1、Designation: F316 03 (Reapproved 2011)Standard Test Methods forPore Size Characteristics of Membrane Filters by BubblePoint and Mean Flow Pore Test1This standard is issued under the fixed designation F316; the number immediately following the designation indicates the year of originaladoption or, in
2、 the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscriptepsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 These test methods cover the determination of two ofthe pore size properties of mem
3、brane filters with maximumpore sizes from 0.1 to 15.0 m.1.2 Test Method A presents a test method for measuring themaximum limiting pore diameter of nonfibrous membranes.The limiting diameter is the diameter of a circle having thesame area as the smallest section of a given pore (Fig. 1).1.3 Test Met
4、hod B measures the relative abundance of aspecified pore size in a membrane, defined in terms of thelimiting diameter.1.4 The analyst should be aware that adequate collaborativedata for bias statements as required by Practice D2777 is notprovided. See the precision and bias section for details.1.5 T
5、he values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.6 This standard may involve hazardous materials, opera-tions, and equipment. This standard does not purport toaddress all of the safety concerns, if any, associated with itsuse. I
6、t is the responsibility of the user of this standard toestablish appropriate safety and health practices and deter-mine the applicability of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD1193 Specification for Reagent WaterD2777 Pr
7、actice for Determination of Precision and Bias ofApplicable Test Methods of Committee D19 on WaterE128 Test Method for Maximum Pore Diameter and Per-meability of Rigid Porous Filters for Laboratory Use3. Terminology3.1 DefinitionsFor definitions of other terms used in thesetest methods, refer to Ter
8、minology D1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 pore sizecapillary equivalent pore diameter.3.2.2 limiting pore diameterdiameter of a circle havingthe same area as the smallest section of a given pore.TEST METHOD AMAXIMUM PORE SIZE4. Summary of Test Method4.1 The bubble point
9、 test for maximum pore size is per-formed by prewetting the filter, increasing the pressure of gasupstream of the filter at a predetermined rate and watching forgas bubbles downstream to indicate the passage of gas throughthe maximum diameter filter pores.4.2 The pressure required to blow the first
10、continuousbubbles detectable by their rise through a layer of liquidcovering the filter is called the 9bubble point9, and is used tocalculate maximum pore size.5. Significance and Use5.1 This test method may be used to:5.1.1 Determine the maximum pore size of a filter,5.1.2 Compare the maximum pore
11、sizes of several filters,and5.1.3 Determine the effect of various processes such asfiltration, coating, or autoclaving on the maximum pore size ofa membrane.1These test methods are under the jurisdiction of ASTM Committee D19 onWater and are the direct responsibility of Subcommittee D19.08 on Membra
12、nes andIon Exchange Materials.Current edition approved May 1, 2011. Published June 2011. Originallyapproved in 1970 as F316 70. Last previous edition approved in 2003 asF316 03. DOI: 10.1520/F0316-03R11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Ser
13、vice at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.FIG. 1 Examples of Limiting Diameters1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.2 Me
14、mbrane filters have discrete pores from one side tothe other of the membrane, similar to capillary, tubes. Thebubble point test is based on the principle that a wetting liquidis held in these capillary pores by capillary attraction andsurface tension, and the minimum pressure required to forceliquid
15、 from these pores is a function of pore diameter. Thepressure at which a steady stream of bubbles appears in this testis the bubble point pressure. The bubble point test is significantnot only for indicating maximum pore size, but may alsoindicate a damaged membrane, ineffective seals, or a systemle
16、ak.5.3 The results of this test method should not be used as thesole factor to describe the limiting size for retention ofparticulate contaminants from fluids. The effective pore sizecalculated from this test method is based on the premise ofcapillary pores having circular cross sections, and does n
17、otrefer to actual particle size retention. See Test Method E128 foradditional information.6. Apparatus6.1 Filter Holder, as shown in Fig. 2, consisting of a baseA,a locking ring B, O-ring seal C, support disk D, and gas inletE. The support disk shall be 2-ply construction, consisting of a100 by 100
18、mesh or finer screen and a perforated metal platefor rigidity. The diameter of the test filter may be either 25 or47 mm, as appropriate to the holder being used for the test.6.2 Manifold, as shown in Fig. 3, a micrometric flow controlvalve capable of providing a linear rise in pressure and a gasball
19、ast of at least 16 000-cm3capacity.NOTE 1For less accurate determinations, the simplified apparatusshown in Fig. 4 may be used.6.3 Pressure Gages (and mercury manometer if required),covering the range of pressures needed for the pore sizes underinvestigation (see Table 1).6.4 Metal Punch, used to cu
20、t a suitable size filter from thetest sheet to fit the test filter holder.7. Reagents7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of th
21、e American Chemical Societywhere such specifications are available.3Other grades may beused provided it is first ascertained that the reagent is ofsufficient high purity to permit its use without lessening theaccuracy of the determination.7.2 Water, conforming to Specification D1193, Type IV orhighe
22、r purity.7.3 Denatured Alcohol.7.4 Petroleum Distillate, with surface tension of 30dynes/cm at 25C.7.5 Mineral Oil, such as USP liquid petrolatum heavy, withsurface tension of 34.7 dynes/cm at 25C.7.6 1,1.2-trichloro-l,2,2-trifluoroethane (Freon TFt), avail-able from commercial chemical supply house
23、s.7.7 Clean Gas Pressure Source, with regulation (filtered airor nitrogen).NOTE 2Table 1 lists the nominal surface tension of these liquids at25C. Table 2 lists the simplified maximum pore size formulas based onthese values, where the liquid completely wets the membrane.8. Procedure8.1 Wet the test
24、membrane completely by floating it on apool of the liquid. Use a vacuum chamber to assist in wettingthe filter, if needed.8.2 Place the wet membrane in the filter holder.8.3 Close the filter holder and apply slight gas pressure toeliminate possible liquid back flow.8.4 Cover the perforated metal pla
25、te with 2 to 3 mm of testliquid.8.5 Increase the gas pressure slowly. Record the lowestpressure at which a steady stream of bubbles rises from thecentral area of the liquid reservoir.NOTE 3Faulty sealing may cause erroneous bubbling from the sealingedge of the liquid reservoir. Be sure to record the
26、 bubble point pressurewith bubbles from the central area of the reservoir (see Fig. 5).9. Calculation9.1 If the test liquid is known to wet the membranecompletely, calculate the maximum pore size from the follow-ing equation:d 5 Cg/p (1)where:d = limiting diameter, m,g = surface tension, mN/m, (dyne
27、s/cm),p = pressure, Pa or cm Hg, andC = constant, 2860 when p is in Pa, 2.15 when p is in cmHg, and 0.415 when p is in psi units.NOTE 4The fluid must completely wet the membrane filter with thecontact angle being zero. If the contact angle is greater than zero, thecalculated effective pore size will
28、 be larger than the actual effective poresize rating.3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For Suggestions on the testing of reagents notlisted by the American Chemical Society, see Annual Standards for LaboratoryChemicals, BDH Ltd.,
29、Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.FIG. 2 Filter HolderF316 03 (2011)210. Reporting Results10.1 Record the minimum pressure for gas passage asindicated by continuous bubbles. Record the maximum pores
30、ize calculated, along with identification of the membranetested and the liquid used.TEST METHOD BDETERMINATION OF PORESIZE DISTRIBUTION11. Summary of Test Method11.1 A fluid-wet filter will pass air when the applied airpressure exceeds the capillary attraction of the fluid in thepores. Smaller pores
31、 will exhibit similar behavior at higherpressures. The relationship between pore size and pressure hasbeen established, as indicated in Table 2.11.2 By comparing the gas flow rates of both a wet and dryfilter at the same pressures, the percentage of the flow passingthrough the filter pores larger th
32、an or equal to the specified sizemay be calculated from the pressure-size relationship. Byincreasing pressure in small steps, it is possible to determinethe flow contribution of very small pore size increments bydifference.11.3 To determine the mean flow pore size, a pressure issought at which the w
33、et filter flow is one half of the dry filterflow.12. Significance and Use12.1 This test method may be used to:Key Quantity Component1 1 Filter2 1 Pressure regulator3 1 Pressure gage4 1 Valve shutoff, manual5 1 Valve, flow control, manual6 4 Valve, solenoid, nc7 1 Air ballast8 1 Quick disconnect fitt
34、ing9 2 Open filter holder, 47 mm10 1 Valve, 3-way, manual11 1 Test gage, 0-0.3 kPa (0-30 psig)12 1 Test gage, 0-0.8 kPa (0-100 psig)13 1 Exhaust silencer14 2 Pilot light, red, elec.15 1 Switch, spdt, elec.FIG. 3 Manifold for Bubble Point TestingFIG. 4 Test Setup (Simplified)F316 03 (2011)312.1.1 Det
35、ermine the pore size distribution of a membranefilter,12.1.2 Determine the mean flow pore size of a membranefilter,12.1.3 Determine the effect of processes such as steriliza-tion, upon the pore size distribution,12.1.4 Measure the maximum pore size of a membranefilter, and12.1.5 Determine the gas fl
36、ow rate of a filter, and thereby itsgas flow capability.13. Apparatus13.1 Clean Gas Pressure Source, with regulation (filteredair or nitrogen).13.2 Pressure Gage (or set of gages), covering the neces-sary pressure range for the pore sizes under study. (See Table1.)13.3 Closed Filter Holder, (see Fig
37、. 6).NOTE 5Two l-in. (25-mm) filter holders, instead of one holder,eliminate the task of cleaning the filter holder after a fluid-wet air flowdetermination. A two-position gas valve to switch the gas pressure fromdry to wet holders may be used (see Fig. 7).13.4 Set of Rotameters, covering the range
38、from 0 to 100L/min.13.5 Test Tube and Capillary Tube, to serve for detection ofthe bubble point.13.6 In-Line Fluid Trap, to protect the rotameters from thefluid.13.7 Appropriate Fittings, Hose, Connectors, Piping,toassemble apparatus as shown in Figs. 6 and 7.13.8 x-y Recorder, to assist in graphing
39、 results of mean flowpore test.14. Reagents14.1 Mineral Oil, such as USP liquid petrolatum heavy.15. Procedure for One Holder ( Fig. 6)15.1 Place a dry filter sample disk in the filter holder.15.2 Close the holder and apply gas pressure in increments.TABLE 1 Pressure Ranges RequiredFluid UsedPore Si
40、ze Range to be Investigated (Alternative psi)$1m $0.5 m $0.1 m $0.05 mSurface Tension,dynes/cmat 25CWater 0 to 155 cm Hg(0 to 30 psi)0 to 310 cm Hg(0 to 60 psi)0 to 775 cm Hg(0 to 150 psi)0 to 3100 cm Hg(0 to 600 psi)72.0Petroleum distillate 0 to 65 cm Hg(0 to 15 psi)0 to 130 cm Hg(0 to 25 psi)0 to
41、325 cm Hg(0 to 65 psi)0 to 1300 cm Hg(0 to 250 psi)30.0Denatured alcohol 0 to 50 cm Hg(0 to 10 psi)0 to 100 cm Hg(0 to 20 psi)0 to 250 cm Hg(0 to 50 psi)0 to 1000 cm Hg(0 to 200 psi)22.3Mineral oil 0 to 75 cm Hg(0 to 15 psi)0 to 150 cm Hg(0 to 30 psi)0 to 305 cm Hg(0 to 75 psi)0 to 1500 cm Hg(0 to 3
42、00 psi)34.7Freon TFT 0to40cmHg(0 to 8 psi)0to80cmHg(0 to 16 psi)0 to 200 cm Hg(0 to 40 psi)0 to 800 cm Hg(0 to 100 psi)17.3TABLE 2 Calculation of Maximum Pore Size from Bubble Point Pressure,Ad = Cl/PNOTERefer to Appendix X1 for derivation of maximum pore size formula.Fluid UsedPressure Units of Bub
43、ble Pointcm Hg psi PaWater 155/Bubble Point 30.0/Bubble Point 2.06 3 105/Bubble PointPetroleum distillate 64.6/Bubble Point 12.5/Bubble Point 8.58 3 104/Bubble PointDenatured alcohol 47.75/Bubble Point 9.25/Bubble Point 6.38 3 104/Bubble PointMineral oil 74.5/Bubble Point 14.4/Bubble Point 9.92 3 10
44、4/Bubble PointFreon TFT 37.2/Bubble Point 7.2/Bubble Point 4.95 3 104/Bubble PointAExampleA certain filter was observed to have a bubble point of 41.0 psi with petroleum distillate:Size (m) = 12.5/41.0 psiTherefore, maximum pore size = 0.305 m.FIG. 5 Examples of Erroneous Bubble PointsF316 03 (2011)
45、415.3 Plot gas flow versus gas pressure over the intendedrange of use. (Estimate from pore size-pressure formula, seeTable 1.)15.4 Reduce gas pressure and remove the filter from theholder.15.5 Completely wet the filter in mineral oil, replace the wetfilter in the holder, and apply a slight pressure,
46、 checking to seethat a tight seal exists.15.6 Increase pressure gradually and record the pressure ofthe first gas flow detected by the capillary tube tip immersed inthe test tube half-filled with mineral oil.15.7 Change to rotameters and plot the fluid-wet filter gasflow versus pressure on the same
47、coordinates as for the plotmade in accordance with 15.3.15.8 Reduce the pressure, remove the filter, and clean theholder for the next test.16. Procedure for Two Holders ( Fig. 7)16.1 Place a dry filter in the holder to be used exclusivelyfor dry filters.16.2 Wet a filter of the same type and lot as
48、the filter usedin 16.1, in mineral oil and place it in a holder to be usedexclusively for wet filters.16.3 Apply gas pressure to the dry filter and plot gas flowversus gas pressure.16.4 Change the two position valve to apply gas pressure tothe wet filter holder and record the first gas flow as detec
49、ted bythe capillary tube as the bubble point. Switch to rotameters andplot fluid-wet gas flow versus gas pressure.17. Calculation of Mean Flow Pore Size17.1 Record the minimum pressure for gas passage (bubblepoint pressure). Calculate the maximum pore size from theformula in 9.1 and correlation data in Table 2.17.2 Using the graph from 16.3, draw the line (or curve)corresponding to one half the dry gas-flow rate of the testedfilter. Find the intersection of this (one-half dry-flow) line andthe wet flow line (or curve), as shown in Fig. 8. Determine the
