Why does it matter which side of the membrane is used as the feed side? The update addresses a deficiency and in our opinion corrects an error that has existed since the standard was first released in Perhaps the most critical component of the SDI test is the membrane filter used in the test. Previous versions of the standard had defined the membrane as follows: 6. Use only filters that are packaged in the same orientation. Note that the type of membrane, that is, the polymer, was never specified.
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A number in parentheses indicates the year of last reapproval. Some filter holders include a foam support pad,which should be used. Place the filter grid side up. Handle themembrane filter only with dull tweezers to avoid puncturing. Avoid touching the membrane filter with the fingers. NOTE 1—Other membrane filter sizes, that is, 25 mm or 90 mmdiameter, can be used. Replace the top half of the filter holder and closeloosely. Closethe valve and tighten the filter holder.
Simultaneously, using a stopwatch,begin measuring the time required for the flow of mL. Record the time ti. Leave the valve open for continued flow. The nonplugging reference water can be obtained byfiltering distilled water through a 0. If a different filter size is used, adjust the sample size in direct proportionto the filter area. Measure the watertemperature and check the pressure as each sample is collected Note 7 and Note 8.
Precision and Bias The pooled single operator precision is 0. The test method is very sensitive to bothquantity and size of suspended particles, which contribute tothe plugging of the membrane filter. Maintenance of theintegrity of the samples cannot be guaranteed through prepa-ration of the bulk mix, subsampling for testing, shipping, andholding.
Moreover, approximately 5 gal of sample are requiredfor each SDI test run. Thus, if large stock solutions exhibitingdifferent SDI values could be prepared and if representative 30to gal subsamples could be drawn, shipping two or three ofthese samples to each of six or more laboratories for full-scaletesting was not considered to be practical. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.
This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.
ASTM D4189 – 水のシルト密度指数（SDI）の標準試験法