveness to silver by automotive spark-ignition engine fuel, as defined by Specification D4814, or similar specifications in other jurisdictions, having a vapor pressure no greater than 124 kPa (18 psi) at 37.8°C (100°F), by one of two procedures. Procedure A involves the use of a pressure vessel, whereas Procedure B involves the use of a vented test tube.
1.2 The result of the test is based on a visual rating that is classified as an integer in the range from 0 to 4 as defined in Table 1.
1.3 The values stated in SI units are to be regarded as the standard. The values in parentheses are for information only.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific warning statements, see 6.1 and Section 7.
TABLE 1 Silver Strip Classifications
Note 18212;Classifications provided by IP 227 Determination of Corrosiveness to Silver of Aviation Turbine Fuels–Silver Strip Method.
Note 28212;Distinctions between Classifications 1 and 2 are made using The Color Standard for Tube Deposit Rating (referenced in Test Method D3241) in accordance with 11.1.1.
| Classification | Designation | Description |
|---|---|---|
| 0 | No tarnish | Identical to a freshly polished strip, but may have some very light loss of luster |
| 1 | Slight tarnish | Faint brown or white discoloration of strip (see 12.1) |
| 2 | Moderate tarnish | Peacock colors such as blue or mauve or medium/dark straw or brown coloration (see 12.1) |
| 3 |
ASTM D7671-10e1 history
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