ASTM D859 PDF

ASTM D95 - A number in parentheses indicates the year of last reapproval. A superscript epsilon e indicates an editorial change since the last revision or reapproval. This standard has been approved for use by agencies of the Department of Defense. Scope 1. It is applicable to most waters, but some waters may require?

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Historical Version s - view previous versions of standard. More D It is found as the oxide in crystalline forms, as in quartz; combined with other oxides and metals in a variety of silicates; and in amorphous forms.

Silicon is the most abundant element in igneous rocks and is the characteristic element of all important rocks except the carbonates. It is the skeletal material of diatoms but is not known to play a significant role in the structure of processes of higher life forms.

The presence of most silica in natural waters comes from the gradual degradation of silica-containing minerals. The type and composition of the silica-containing minerals in contact with the water and the pH of the water are the primary factors controlling both the solubility and the form of silica in the resulting solution.

Silica may exist in suspended particles, as a colloid, or in solution. It may be monomeric or polymeric. In solution it can exist as silicic acid or silicate ion, depending upon pH. Under certain conditions, silica forms troublesome silica and silicate scales, particularly on high-pressure steam turbine blades. In cooling water systems, silica forms deposits when solubility limits are exceeded. In contrast, silica may be added as a treatment chemical in some systems, for example, in corrosion control.

Silica removal is commonly accomplished by ion exchange, distillation, reverse osmosis, or by precipitation, usually with magnesium compounds in a hot or cold lime softening process.

It is applicable to most waters, but some waters may require filtration and dilution to remove interferences from color and turbidity. Due to the complexity of silica chemistry, the form of silica measured is defined by the analytical method as molybdate-reactive silica. Those forms of silica that are molybdate-reactive include dissolved simple silicates, monomeric silica and silicic acid, and an undetermined fraction of polymeric silica.

It is particularly applicable to treated industrial waters. It may be applied to natural waters and wastewaters following filtration or dilution, or both. For seawater or brines, this test method is applicable only if matched matrix standards or standard addition techniques are employed. No other units of measurement are included in this standard.

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. This is acceptable when, as frequently occurs, the molybdate-reactive silica is in the milligram per litre concentration range while the nonmolybdate-reactive silica, if present at all, is in the microgram per litre concentration range. Refer to Appendix X1 for historical information.

Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard.

Scope 1. Link to Active This link will always route to the current Active version of the standard.

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ASTM D859-16

Historical Version s - view previous versions of standard. More D It is found as the oxide in crystalline forms, as in quartz; combined with other oxides and metals in a variety of silicates; and in amorphous forms. Silicon is the most abundant element in igneous rocks and is the characteristic element of all important rocks except the carbonates. It is the skeletal material of diatoms but is not known to play a significant role in the structure of processes of higher life forms. The presence of most silica in natural waters comes from the gradual degradation of silica-containing minerals. The type and composition of the silica-containing minerals in contact with the water and the pH of the water are the primary factors controlling both the solubility and the form of silica in the resulting solution.

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Standard Test Method for Silica in Water

Active view current version of standard. Other Historical Standards. More D It is applicable to most waters, but some waters may require filtration and dilution to remove interferences from color and turbidity.

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