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. "..~ ct 7.1.1.4 Assemble filter holder and filter following the • manufacturer's instructions. Place the filter on the support sr.reen and sec~lre. 1.1.1.5 '~2igh c::c a subsac,pla of the waste (i00 gram minfmum) and re+~•d the weight. 7.1.1.6 Ailpsv slurries to stand to permit the solid phase to settle. Samples tRet settle slowly may be centrifuged prior to filtration. Centrifugation is to be used only as an aid to filtration. If used, the liquid should be decanted and filtered followed by filtration of the solid portion of the waste through the same filtration system. 1.1.1.7 Quantitatively transfer the sample to the filter holder (liquid and solid phases). Spread the sample evenly over the surface of the filter. If filtration of the waste at 4'C reduces the amount of expressed liquid over what would be expressed at room temperature, then allow the sample to warm up to room temperature in the device before filtering. NOTE: If sample material (>1 Y. of original sample weight) has obviously adhered to the container used to transfer the sample to the filtration apparatus, determine the weight of this residue and subtract it from the sample weight determined in Step 7.2.1.5 to determine the weight of the sample that will be filtered. Gradually apply vacuum or gentle pressure of 1-ZO psi, until air or pressurizing gas moves through the filter. If this point is not reached under ]0 psi, and if no additional Tiquid has passed through the filter in any 2-minute interval, slowly increase the pressure in 10 psi increments to a maximum of 50 psi. After eacfi incremental increase of 10 psi, if the pressurizing gas has not moved through the filter, and if no additional liquid has passed through the filter fn any 2-minute interval, proceed to the next l0-psi increment. When the pressurizing gas begins to move through the filter, or when liquid flow has ceased at 50 psi (t.~., filtration do?s not result in any additional filtrate within any 2-minute period}, stop the filtration. NOTE: Instantaneous application of high pressure can degrade the glass fiber filter and may cause premature plugging. ).1.1.8 The material in the filter holder is defined as the solid phase of the sample, and [he filtrate is defined as [he liquid phase. NOTE: Some samples, such as oily wastes and some paint wastes, will obviously contain some material that appears to be a liquid, but even after applying vacuum or pressure filtration, as outlined in Step 7.].1.7, this material may not filter. If this is the case, the material within the filtration device is defined as a solid. Do not replace the original filter with a fresh filter under any circumstances. Use only one filter. 1312 - 1 Revision 0 November 1992