Quantitative Filter Papers, Grade 74 (Ashless)

This grade has medium flow rate and good particle retention and is the most commonly used acidwashed filter. Grade 74 covers a wide range of general ashless filtration applications. It is used for gravimetric analysis of numerous components (e.g.: cements, copper, clay, bismuth, silicon, iron) found in heavy industries such as construction, mining or steel. Ahlstrom 74 is also used as a high purity filter for speedy filtering of trace elements such as silver chromate, lead sulfate, zinc and ammonium hydroxides. Ahlstrom 74 is also found in general soil analysis for separating solid from aqueous extracts.

During sample preparation, the liquid may be filtered through a medium-porosity paper, such as Grade 74, to suppress ionization.

During the separation process of the partition methods, the sample is filtered through Grade 74. This grade is also used in the Soxhlet method to collect the oil and grease prior to extraction.

This precipitate is larger and requires a medium retention, medium flow ashless grade. Grade 74 is the recommended media.

Grade 74 is used during the initial extraction and to determine the percent of pyritic sulfur. Grade 54 and Grade 94 are used to determine the percent of sulfate sulfur.

The amount of humic acid present in coal correlates to the degree of oxidation. Because of the high solids loading, and presence of fines, the test recommends using a bi-layer filter. Grade 74 is used as the pre-filter and Grade 94 as the main filter. This will provide the necessary filtration and ash properties needed for the procedure.

Hydraulic Cement is tested for the presence of multiple elements with this procedure. Quantitative filters, Type II ASTM 832 E, F and G (Grades 54, 74, and 94 respectively) are recommended for various steps in the process.

The moisture equivalent and porosity is used to give an estimate on aquifer storage coefficient. A dry sample of soil is placed in a gooch crucible that is lined with Grade 74, which is then placed in a water bath till the soil reaches stable saturation. The paper works as both a wick and barrier.

The salt concentration of the water in the soil is tested with this method. The sample is placed in a press with Grade 74. The sample is compressed